risk factors

Hearing loss and dementia linked

March, 2011

Another study builds on earlier indications that hearing loss is a risk factor for dementia, and emphasizes the need for early intervention.

Data from the Baltimore Longitudinal Study on Aging, begun in 1958, has revealed that seniors with hearing loss are significantly more likely to develop dementia than those who retain their hearing. The study involved 639 people whose hearing and cognitive abilities were tested between 1990 and 1994, then re-tested every one to two years. By 2008, 58 (9%) of them had developed dementia (37 of which were Alzheimer’s).

Those with hearing loss at the beginning of the study were significantly more likely to have developed dementia. The degree of hearing loss also correlated with greater risk: those with mild, moderate, and severe hearing loss had twofold, threefold, and fivefold, respectively, the risk of developing dementia over time. The association was maintained after other risk factors, (high blood pressure, smoking, education, age, sex, race) were taken into account.

The reason for the association is not yet known. It’s possible that a common pathology may underlie both, or that the strain of decoding sounds over the years may make the brain more vulnerable to dementia, or that hearing loss makes people more socially isolated (a known risk factor for dementia).

The findings do suggest that hearing loss should be regarded more seriously, and not simply accepted as a natural part of growing old.

Reference: 

Source: 

Topics: 

tags development: 

tags problems: 

Metabolic syndrome linked to memory loss in older people

March, 2011

Three more studies point to the increased risk of memory loss in older adults with cardiovascular problems.

The new label of ‘metabolic syndrome’ applies to those having three or more of the following risk factors: high blood pressure, excess belly fat, higher than normal triglycerides, high blood sugar and low high-density lipoprotein (HDL) cholesterol (the "good" cholesterol). Metabolic syndrome has been linked to increased risk of heart attack.

A new French study, involving over 7,000 older adults (65+) has found that those with metabolic syndrome were 20% more likely to show cognitive decline on a memory test (MMSE) over a two or four year interval. They were also 13% more likely to show cognitive decline on a visual working memory test. Specifically, higher triglycerides and low HDL cholesterol were linked to poorer memory scores; diabetes (but not higher fasting blood sugar) was linked to poorer visual working memory and word fluency scores.

The findings point to the importance of managing the symptoms of metabolic syndrome.

High cholesterol and blood pressure in middle age tied to early memory problems

Another study, involving some 4800 middle-aged adults (average age 55), has found that those with higher cardiovascular risk were more likely to have lower cognitive function and a faster rate of cognitive decline over a 10-year period. A 10% higher cardiovascular risk was associated not only with increased rate of overall mental decline, but also poorer cognitive test scores in all areas except reasoning for men and fluency for women.

The cardiovascular risk score is based on age, sex, HDL cholesterol, total cholesterol, systolic blood pressure and whether participants smoked or had diabetes.

Memory problems may be sign of stroke risk

A very large study (part of the REGARDS study) tested people age 45 and older (average age 67) who had never had a stroke. Some 14,842 people took a verbal fluency test, and 17,851 people took a word recall memory test. In the next 4.5 years, 123 participants who had taken the verbal fluency test and 129 participants who had taken the memory test experienced a stroke.

Those who had scored in the bottom 20% for verbal fluency were 3.6 times more likely to develop a stroke than those who scored in the top 20%. For the memory test, those who scored in the bottom 20% were 3.5 times more likely to have a stroke than those in the top quintile.

The effect was greatest at the younger ages. At age 50, those who scored in the bottom quintile of the memory test were 9.4 times more likely to later have a stroke than those in the top quintile.

 

Together, these studies, which are consistent with many previous studies, confirm that cardiovascular problems and diabetes add to the risk of greater cognitive decline (and possible dementia) in old age. And point to the importance of treating these problems as soon as they appear.

Reference: 

[2147] Raffaitin, C., Féart C., Le Goff M., Amieva H., Helmer C., Akbaraly T. N., et al.
(2011).  Metabolic syndrome and cognitive decline in French elders.
Neurology. 76(6), 518 - 525.

The findings of the second and third studies are to be presented at the American Academy of Neurology's 63rd Annual Meeting in Honolulu April 9 to April 16, 2011

Source: 

Topics: 

tags: 

tags development: 

tags lifestyle: 

tags problems: 

Migraines and headaches linked to more brain lesions in older adults

March, 2011
  • Older adults who have a history of severe headaches are more likely to have a greater number of brain lesions, but do not show greater cognitive impairment (within the study time-frame).

Lesions of the brain microvessels include white-matter hyperintensities and the much less common silent infarcts leading to loss of white-matter tissue. White-matter hyperintensities are common in the elderly, and are generally regarded as ‘normal’ (although a recent study suggested we should be less blasé about them — that ‘normal’ age-related cognitive decline reflects the presence of these small lesions). However, the degree of white-matter lesions is related to the severity of decline (including increasing the risk of Alzheimer’s), and those with hypertension or diabetes are more likely to have a high number of them.

A new study has investigated the theory that migraines might also lead to a higher number of white-matter hyperintensities. The ten-year French population study involved 780 older adults (65+; mean age 69). A fifth of the participants (21%) reported a history of severe headaches, of which 71% had migraines.

Those with severe headaches were twice as likely to have a high quantity of white-matter hyperintensities as those without headaches. However, there was no difference in cognitive performance between the groups. Those who suffered from migraines with aura (2% of the total), also showed an increased number of silent cerebral infarcts — a finding consistent with other research showing that people suffering from migraine with aura have an increased risk of cerebral infarction (or strokes). But again, no cognitive decline was observed.

The researchers make much of their failure to find cognitive impairment, but I would note that, nevertheless, the increased number of brain lesions does suggest that, further down the track, there is likely to be an effect on cognitive performance. Still, headache sufferers can take comfort in the findings, which indicate the effect is not so great that it shows up in this decade-long study.

Reference: 

Source: 

Topics: 

tags: 

tags development: 

tags problems: 

Steep cholesterol decline in older women linked to Alzheimer's risk

February, 2011

A long-running study has found cholesterol levels at in mid-life were not linked to later dementia in women, but marked decline in cholesterol level over the study period was.

Research into the link, if any, between cholesterol and dementia, has been somewhat contradictory. A very long-running Swedish study may explain why. The study, involving 1,462 women aged 38-60 in 1968, has found that cholesterol measured in middle or old age showed no link to dementia, but there was a connection between dementia and the rate of decline in cholesterol level. Those women whose cholesterol levels decreased the most from middle to older age were more than twice as likely to develop dementia as those whose cholesterol levels increased or stayed the same (17.5% compared to 8.9%).After 32 years, 161 women had developed dementia.

Later in life, women with slightly higher body mass index, higher levels of cholesterol and higher blood pressure tend to be healthier overall than those whose weight, cholesterol and blood pressure are too low. But it is unclear whether "too low" cholesterol, BMI and blood pressure are risk factors for dementia or simply signs that dementia is developing, for reasons we do not yet understand.

On the other hand, a recent rat study has found that consuming a high cholesterol diet for five months caused memory impairment, cholinergic dysfunction, inflammation, enhanced cortical beta-amyloid and tau and induced microbleedings — all of which is strikingly similar to Alzheimer's pathology. And this finding is consistent with a number of other studies. So it does seem clear that the story of how exactly cholesterol impacts Alzheimer’s is a complex one that we are just beginning to unravel.

In light of other research indicating that the response of men and women to various substances (eg caffeine) may be different, we should also bear in mind that the results of the Swedish study may apply only to women.

Reference: 

Source: 

Topics: 

tags development: 

tags lifestyle: 

tags memworks: 

tags problems: 

Predicting memory loss in healthy older adults

February, 2011

Having the ‘Alzheimer’s gene’ and showing reduced brain activity during a mental task combined to correctly predict future cognitive decline in 80% of healthy elders.

In a study in which 78 healthy elders were given 5 different tests and then tested for cognitive performance 18 months later, two tests combined to correctly predict nearly 80% of those who developed significant cognitive decline. These tests were a blood test to identify presence of the ‘Alzheimer’s gene’ (APOE4), and a 5-minute fMRI imaging scan showing brain activity during mental tasks.

The gene test in itself correctly classified 61.5% of participants (aged 65-88; mean age 73), showing what a strong risk factor this is, but when taken with activity on the fMRI test, the two together correctly classified 78.9% of participants. Age, years of education, gender and family history of dementia were not accurate predictors of future cognitive decline. A smaller hippocampus was also associated with a greater risk of cognitive decline.

These two tests are readily available and not time-consuming, and may be useful in identifying those at risk of MCI and dementia.

Reference: 

Woodard, J.L.  et al. 2010. Prediction of Cognitive Decline in Healthy Older Adults using fMRI. Journal of Alzheimer’s Disease, 21 (3), 871-885.

Source: 

Topics: 

tags development: 

tags problems: 

Importance of exercise for Alzheimer's gene carriers

January, 2011

A small study suggests that physical activity may be of greater benefit to those carrying the Alzheimer’s gene in protecting against cognitive decline.

A study involving 68 healthy older adults (65-85) has compared brain activity among four groups, determined whether or not they carry the Alzheimer’s gene ApoE4 and whether their physical activity is reported to be high or low. The participants performed a task involving the discrimination of famous people, which engages 15 different functional regions of the brain. Among those carrying the gene, those with higher physical activity showed greater activation in many regions than those who were sedentary. Moreover, physically active people with the gene had greater brain activity than physically active people without the gene.

And adding to the evidence supporting the potential for exercise to lower the risk of dementia, another recent study has found that after ten years exercise (in terms of the number of different types of exercises performed and number of exercise sessions lasting at least 20 minutes) was inversely associated with the onset of cognitive impairment. The study used data from the National Long Term Care Survey.

Reference: 

Source: 

Topics: 

tags development: 

tags lifestyle: 

tags memworks: 

tags problems: 

How the Alzheimer’s gene works; implications for treatment

November, 2010

Research with genetically engineered mice shows why the apoE4 gene is so strongly associated with Alzheimer’s, and points to strategies for countering its effects.

Carriers of the so-called ‘Alzheimer’s gene’ (apoE4) comprise 65% of all Alzheimer's cases. A new study helps us understand why that’s true. Genetically engineered mice reveal that apoE4 is associated with the loss of GABAergic interneurons in the hippocampus. This is consistent with low levels of GABA (produced by these neurons) typically found in Alzheimer’s brains. This loss was associated with cognitive impairment in the absence of amyloid beta accumulation, demonstrating it is an independent factor in the development of this disease.

The relationship with the other major characteristic of the Alzheimer’s brain, tau tangles, was not independent. When the mice’s tau protein was genetically eliminated, the mice stopped losing GABAergic interneurons, and did not develop cognitive deficits. Previous research has shown that suppressing tau protein can also prevent amyloid beta from causing memory deficits.

Excitingly, daily injections of pentobarbital, a compound that enhances GABA action, restored cognitive function in the mice.

The findings suggest that increasing GABA signaling and reducing tau are potential strategies to treat or prevent apoE4-related Alzheimer's disease.

Reference: 

Source: 

Topics: 

tags development: 

tags memworks: 

tags problems: 

Low testosterone linked to Alzheimer's disease

November, 2010

Another small study supports earlier research suggesting that low testosterone is a risk factor for Alzheimer’s for older men.

A Chinese study involving 153 older men (55+; average age 72), of whom 47 had mild cognitive impairment, has found that 10 of those in the MCI group developed probable Alzheimer's disease within a year. These men also had low testosterone, high blood pressure, and elevated levels of the ApoE4 protein.

The findings support earlier indications that low testosterone is associated with increased risk of Alzheimer's in men, but it’s interesting to note the combination with high blood pressure and having the ApoE4 gene. I look forward to a larger study.

Reference: 

Chu, L-W. et al. 2010. Bioavailable Testosterone Predicts a Lower Risk of Alzheimer’s Disease in Older Men. Journal of Alzheimer's Disease, 21 (4), 1335-45.

Source: 

Topics: 

tags: 

tags development: 

tags problems: 

Vitamin B12 may reduce risk of Alzheimer's disease

November, 2010

A long-running study adds to the evidence that high levels of homocysteine increase the risk of developing Alzheimer’s, and higher levels of vitamin B12 help to bring down these levels and reduce risk.

A seven-year study involving 271 Finns aged 65-79 has revealed that increases in the level of homocysteine in the blood were associated with increasing risk of developing Alzheimer’s (each micromolar increase in the concentration of homocysteine increased the risk of Alzheimer's by 16%), while increases in the level of vitamin B12 decreased the risk (each picomolar increase in concentration of B12 reduced risk by 2%). A larger study is needed to confirm this. 17 people (6%) developed Alzheimer’s over the course of the study.

Still, these results are consistent with a number of other studies showing greater risk with higher homocysteine and lower B12. High levels of vitamin B12 are known to lower homocysteine. However, studies directly assessing the effects of B12 supplements have had mixed results. Low levels of B12 are common in the elderly.

Reference: 

Source: 

Topics: 

tags: 

tags development: 

tags lifestyle: 

tags problems: 

Heavy smoking in midlife associated with dementia in later years

November, 2010

A very large long-running study has found smoking over two packs per day in middle age more than doubled the chances of developing dementia in later life.

Data from 21,123 people, surveyed between 1978 and 1985 when in their 50s and tracked for dementia from 1994 to 2008, has revealed that those who smoked more than two packs per day in middle age had more than twice the risk of developing dementia, both Alzheimer's and vascular dementia, compared to non-smokers.

A quarter of the participants (25.4%) were diagnosed with dementia during the 23 years follow-up, of whom a little over 20% were diagnosed with Alzheimer's disease and nearly 8% with vascular dementia.

Former smokers, or those who smoked less than half a pack per day, did not appear to be at increased risk. Associations between smoking and dementia did not vary by race or sex.

Smoking is a well-established risk factor for stroke, and is also known to contribute to oxidative stress and inflammation.

Reference: 

[1934] Rusanen, M., Kivipelto M., Quesenberry C. P., Zhou J., & Whitmer R. A.
(2010).  Heavy Smoking in Midlife and Long-term Risk of Alzheimer Disease and Vascular Dementia.
Arch Intern Med. archinternmed.2010.393 - archinternmed.2010.393.

Source: 

Topics: 

tags development: 

tags lifestyle: 

tags problems: 

Pages

Subscribe to RSS - risk factors
Error | About memory

Error

The website encountered an unexpected error. Please try again later.