Alzheimer's & other dementias
In contrast to a number of studies indicating benefits of nonsteroidal anti-inflammatory drugs (NSAIDs) in preventing Alzheimer’s, a large, long-running study following 2,736 members of a healthcare delivery system for 12 years, has revealed that not only did use of these drugs not reduce the risk of developing dementia, the risk among these very elderly (most were over age 83 when they developed dementia) was 66% higher among heavy NSAID users than among people who used little or no NSAIDs. Heavy use was defined as having prescriptions for NSAIDs at least 68% of the time in two years. Although this seems to contradict earlier research, it may be consistent with the theory that NSAID use delays the onset of Alzheimer's – thus, studies of younger NSAID users would show fewer Alzheimer's cases, while groups of older people might show more cases.
Breitner, J.C.S. et al. 2009. Risk of dementia and AD with prior exposure to NSAIDs in an elderly community-based cohort. Neurology, Published online April 22, 2009.
Systemic inflammation – inflammation in the body as a whole – is known to have direct effects on brain function, but there has been little research into the impact of systemic inflammation on the progress of dementia and neurodegenerative diseases. Now, in a study to mimic the effect of bacterial infection in people with dementia, a mouse study has revealed that that the inflammatory response to infection in mice with prior neurodegenerative disease leads to exaggerated symptoms of the infection, causes changes in memory and learning and leads to accelerated progression of dementia.
Cunningham, C. et al. In press. Systemic Inflammation Induces Acute Behavioral and Cognitive Changes and Accelerates Neurodegenerative Disease. Biological Psychiatry.
Previous studies have suggested that nonsteroidal anti-inflammatory drugs are associated with a lower risk of developing Alzheimer’s. A clinical trial involving over 2000 older adults (70+) with a family history of Alzheimer’s disease compared a twice daily treatment of 200 milligrams of either the NSAID celecoxib, or the NSAID naproxen sodium, or a placebo. The trial lasted from March 2001 to December 2004. The study found not only that NSAIDs didn’t improve cognitive function, but that naproxen (but not celecoxib) was associated with significantly lower cognitive performance.
ADAPT Research Group. 2008. Cognitive Function Over Time in the Alzheimer's Disease Anti-inflammatory Prevention Trial (ADAPT): Results of a Randomized, Controlled Trial of Naproxen and Celecoxib. Archives of Neurology, 65(7), (doi:10.1001/archneur.2008.65.7.nct70006).
A very large five-year study of older veterans (55+) has found that those who used ibuprofen for more than five years were more than 40% less likely to develop Alzheimer’s disease. Results also showed that the longer ibuprofen was used, the lower the risk for dementia. Other types of NSAIDs, such as indomethacin, were associated with a 25% reduced risk, however others, such as celecoxib, didn’t show any benefit. There was no obvious connection between those which were associated with reduced risk and those that weren’t. It may be that the effect is a product of some other cause.
Vlad, S.C. et al. 2008. Protective effects of NSAIDs on the development of Alzheimer disease. Neurology, 70, 1672-1677.
And demonstrating that the jury is still out on NSAIDs, a review of six studies has found that people who used NSAIDs had a 23% lower risk of developing Alzheimer’s disease compared to those who never used NSAIDs. The risk reduction did not appear to depend upon the type of NSAID taken. However, the researchers were specifically looking for a difference between those NSAIDs that lower Aβ1-42 amyloid, which was what they didn’t find — and this agrees with the finding of the large veteran study. The findings of this study then may be taken as supporting the view that specific NSAIDs may be of benefit rather than a particular class of them.
Szekely, C.A. et al. 2008. No advantage of Aβ42-lowering NSAIDs for prevention of Alzheimer dementia in six pooled cohort studies. Neurology, 70, 2291-2298.
Evidence that aspirin and other anti-inflammatory drugs may protect against dementia has been inconclusive. Now a large, long-running study involving 6,377 women aged 65 years or more, over ten years, has found that those who took low dose aspirin (100 mg on alternate days) performed at similar levels to a placebo group on cognitive tests. However, there was evidence of benefit in one very specific area of cognition: category fluency.
 Kang, J H., Cook N., Manson JA., Buring J. E., & Grodstein F.
(2007). Low dose aspirin and cognitive function in the women's health study cognitive cohort.
BMJ. 334(7601), 987 - 987.
Full text is available at http://tinyurl.com/25kzxf
It’s long been known that patients regularly taking nonsteroidal anti-inflammatory drugs, such as ibuprofen and naproxen, seem to have less risk of developing Alzheimer's. It’s been suggested that this might mean that Alzheimer's is a product of inflammation in the brain, and that damage happens when the microglia, the brain's immune cells, become overactive and attack healthy neurons. A new study of autopsy brain tissue, and of in vitro rat cultures indicates that, on the contrary, what’s happening is that, as microglia age, they lose their ability to protect the brain. Moreover, the latest study into the effects of anti-inflammatory drugs found no benefit for those suffering from Alzheimer’s. Indeed, it is possible that such drugs might exacerbate the problem. It is speculated that microglia may have the potential to both protect and attack neurons. The key may lie in the way microglia interact with beta-amyloid protein.
Following earlier research showing three commonly used nonsteroidal anti-inflammatory drugs (NSAIDs) were capable of selectively lowering the levels of Abeta42 (an isoform of the amyloid beta protein) in mice, investigation of 20 commonly used NSAIDs found 8 FDA-approved drugs successfully lowered Abeta42 levels in mice at doses achievable in humans.
Eriksen, J.L. et al. 2003. NSAIDs and enantiomers of flurbiprofen target γ-secretase and lower Aß42 in vivo. Journal of Clinical Investigation, 112, 440-449.
A review of 9 observational studies that examined the role of NSAID use in preventing Alzheimer's disease found the pooled relative risk of Alzheimer's disease among users of NSAIDs was 0.72. The risk was 0.95 among short term users (< 1 month), 0.83 among intermediate term (mostly < 24 months) and 0.27 for long term (mostly > 24 months) users. The pooled relative risk in 8 studies of aspirin use was 0.87. It was concluded that NSAIDs offer some protection against the development of Alzheimer's disease.
Etminan, M., Gill, S. & Samii, A. 2003. Effect of non-steroidal anti-inflammatory drugs on risk of Alzheimer's disease: systematic review and meta-analysis of observational studies. BMJ, 327, 128.
Examination of genetically engineered mice and of brain tissue from deceased Alzheimer's patients has found that the buildup of amyloid plaques in the brain dramatically inhibits six genes known to be important for the formation of new memories. The finding suggests a new approach to the treatment of Alzheimer’s disease, combining amyloid-lowering treatment with other strategies designed to block the effect of amyloid on these genes.
Dickey, C.A. et al. 2003. Selectively Reduced Expression of Synaptic Plasticity-Related Genes in Amyloid Precursor Protein + Presenilin-1 Transgenic Mice. Journal of Neuroscience, 23, 5219-5226.
A study of 93 patients with dementia has found that quetiapine, an anti-psychotic drug commonly used in nursing homes to treat agitation and related symptoms in people with Alzheimers' disease, actually worsens patients' illness, significantly speeding up their rate of cognitive decline. Unfortunately, quetiapine had been regarded as one of the safer of the antipsychotic drugs available. There have been safety concerns with the two most commonly used antipsychotic drugs in people with dementia, risperidone and olanzapine, because of increased risk of stroke. Participants in the trial who were taking rivastigmine showed little or no worsening of their illness. Neither drug had any effect on agitation.
Ballard, C. et al. 2005. Quetiapine and rivastigmine and cognitive decline in Alzheimer's disease: Randomised double blind placebo controlled trial. British Medical Journal, 330, 874-7.
Exelon ® (rivastigmine tartrate) is one of the drugs used to treat the symptoms of mild-to-moderate Alzheimer’s. A new study suggests that the effects of Exelon might be more significant than was thought — it may be able to delay progression of the disease. The study found that 26 weeks after discontinuing treatment , those who had been on Exelon showed less cognitive decline than patients who had previously taken a placebo.
Farlow, M., Potkin, S., Koumaras, B., Veach, J. & Mirski, D. 2003. Analysis of Outcome in Retrieved Dropout Patients in a Rivastigmine vs Placebo, 26-Week, Alzheimer Disease Trial. Archives of Neurology, 60, 843-848.
A one-year study found rivastigmine tartrate (Exelon®) reduces the cognitive decline of people with mild to moderate Alzheimer's disease. 545 patients completed the initial six-month phase of the trial and 532 then agreed to extend the trial another six months. Patients who received the higher dose of rivastigmine from the beginning had higher cognitive scores at the end than those patients who received a placebo or the lower dose during the first six months. This suggests early treatment with a high dose may provide benefits that are lost if treatment is delayed.
Farlow, M., Anand, R., Messina Jr, J., Hartman, R., & Veach, J. (2000). A 52-Week Study of the Efficacy of Rivastigmine in Patients with Mild to Moderately Severe Alzheimer’s Disease. European Neurology, 44(4), 236–241. doi:10.1159/000008243
Data from 1.4 million Canadians aged 67 and older has revealed that older patients hospitalized with bradycardia were more than twice as likely to have recently started on a cholinesterase inhibitor such as donepezil for Alzheimer's disease compared to those without bradycardia. Bradycardia is an abnormally slow resting heart rate (under 60 beats per minute). Although it can be asymptomatic, it can also cause fainting, palpitations, shortness of breath, or even death. Although there are three cholinesterase-inhibiting drugs approved for use in Canada, most had been prescribed donepezil. The findings add weight to recent guidelines suggesting that doctors should not prescribe cholinesterase inhibitors for dementia patients as a matter of course, but weigh the potential risks and benefits.
Park-Wyllie, L. Y., Mamdani, M. M., Li, P., Gill, S. S., Laupacis, A., & Juurlink, D. N. (2009). Cholinesterase Inhibitors and Hospitalization for Bradycardia: A Population-Based Study. PLoS Med, 6(9), e1000157. doi: 10.1371/journal.pmed.1000157. Full text available at http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fjournal.pmed.1000157
A three-year study involving 756 people with mild cognitive impairment found increases in depressive symptoms was positively associated with increased risk in developing Alzheimer’s. The study also found that, for those who were depressed, taking the Alzheimer’s drug donepezil significantly reduced the risk of developing Alzheimer’s, compared to those taking vitamin E or placebo. Donepezil had little effect on those who were not depressed.
Lu, P.H. et al. 2009. Donepezil delays progression to AD in MCI subjects with depressive symptoms. Neurology, 72, 2115-2121.
A small sample of adults with mild age-related memory loss was randomly assigned a daily placebo or Aricept. Although both groups scored the same on memory tests, PET brain scans before and after 18 months of treatment showed that those given Aricept had an increased rate of metabolism and looked more normal than the brains of those who took the placebo. It’s suggested that the treatment of early symptoms of memory loss may protect the brain.
The findings were presented July 30 at the International Conference on Alzheimer's Disease 2008.
A six-month study involving 343 people with severe Alzheimer’s disease has found that donepezil, a drug used to treat mild to moderate Alzheimer’s, stabilized or improved cognitive function in 63% of those taking donepezil compared to 39% of those taking placebo. Compared to the placebo group, those taking donepezil showed improvement in memory, language, attention, and recognizing one’s name. The donepezil group also showed less of a decline in social interaction, skills needed to complete a jigsaw puzzle, and arranging sentences compared to the placebo group.
Black, S.E. et al. 2007. Donepezil preserves cognition and global function in patients with severe Alzheimer disease. Neurology, 69, 459-469.
According to a new study, the drug donepezil measurably (but still only slightly) slows the rate of hippocampal shrinkage in patients with mild cognitive impairment (a pre-Alzheimer's condition) who carried the apolipoprotein E4 (APOE 4) gene variant. The study involved 131 patients with mild cognitive impairment. For APOE 4 carriers, the rate of hippocampal atrophy was 4.5% per year, versus 6.14% in placebo-treated patients. Rates of shrinkage for cognitively normal people in their late 70s are approximately 1.4 percent per year. Vitamin E had no significant effect on atrophy for any patients.
Findings were presented July 17 at the Alzheimer's Association International Conference on Alzheimer's Disease and Related Disorders in Madrid, Spain.
An experimental drug – a compound known as SGS742 – has been successful in animal studies in improving memory, and is now in human clinical trials. The drug works by blocking certain chemicals that interfere with memory formation, thus enabling better acquisition and retention of new information. It alters the activity of gene control machinery that is important for memory consolidation. It was most effective when used in conjunction with Aricept, an established Alzheimer’s drug.
Helm, K.A., Haberman, R.P., Dean, S.L., Hoyt, E.C., Melcher, T., Lund, P.K. & Gallagher, M. 2005. GABAB receptor antagonist SGS742 improves spatial memory and reduces protein binding to the cAMP response element (CRE) in the hippocampus. Neuropharmacology, 48(7), 956-64
In a study of people with mild cognitive impairment, those who took the drug donepezil were at reduced risk of progressing to a diagnosis of Alzheimer's during the first years of the trial, but by the end of the 3-year study there was no benefit from the drug. Of the 769 participants, 212 developed possible or probable Alzheimer’s within the 3-year study period; the donepezil group's risk of progression to a diagnosis of Alzheimer’s was reduced by 58% one year into the study, and 36% at 2 years, but no risk reduction at the end of three years. Vitamin E was also tested in the study and was found to have no effect at any point in the study.
Petersen, R.C. et al. 2005. Vitamin E and Donepezil for the Treatment of Mild Cognitive Impairment. New England Journal of Medicine, 352 (23), 2379-2388.
Preliminary data from a recently completed clinical trial of 769 patients with mild cognitive impairment indicates that those taking the drug donepezil were at reduced risk of progressing to Alzheimer's disease for 18 months. The reduced risk disappeared after 18 months, and by the end of the 3-year study, the probability of progressing to Alzheimer’s was the same in the two groups. The study compared donepezil, vitamin E, or placebo. There was no apparent benefit from vitamin E.
The data were presented at the Alzheimer Association's 9th International Conference on Research on AD and Related Disorders (ICAD) in Philadelphia on July 18, 2004.
A study involving 565 Alzheimer’s patients has found that while donepezil did improve tests of mental and functional ability over the first 2 years of treatment, the improvement was slight, and there was no significant delay in institutionalization or progression of disability. There were also no differences between donepezil and placebo in behavioral and psychological symptoms, formal care costs, unpaid caregiver time, adverse events or deaths, or between the two doses of donepezil used in the study.
AD2000 Collaborative Group. 2004. Long-term donepezil treatment in 565 patients with Alzheimer's disease (AD2000): randomised double-blind trial. The Lancet, 363 (9427), 2105-15.
A new analysis from the Moderate to Severe Alzheimer's Disease Study (MSAD), previously published in Neurology in August 2001, suggests that ARICEPT® may also be helpful to those with more advanced Alzheimer’s. The study involved 145 patients with severe Alzheimer's disease who were residing in the community or in assisted living settings. Patients requiring total nursing care were ineligible. ARICEPT®-treated patients showed cognitive improvement ; improved or stable global function; less decline on activities of daily living; fewer behavioral disturbances. Some 10% had to drop out because of adverse reactions.
The data were presented at the American Academy of Neurology (AAN) 55th Annual Meeting.
Results from the first study to directly compare the two Alzheimer drugs, ARICEPT® (donepezil HCl tablets) and Reminyl® (galantamine HBr tablets), found that ARICEPT-treated patients showed significant benefit over patients receiving Reminyl®. Not only were cognitive benefits greater, but ARICEPT® was tolerated significantly better.
The study was presented at the 7th International Geneva/Springfield Symposium on Advances in Alzheimer Therapy (AAT) in Geneva, Switzerland.
The benefits of ARICEPT® (donepezil hydrochloride) may extend into more advanced stages of Alzheimer's disease than previously investigated, according to a first-ever published study of ARICEPT® in patients with moderate to severe Alzheimer's disease, which found significant benefits in patient function, cognition, behavior, and activities of daily living, with very good tolerability. ARICEPT® is approved for the treatment of symptoms of mild to moderate Alzheimer’s disease. Further study of ARICEPT® in patients with severe Alzheimer's disease is currently under way.
Feldman, H., Gauthier, S., Hecker, J., Vellas, B., Subbiah, P., & Whalen, E. (2001). A 24-week, randomized, double-blind study of donepezil in moderate to severe Alzheimer’s disease. Neurology, 57(4), 613–620. doi:10.1212/WNL.57.4.613
In a 54-week U.S. study of 415 people with mild to moderate Alzheimer's, patients who took the drug donepezil maintained their level of functioning in everyday activities such as shopping and fixing meals, 72 percent longer than those who received a placebo did. The study measured the amount of time before patients' functioning declined based on a clinical rating scale. Those taking donepezil declined, on average, five months later than the people taking the placebo.Another study found that patients with mild to moderate Alzheimer's disease taking placebo declined by about twice as much as those taking donepezil, based on a scale of cognitive ability, functioning in daily activities and other factors. The one-year study involved 286 people in Scandinavia and the Netherlands.
Mohs, R. C., Doody, R. S., Morris, J. C., Ieni, J. R., Rogers, S. L., Perdomo, C. A., & Pratt, R. D. (2001). A 1-year, placebo-controlled preservation of function survival study of donepezil in AD patients. Neurology, 57(3), 481–488. doi:10.1212/WNL.57.3.481
Winblad, B., Engedal, K., Soininen, H., Verhey, F., Waldemar, G., Wimo, A., … Subbiah, P. (2001). A 1-year, randomized, placebo-controlled study of donepezil in patients with mild to moderate AD. Neurology, 57(3), 489–495. doi:10.1212/WNL.57.3.489
A new study has demonstrated that the drug Aricept® can "switch on" brain cells thought to be irreparably damaged in Alzheimers sufferers. Previous research suggested Aricept had no such dramatic effects. The new findings may enable more effective use to be made of the drug.
A study of 596 patients from 7 countries found that dementia patients receiving long-term treatment with REMINYL (more than 36 months) may be able to stay at home for longer compared to those receiving treatment for shorter periods of time. Experts believe the long-term clinical efficacy of galantamine may be because as well as enhancing levels of the neurotransmitter acetylcholine, it also (unlike other treatments), has a modulating effect on the brain's nicotinic receptors, which is believed to increase their effectiveness. Nicotinic receptors are thought to play a key role in attention, memory and learning.
Pirttilä, T., van Baelen, B. & Kavanagh, S. 2004. Effect of galantamine on time to residential or nursing home admission. Poster presented at the 17th European Congress of Neuropsychopharmacology, Stockholm, Sweden 2004.
In a new analysis of an earlier study, researchers have discovered that the drugs currently used to alleviate the symptoms of Alzheimer’s not only help confusion and memory loss, but also alleviates or delays symptoms like agitation, depression, and psychosis, and thus have flow-on effects of alleviating the burden on caregivers. For patients not already exhibiting behavioral problems, treatment with galantamine delayed their symptoms for more than three years on average. This is added impetus to treat patients with dementia with cholinesterase inhibitors as early as possible.
Cummings, J.L., Schneider, L., Tariot, P.N., Kershaw, P.R. & Yuan, W. 2004. Reduction of Behavioral Disturbances and Caregiver Distress by Galantamine in Patients With Alzheimer’s Disease. American Journal of Psychiatry, 161, 532-538.
Reminyl (galantamine) may be effective in treating dementia in patients with cerebrovascular disease, such as stroke. Data from a study presented at the XVII World Congress of Neurology show that Reminyl improves memory, orientation and language skills of patients with vascular dementia or a combination of Alzheimer's disease and cerebrovascular disease ("mixed" dementia) for at least 12 months. The results also showed that Reminyl improved or maintained the ability of these individuals to perform normal activities of daily living, such as bathing, dressing and doing housework. However, Reminyl is not yet approved for the treatment of vascular dementia.
Several studies presented at the Tenth Congress of the International Psychogeriatric Association (IPA) assessed the impact of Reminyl treatment on patient functioning by exploring the resulting impact on time required of family caregivers. One study of 435 patients from Europe and Canada, focused on the time caregivers spent supervising their family members or assisting them with activities of daily living, such as dressing and bathing. It was found that the time required to supervise patients who received a placebo increased by approximately two hours per day over the six months, while the time spent supervising individuals who took Reminyl did not increase significantly. In addition, the time that caregivers spent assisting patients on placebo with daily-living activities increased steadily throughout the trial, totalling an average of 23 extra minutes per day by the end of six months. On the other hand, caregivers of patients taking Reminyl reported a decrease in the amount of time spent assisting their charges by an average of 38 minutes per day.A different study focused on caregiver distress and analysed data from a five-month study of 286 U.S. patients. Participating caregivers rated the degree of distress they experienced in response to 10 types of patient symptoms, such as hallucinations, delusions and agitation. The analysis found that after five months, distress significantly increased among those caring for patients who took placebo. In contrast, distress scores were not significantly different at the end of the study than at the beginning for those caring for persons who received Reminyl.
Previous studies have demonstrated the benefits of galantamine (Reminyl™) treatment in terms of efficacy and safety in the short-term. A recent study followed 636 Alzheimer’s patients over two years, and found that patients receiving galantamine throughout the study maintained cognitive benefits, while the placebo comparison group declined. Moreover, the cognitive benefits of galantamine increased over time, relative to the predicted rates of decline in untreated patients.
The study was presented at the American Academy of Neurology's 53rd Annual Meeting in Philadelphia.
Another drug for Alzheimer's sufferers has been approved by the FDA. Reminyl® is of the same nature as the other three medications already available( Cognex®, Aricept®, and Exelon®). These are all cholinesterase inhibitors; they interfere with the action of an enzyme that would otherwise reduce the brain's supply of acetylcholine, a chemical messenger that is essential for thought processes and nerve function.
A review of the use of memantine for patients with moderate or severe Alzheimer's disease has concluded there is no scientific evidence of any benefit to this group, either to patients or caregivers. The review covered 7 studies, involving 1913 patients. The longest study lasted 28 weeks. The main problem was a lack of reliable evidence, and a lack of studies of longer duration, as well as a lack of research with relevant patient groups.
New research shows that the drug memantine, praised as "the first and only representative of a new class of Alzheimer drugs", in fact works similar to other existing compounds, and although the data do confirm that memantine shows promising aspects for the treatment of Alzheimer’s, this is only in a narrow concentration range. Its complex pharmacological profile requires careful considerations concerning suitable doses and suitable patient groups.
Drever, B.D. et al. 2007. Memantine acts as a cholinergic stimulant in the mouse hippocampus. Journal of Alzheimer's Disease, 12 (4), 319-333.
A review of nine published studies comprising 2,339 participants has concluded that memantine has a small but significant cognitive benefit for moderate-to-severe Alzheimer’s patients. It also seems to prevent the onset of agitation. Although there was some indication of benefit for those with mild to moderate Alzheimer’s, the effects were not significant. Researchers caution that the drug treats the symptoms only, slowing the progress of the disease only.
Sastre, A. Areosa et al. 2005. Memantine for dementia. The Cochrane Database of Systematic Reviews, Issue 2.
The FDA recently approved memantine for treatment of moderate to severe Alzheimer’s. The drug has been used for some 20 years in Germany. While memantine significantly improved performance in Alzheimer’s sufferers in studies, the effect, as with all Alzheimer’s drugs currently in use, is small.
Tariot, P.N., Farlow, M.R., Grossberg, G.T., Graham, S.M., McDonald, S. & Gergel, I. 2004. Memantine treatment in patients with moderate to severe Alzheimer disease already receiving donepezil: A randomized controlled trial. JAMA, 291, 317-24.
Four drugs — donepezil, galantamine, rivastigmine, and tacrine — are approved for treatment of mild-to-moderate Alzheimer's disease in the U.S., but there are no approved treatments for severe AD. Now an industry-sponsored study has examined memantine for this use. The study involved 252 patients with moderate-to-severe AD, over a period of 28 weeks. Patients were evaluated on 7 tests of cognition, functional capacity, and behavior. Outcomes were significantly better with memantine than with placebo on 4 of these scales, and no significant adverse events were noted. It is not clear yet how clinically meaningful these small improvements are. Memantine has been approved for use in Europe.
Reisberg, B., Doody, R., Stöffler, A., Schmitt, F., Ferris, S. & Möbius, H.J. 2003. Memantine in moderate-to-severe Alzheimer's disease. New England Journal of Medicine, 348, 1333-41.
Data from the Medical Research Council's Cognitive Function and Ageing Study, including post-mortem study of the brains of 456 participants, has enabled researchers to estimate the contribution of each type of pathology to dementia in the population as a whole. The main pathological contributors to dementia were age (18%), small brain (12%), amyloid plaques (8%) and neurofibrillary tangles (11%), small blood vessel disease (12%), multiple vascular pathologies (9%), and hippocampal atrophy (10%). Other significant factors include cerebral amyloid angiopathy (7%) and Lewy bodies (3%). The findings support to the need for a range of strategies, and combination therapies, tailored to the particular needs of the patient. It also points to why particular therapies may be more successful with some individuals but not others.
Matthews, F. E., Brayne, C., Lowe, J., McKeith, I., Wharton, S. B., & Ince, P. (2009). Epidemiological Pathology of Dementia: Attributable-Risks at Death in the Medical Research Council Cognitive Function and Ageing Study. PLoS Med, 6(11), e1000180. doi: 10.1371/journal.pmed.1000180. Full text available at http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fjournal.pmed.1000180
A report just out from the U.K. Department of Health has concluded that as many as 144,000 dementia patients are being given anti-psychotic drugs unnecessarily, and that excessive use of the medication causes an estimated 1,800 deaths and almost as many strokes every year. It recommended that the use of the drugs could be cut by two-thirds over the course of the next three years, but urged carers and family not to act hastily, warning that stopping prescriptions immediately for many patients could be dangerous.
A very large study has found that use of cholinesterase inhibitors (the Alzheimer’s drugs Aricept, Exelon and Reminyl) is associated with increased rates of fainting, slowed heartrate, pacemaker insertion, and hip fracture. Both the injuries incurred from falling and the risks from pacemaker implants are "downstream consequences" of not recognizing that fainting and slowed heartrate may be a consequence of taking these drugs.
Gill, S.S. et al. 2009. Syncope and Its Consequences in Patients With Dementia Receiving Cholinesterase Inhibitors: A Population-Based Cohort Study. Archives of Internal Medicine, 169 (9), 867-873.
The first long-term study of the real-world use of Alzheimer's drugs has found that extended treatment with Alzheimer's disease drugs can significantly slow the rate at which the disorder advances, and combination therapy with two different classes of drugs (cholinesterase inhibitors and memantine) is even better at helping patients maintain their ability to perform daily activities. The results showed significant differences in the rate of symptom progression among all three groups – with the smallest level of decline in those receiving combination therapy. Cholinesterase inhibitors are approved for use in mild to moderate dementia, while memantine has been approved for advanced dementia. But these findings suggest there may be an advantage in prescribing both types of drugs as initial treatment.
Atri, A. et al. 2008. Long-term Course and Effectiveness of Combination Therapy in Alzheimer Disease. Alzheimer Disease & Associated Disorders, 22(3), 209-221.
A review of six clinical trials that had addressed the use of cholinesterase inhibitors (donepezil, rivastigmine and galantamine) with MCI patients has found that in none of the trials did the use of the drugs significantly reduce the rate of progression from MCI to dementia.
Raschetti, R., Albanese, E., Vanacore, N. & Maggini, M. 2007. Cholinesterase inhibitors in mild cognitive impairment: A systematic review of randomised trials. PLoS Medicine, 4(11), e338. Full text available at http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.0040338
A review of the 22 published, double-blind, randomised trials of the three cholinesterase inhibitors currently recommended for Alzheimer’s disease (donepezil, rivastigmine, and galantamine) has found considerable flaws in the methodology of all trials, and concluded that “Because of flawed methods and small clinical benefits, the scientific basis for recommendations of cholinesterase inhibitors for the treatment of Alzheimer's disease is questionable.”
Kaduszkiewicz, H., Zimmermann, T., Beck-Bornholdt, H-P. & van den Bussche, H. 2005. Cholinesterase inhibitors for patients with Alzheimer's disease: systematic review of randomised clinical trials. British Medical Journal, 331, 321-327.
Current Alzheimer’s drugs focus on preventing the breakdown of acetylcholine. Acetylcholine-producing cells are among the first to die in Alzheimer's patients. Research has also shown that the brains of Alzheimer's patients are characterized by excessive immune activation and inflammation, which are induced by overproduction of an inflammation-producing protein called interleukin-1 and related compounds. Now a new study has found that current Alzheimer's drugs cause a marked reduction in the production of interleukin-1. The findings suggest a new interpretation of why acetylcholine is important; when the acetylcholine increases (as a result of the drug), there is a reduction of the production of interleukin-1. The study also describes the use of a new drug (EN101) which produces these effects in a more efficient way than known heretofore by destroying the molecular antecedent (messenger RNA) of the enzyme, rather than simply blocking the enzyme's activity.
Pollak, Y., Gilboa, A., Ben-Menachem, O., Ben-Hur, T., Soreq, H. & Yirmiya, R. 2005. Acetylcholinesterase inhibitors reduce brain and blood interleukin-1 g production. Annals of Neurology, 57(5), 741-745.
New research clarifies how cholinesterase inhibitors alleviate mild-to-moderate Alzheimer's. When scientists chemically blocked receptors for an important neurotransmitter called acetylcholine, even healthy young people found it significantly harder to learn and remember – especially in the face of interference. Cholinesterase inhibitors slow the breakdown of acetylcholine. The finding also helps explain why Parkinson's disease, dementia due to multiple strokes, multiple sclerosis and schizophrenia, are all also associated with memory problems — all these conditions, like Alzheimer’s, are associated with lower levels of acetylcholine in the brain.
Atri, A., Norman, K.A., Nicolas, M.M., Cramer, S.C., Hasselmo, M.E., Sherman, S., Kirchhoff, B.A., Greicius, M.D., Breiter, H.C. & Stern, C.E. 2004. Central Cholinergic Receptors Impairs New Learning and Increases Proactive Interference in a Word Paired-Associate Memory Task. Behavioral Neuroscience, 118 (1).
We know that the E4 variant of the APOE gene greatly increases the risk of developing Alzheimer’s disease, but the reason is a little more mysterious. It has been thought that it makes it easier for amyloid plaques to form because it produces a protein that binds to amyloid beta.
I’ve talked before about the evidence linking diabetes to an increased risk of Alzheimer’s disease, but now a new study suggests that elevated blood sugar levels increase Alzheimer’s risk even in those without diabetes, even in those without ‘pre-diabetes’.
A study involving nearly 6,000 African American older adults has found those with a specific gene variant have almost double the risk of developing late-onset Alzheimer’s disease compared with African Americans who lack the variant. The size of the effect is comparable to that of the ‘Alzheimer’s gene’, APOE-e4.
A study using genetically engineered mice has reversed the rats' memory loss by silencing a gene that helps produce amyloid plaques. The size and number of plaques were reduced by two-thirds within a month.
Singer, O. et al. 2005. Targeting BACE1 with siRNAs ameliorates Alzheimer disease neuropathology in a transgenic model. Nature Neuroscience, 8, 1343-1349.
The first human clinical trial of gene therapy for Alzheimer’s, involving 8 volunteers, has found an increase in the brain’s use of glucose — a sign of brain activity — and a significant slowing of the patients’ rate of cognitive decline in the 6 patients who completed the procedure safely.
Tuszynski, M.H. et al. 2005. A phase 1 clinical trial of nerve growth factor gene therapy for Alzheimer disease. Nature Medicine, 11(5), 551-555.
A new technique using gene therapy to deliver nerve growth factor into regions of the brain where neurons are degenerating is being trialed in a two-year study. The technique, which requires neurosurgery to inject the drug precisely where it is required (the basal forebrain), uses a new drug called CERE-110. Extensive studies in several animal models, including primates, have showed that NGF gene delivery to the basal forebrain prevented the death of cholinergic neurons (which undergo severe degeneration and death in Alzheimer's disease patients).
A small, preliminary study has had some success in delaying brain cell loss in early Alzheimer’s patients through the surgical placement of genetically modified tissue directly into their brains.
The study was reported on April 27 at the American Academy of Neurology meeting in San Francisco.
In a groundbreaking procedure, physicians at the University of California, San Diego (UCSD) School of Medicine have surgically implanted genetically modified tissue into the brain of an Alzheimer's patient. This launches the first phase of an experimental gene therapy protocol for Alzheimer's disease. The therapy delivers a natural molecule called nerve growth factor (NGF) to the dying cells in the brain.If the protocol is successful, implanted cells could begin to affect brain function in a month or two, but Tuszynski cautions that "it may take several years to test the procedure in a large enough number of patients to determine whether it will be useful therapy." The therapy is not expected to cure Alzheimer's disease, but it may restore some brain cells and alleviate symptoms such as short-term memory loss for several years.
Conner, J. M., Darracq, M. A., Roberts, J., & Tuszynski, M. H. (2001). Nontropic actions of neurotrophins: Subcortical nerve growth factor gene delivery reverses age-related degeneration of primate cortical cholinergic innervation. Proceedings of the National Academy of Sciences, 98(4), 1941–1946. doi:10.1073/pnas.98.4.1941
The ever-slowing capacity to clear the build-up of such toxins as isoprostanes and misfolded proteins that accumulate in the brains of Alzheimer's disease patients causes the death of cells involved in memory and language. A preliminary study has shown that reducing the levels of isoprostanes by draining cerebral spinal fluid can stave off future reductions in cognitive abilities. Cognitive scores in the 8 patients receiving the treatment were stable after one year, while scores in those not receiving the treatment declined 20%. The next phase of the study involves nearly 100 patients.
Praticò, D., Yao, Y., Rokach, J., Mayo, M., Silverberg, G.G. & McGuire, D. 2004. Reduction of brain lipid peroxidation by CSF drainage in Alzheimer’s disease patients. Journal of Alzheimer's Disease, 6(4), 385-389.
A pilot study has tested the hypothesis that improving cerebrospinal fluid (CSF) turnover will slow or stop the progression of dementia in people with Alzheimer's disease. CSF shunting for dementia, described in 1969, was largely abandoned due to mixed clinical results and an unacceptably high incidence of adverse events. However recent clinical studies in which CSF shunting was used to treat patients with symptomatic hydrocephalus demonstrated a coincidental lack of cognitive decline in patients who also had Alzheimer's dementia. A pilot study has found Alzheimer's patients who were shunted experienced relative stability while the control group demonstrated a fairly robust decline in cognitive function over the 12 months of the study. A larger, multi-center, controlled clinical trial is now underway.
Silverberg, G.D., Levinthal, E., Sullivan, E.V., Bloch, D.A., Chang, S.D., Leverenz, J., Flitman, S., Winn, R., Marciano, F., Saul, T., Huhn, S., Mayo, M. & McGuire, D. 2002. Assessment of low-flow CSF drainage as a treatment for AD: Results of a randomized pilot study. Neurology, 59, 1139-1145.
An 18-month, double-blind placebo study into a new surgical treatment for Alzheimer’s disease using a device called the COGNIShunt, is being undertaken by neurologists at Emory University. The shunt is designed to drain cerebrospinal fluid (CSF) from the skull and into the abdominal cavity. By reducing the build-up of CSF around the brain, doctors hope this device will help to stabilize the disease. In a pilot study of the COGNIShunt, the device was well tolerated by individuals with mild to moderate Alzheimer’s disease.
Studies of adult neurogenesis in genetically engineered mice have revealed two main reasons why amyloid-beta peptides and apolipoprotein E4 impair neurogenesis, and identified drug treatments that can fix it. The findings point to a deficit in GABAergic neurotransmission or an imbalance between GABAergic and glutamatergic neurotransmission as an important contributor to impaired neurogenesis in Alzheimer’s. While stem cell therapy for Alzheimer’s is still a long way off, these findings are a big step toward that goal.
Gang Li et al. 2009. GABAergic Interneuron Dysfunction Impairs Hippocampal Neurogenesis in Adult Apolipoprotein E4 Knockin Mice. Cell Stem Cell, 5 (6), 634-645. Binggui Sun et al. 2009. Imbalance between GABAergic and Glutamatergic Transmission Impairs Adult Neurogenesis in an Animal Model of Alzheimer's Disease. Cell Stem Cell, 5 (6), 624-633.
Genetically engineered mice performed markedly better on memory tests a month after neural stem cells were injected into their Alzheimer-like brains. The stem cells secreted a protein that created more neural connections, improving cognitive function. Surprisingly, only 6% of the stem cells became neurons (most became ‘support cells’: astrocytes and oligodendrocytes). The benefit of stem cells seemed rather to lie in their secretion of BDNF, which encouraged the formation of new synapses. The direct injection of BDNF also had cognitive benefit, but not as much as with the neural stem cells, which provided a more long-term and consistent supply of the protein.
Norton, M.C. et al. 2009. Caregiver–Recipient Closeness and Symptom Progression in Alzheimer Disease. The Cache County Dementia Progression Study. The Journals of Gerontology Series B: Psychological Sciences and Social Sciences, Advance Access published on June 29, 2009. Full text available at http://www.pnas.org/content/106/32/13594.abstract
In a series of cell culture and animal studies, involving genetically engineered mice, rats, and rhesus monkeys, injections of brain-derived neurotrophic factor (BDNF) resulted in significant improvement in brain functioning and on learning and memory tests. The growth factor, important for neurogenesis, is normally produced in the entorhinal cortex, an area damaged early in Alzheimer’s disease.
Nagahara, A.H. et al. 2009. Neuroprotective effects of brain-derived neurotrophic factor in rodent and primate models of Alzheimer's disease. Nature Medicine, 15, 331–337.
A new way of destroying amyloid-beta proteins has been found. Following previous research showing that the enzyme cathepsin B destroys the protein, scientists have now succeeded in increasing the activity of the enzyme by reducing the activity of the protease inhibitors cystatin C, the enzyme’s natural inhibitor. In mice, this had the effect of improving memory and extending life.
Sun, B. et al. 2008. Cystatin C-Cathepsin B Axis Regulates Amyloid Beta Levels and Associated Neuronal Deficits in an Animal Model of Alzheimer's Disease. Neuron, 60 (2), 247-257.
In a series of studies in transgenic mice, a synthetic peptide designed to block the interaction between apolipoprotein E and amyloid-beta protein reduced the aggregation of toxic amyloid protein in the brain by around 50%. The treated mice showed no memory decline.
Sadowski, M.J. et al. 2006. Blocking the apolipoprotein E/amyloid- interaction as a potential therapeutic approach for Alzheimer's disease. Proceedings of the National Academy of Sciences, 103, 18787-18792. The full text is available at http://www.pnas.org/cgi/content/full/103/49/18787
Recent studies have suggested a link between testosterone loss in men and Alzheimer’s. A new study has now found a correlation between low testosterone and elevated beta-amyloid, providing more support that testosterone depletion in aging men increases the risk of Alzheimer’s. Testosterone belongs to a group of steroid hormones called androgens. The mouse study found that androgen therapy was successful in preventing beta-amyloid accumulation and cognitive decline in castrated mice.
Rosario, E.R. et al. 2006. Androgens Regulate the Development of Neuropathology in a Triple Transgenic Mouse Model of Alzheimer's Disease. Journal of Neuroscience, 26, 13384-13389.
Following previous research suggesting Alzheimer's might be a brain-specific neuroendocrine disorder, or a Type 3 diabetes, a new study has found that stimulation of a receptor in the brain that controls insulin responses prevents several components of neurodegeneration and preserves learning and memory in rats with induced Alzheimer's disease, raising the possibility that patients in the very early stages of Alzheimer’s might be treatable.
de la Monte, S.M. et al. 2006. Therapeutic rescue of neurodegeneration in experimental type 3 diabetes: relevance to Alzheimer’s disease. Journal of Alzheimer's Disease, 10 (1), 89-109.
In a new approach to treating Alzheimer’s, increasing brain levels of ubiquitin C-terminal hydrolase L1 (Uch-L1) — an enzyme that helps neurons rid themselves of excess or aberrant proteins — has restored a great deal of brain activity to mice with Alzheimer's symptoms. The enzyme Uch-L1 is part of a network that controls a memory molecule called CREB, which is inhibited by amyloid beta proteins in people with Alzheimer's. Uch-L1 is found at reduced levels in the Alzheimer's brain. As well as improving memory in genetically engineered mice, treatments that restored Uch-L1 levels corrected deficits in nerve transmission both in brain slices treated with amyloid-beta and in slices taken from transgenic mice.
Gong, B. et al. 2006. Ubiquitin Hydrolase Uch-L1 Rescues B-Amyloid-Induced Decreases in Synaptic Function and Contextual Memory. Cell, 126, 775–788.
Experiments with roundworms have revealed two important proteins that help slow down the accumulation of amyloid-beta. HSF-1 breaks apart amyloid and disposes of it — but aging slows HSF-1, so it can't keep up. DAF-16 helps it out, by clumping extra amyloid together in a way that makes it less toxic. The finding supports recent research indicating amyloid clumps, or plaques, are not the main problem, rather, smaller amyloid tendrils inside cells are. The study also explains why aging increases the likelihood of Alzheimer’s. Most importantly of all, it suggests a new approach to treating Alzheimer’s.
Cohen, E. et al. 2006. Opposing Activities Protect Against Age-Onset Proteotoxicity. Science, 313 (5793), 1604–1610.
A study has identified several new compounds that could play a role in preventing or treating Alzheimer's disease and other degenerative conditions of the nervous system. In culture, these compounds bind with a receptor called p75NTR; a receptor that in the body binds neurotrophins. There is some evidence that in Alzheimer's, some of the neurons that die express the p75NTR binding site, indicating they may be dying because neurotrophins are binding to them. Because the new compounds bind with p75NTR in place of neurotrophins, they may provide a means of preventing damage that neurotrophins would otherwise be causing. The compounds were also found to inhibit the death of oligodendrocytes.
Massa, S.M. et al. 2006. Small, Nonpeptide p75NTR Ligands Induce Survival Signaling and Inhibit proNGF-Induced Death. Journal of Neuroscience, 26, 5288-5300.
Mice were genetically engineered to develop dementia; the transgene was designed to be able to be turned off. The researchers expected that when the transgene expressing the dementia was turned off, memory loss would stop. Instead, they were surprised to find the loss was reversed; the mice regained their memory. A further surprise occurred when it was found that the neurofibrillary tangles, thought to be one of the causes of dementia, remained, and even increased, suggesting that the tangles are not a cause of dementia.
SantaCruz, K. et al. 2005. Tau Suppression in a Neurodegenerative Mouse Model Improves Memory Function, Science, 309 (5733), 476-481.
It has been known that the inflammatory protein ApoE can speed the buildup in the brain of amyloid plaques,but the mechanism has not been known. A mouse study found ApoE is responsible for converting harmless amyloid-beta into the toxic fibrous deposits known as filamentous amyloid. This process is needed to damage nerve cells in parts of the brain controlling memory and cognition. Mice with Alzheimer's disease showed memory deficits only when the ApoE gene was present. The study suggests that preventing ApoE from acting upon amyloid-beta may prove to be an effective means of therapeutic intervention.
Costa, D.A., Nilsson, L.N.G., Bales, K.R., Paul, S.M. & Potter, H. 2004. Apolipoprotein E is required for the formation of filamentous amyloid but not for amorphous AB deposition, in an Aâ PP/PS double transgenic mouse model of Alzheimer's disease. Journal of Alzheimer's Disease, 6, 509–514.
Nilsson, L.N.G., Arendash, G.W., Leighty, R.E., Costa, D.A., Garcia, M.F., Cracciola, J.R., Rojiani, A., Wu, X., Bales, K.R., Paul, S.M. & Potter, H. 2004. Cognitive impairment in PDAPP mice depends on ApoE and ACT-catalyzed amyloid. Neurobiology of Aging, 25 (9), 1153-1167.
Researchers have identified a protein in the brain, "transthyretin," that halts the progression of Alzheimer's disease in human brain tissue by blocking beta-amyloid.
The findings were presented on October 26 at the 34th annual meeting of the Society for Neuroscience in San Diego, Calif.
A study using genetically engineered mice has provided evidence that early clinical treatment of brain lesions (by injecting anti-beta-amyloid antibodies into the hippocampus) can halt the progression of Alzheimer's disease. The clearance of amyloid plaques led to the clearance of the lesions caused by neurofibrillary tangles. The effect on neurofibrillary tangles only occurs, however, if done at a particular stage of the tangle’s growth — the earlier the treatment begins, therefore, the better the chance of success. The demonstration that early treatment of amyloid plaques stops the progression of Alzheimer’s provides support for the controversial theory that the accumulation of amyloid plaques is the initiating trigger of the disease process.
Oddo, S., Billings, L., Kesslak, P., Cribbs, D.H. & LaFerla, F.M. 2004. Aβ Immunotherapy Leads to Clearance of Early, but Not Late, Hyperphosphorylated Tau Aggregates via the Proteasome. Neuron, 43, 321-332.
Researchers have discovered the molecules that play a critical role in making the brain think it is under attack from the amyloid plaques characteristic of Alzheimer’s disease. Microglial cells detect beta amyloid plaques and gear up to fight them as foreign invaders. However, for some unknown reason, they don’t follow through on the attack, but remain inflamed. It is this inflammation that causes a lot of the problem. Research has now shown that the microglial cells at least four different receptor proteins to bind to the amyloid. Each one of these receptor proteins act together at the same time to drive the inflammation. This discovery suggests a new approach to treating Alzheimer’s — finding a means to block these receptors.
Bamberger, M.E., Harris, M.E., McDonald, D.R., Husemann, J. & Landreth, G.E. 2003. A Cell Surface Receptor Complex for Fibrillar b-Amyloid Mediates Microglial Activation. Journal of Neuroscience, 23, 2665-2674.
An animal study has found that a molecule that naturally degrades of the protein beta-amyloid (the substance in the amyloid plaques indicative of Alzheimer’s) appears to reduce the levels of that protein by nearly 50% when delivered by gene therapy.
Marr, R.A., Rockenstein, E., Mukherjee, A., Kindy, M.S., Hersh, L.B., Gage, F.H., Verma, I.M. & Masliah, E. 2003. Neprilysin Gene Transfer Reduces Human Amyloid Pathology in Transgenic Mice. Journal of Neuroscience, 23, 1992-1996.
In a series of studies, a growth factor (BDNF) was introduced into the adult rat brain, and was found to produce new neurons in various brain regions. BDNF is reduced in parts of the brain of those with Huntington’s disease and Alzheimer’s disease. These studies indicate that supplementing the adult brain with BDNF not only supports neurons in those brains, but also induces new neurons from precursor cells.
Pencea, V., Bingaman, K. D., Wiegand, S. J., & Luskin, M. B. (2001). Infusion of Brain-Derived Neurotrophic Factor into the Lateral Ventricle of the Adult Rat Leads to New Neurons in the Parenchyma of the Striatum, Septum, Thalamus, and Hypothalamus. The Journal of Neuroscience, 21(17), 6706–6717. Retrieved from http://www.jneurosci.org/content/21/17/6706
Benraiss, A., Chmielnicki, E., Lerner, K., Roh, D., & Goldman, S. A. (2001). Adenoviral Brain-Derived Neurotrophic Factor Induces Both Neostriatal and Olfactory Neuronal Recruitment from Endogenous Progenitor Cells in the Adult Forebrain. The Journal of Neuroscience, 21(17), 6718–6731. Retrieved from http://www.jneurosci.org/content/21/17/6718
Laboratory-grown human neural stem cells, the building blocks of the brain, were successfully transplanted for the first time into the brains of aged rats and dramatically improved the animals' cognitive function. The results of the study could lay the foundation for new treatments in diseases such as Alzheimer's and Parkinson's.Neural cell transplant studies recently suffered a setback when transplanted fetal cells worsened symptoms in Parkinson's patients. However, such fetal cells are already differentiated. Laboratory-grown stem cells are not differentiated, allowing the host brain to take over, dictating where the stem cells should migrate and what types of cells they should become. As a result, the transplanted cells became functionally integrated into the neuronal circuitry of the host animal. Postmortem examination of the rats' brains demonstrated that the transplanted human brain cells had not only differentiated and were thriving in the new environment, but that the rats' own neuronal fibers had grown dramatically in areas associated with spatial memory.
Qu,T, Brannen, C.L., Kim, H.M., & Sugay, K. (n.d.). Human neural stem cells improve cognitive function of aged brain. Retrieved 27 April 2013, from http://journals.lww.com/neuroreport/Fulltext/2001/05080/Human_neural_ste...
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