stroke

Moderate exercise cuts women's stroke risk

Data from 133,479 women in the California Teachers Study has found that those who reported doing moderate physical activity (such as brisk walking) in the three years before enrolling in the study were 20% less likely to suffer a stroke than women who reported no activity. More strenuous activity didn’t further reduce risk.

How stress increases your risk for stroke and heart attack

A study in which 157 healthy adult volunteers were asked to regulate their emotional reactions to unpleasant pictures, has found that those who showed greater brain activation when regulating their negative emotions also had higher blood levels of interleukin-6 (a marker for inflammation) and increased thickness of the carotid artery wall (a marker of atherosclerosis).

The finding helps explain why stress increases the risk for stroke and heart attack.

Fiber in your diet reduces stroke risk

Fruit, Vegetables and Grain

Analysis of eight studies on diet and stroke published between 1990 and 2012 has found that risk of first-time stroke dropped with every 7g increase in total daily fibre. That amount of fibre is contained in a bowl of wholewheat pasta plus two servings of fruit or vegetables.

Insufficient data is available to say whether soluble or insoluble fibre is better. The studies came from the United States, northern Europe, Australia, and Japan.

Severe, rapid memory loss linked to future, fatal strokes

A large, long-running study has revealed that older adults who suffered a fatal stroke showed significantly faster cognitive decline in the years preceding the stroke compared to stroke survivors and stroke-free adults.

A ten-year study following 12,412 middle-aged and older adults (50+) has found that those who died after stroke had more severe memory loss in the years before stroke compared to those who survived stroke and those who didn't have a stroke.

Participants were tested every two years, using a standard word-recall list to measure memory loss (or caregiver assessment for those whose memory loss was too severe). During the decade of the study, 1,027 participants (8.3%) survived a stroke, 499 (4%) died after stroke, and 10,886 (87.7%) remained stroke-free over the study period.

Before having a stroke, those who later survived a stroke had worse average memory than similar individuals who never had a stroke, however their rate of memory decline was similar (0.034 and 0.028 points per year, respectively). Those who later died after a stroke, on the other hand, showed significantly faster memory decline (0.118 points per year).

Whether this is because those who die after stroke have a more compromised brain prior to the stroke, or because greater memory impairment makes people more vulnerable in the wake of a stroke, cannot be told from this data (and indeed, both factors may be involved).

Among survivors, stroke had a significant effect on memory decline, with memory scores dropping an average of 0.157 points at the time of the stroke — an amount equivalent to around 5.6 years of memory decline in similarly-aged stroke-free adults. However, in subsequent years, decline was only a little greater than it had been prior to the stroke (0.038 points per year).

(You can see a nice graph of these points here.)

Reference: 

Wang, Q., Capistrant, B.D., Ehntholt, A. & Glymour, M.M. 2012. Abstract 31: Rate of Change in Memory Functioning Before and After Stroke Onset. Presented at the American Stroke Association's International Stroke Conference 2012. http://stroke.ahajournals.org/cgi/content/meeting_abstract/43/2_MeetingAbstracts/A31?sid=960f2015-06d1-478f-8c03-c00994d35f2c

Walking speed and grip strength may predict dementia, stroke risk

More evidence comes for a link between lower physical fitness and increased risk of dementia in a large study that extends earlier findings to middle-aged and younger-old.

Following on from research showing an association between lower walking speed and increased risk of dementia, and weaker hand grip strength and increased dementia risk, a large study has explored whether this association extends to middle-aged and younger-old adults.

Part of the long-running Framingham study, the study involved 2,410 men and women with an average age of 62, who underwent brain scans and tests for walking speed, hand grip strength and cognitive function. During the follow-up period of up to 11 years, 34 people (1.4%) developed dementia (28 Alzheimer’s) and 79 people (3.3%) had a stroke.

Those who had a slower walking speed at the start of the study were one-and-a-half times more likely to develop dementia compared to people with faster walking speed, while stronger hand grip strength was associated with a 42% lower risk of stroke or transient ischemic attack in people over age 65.

Slower walking speed and weaker hand grip strength were also associated with lower brain volume and poorer cognitive performance. Specifically, those with slower walking speed scored significantly worse on tests of visual reproduction, paired associate learning, executive function, visual organization, and language (Boston Naming test). Higher hand grip strength was associated with higher scores on tests of visual reproduction, executive function, visual organization, language and abstraction (similarities test).

While the nature of the association is not yet understood, the findings do seem to support the benefits of physical fitness. At the least, these physical attributes can serve as pointers to the need for more investigation of an older person’s brain health. But they might also serve as a warning to improve physical fitness.

Reference: 

Camargo, E.C., Beiser, A., Tan, Z.S., Au, R., DeCarli, C., Pikula, A., Kelly-Hayes, M., Kase, C., Wolf, P. & Seshadri, S. 2012. Walking Speed, Handgrip Strength and Risk of Dementia and Stroke: The Framingham Offspring Study. To be presented April 25 at the American Academy of Neurology's 64th Annual Meeting in New Orleans.

How neighborhood status affects cognitive function in older adults

New research confirms the correlation between lower neighborhood socioeconomic status and lower cognitive function in older adults, and accounts for most of it through vascular health, lifestyle, and psychosocial factors.

In the last five years, three studies have linked lower neighborhood socioeconomic status to lower cognitive function in older adults. Neighborhood has also been linked to self-rated health, cardiovascular disease, and mortality. Such links between health and neighborhood may come about through exposure to pollutants or other environmental stressors, access to alcohol and cigarettes, barriers to physical activity, reduced social support, and reduced access to good health and social services.

Data from the large Women’s Health Initiative Memory Study has now been analyzed to assess whether the relationship between neighborhood socioeconomic status can be explained by various risk and protective factors for poor cognitive function.

Results confirmed that higher neighborhood socioeconomic status was associated with higher cognitive function, even after individual factors such as age, ethnicity, income, education, and marital status have been taken into account. A good deal of this was explained by vascular factors (coronary heart disease, diabetes, stroke, hypertension), health behaviors (amount of alcohol consumed, smoking, physical activity), and psychosocial factors (depression, social support). Nevertheless, the association was still (barely) significant after these factors were taken account of, suggesting some other factors may also be involved. Potential factors include cognitive activity, diet, and access to health services.

In contradiction of earlier research, the association appeared to be stronger among younger women. Consistent with other research, the association was stronger for non-White women.

Data from 7,479 older women (65-81) was included in the analysis. Cognitive function was assessed by the Modified MMSE (3MSE). Neighborhood socioeconomic status was assessed on the basis of: percentage of adults over 25 with less than a high school education, percentage of male unemployment, percentage of households below the poverty line, percentage of households receiving public assistance, percentage of female-headed households with children, and median household income. Around 87% of participants were White, 7% Black, 3% Hispanic, and 3% other. Some 92% had graduated high school, and around 70% had at least some college.

Reference: 

[2523] Shih, R. A., Ghosh-Dastidar B., Margolis K. L., Slaughter M. E., Jewell A., Bird C. E., et al. (2011).  Neighborhood Socioeconomic Status and Cognitive Function in Women. Am J Public Health. 101(9), 1721 - 1728.

Previous:

Lang IA, Llewellyn DJ, Langa KM, Wallace RB, Huppert FA, Melzer D. 2008. Neighborhood deprivation, individual socioeconomic status, and cognitive function in older people: analyses from the English Longitudinal Study of Ageing. J Am Geriatr Soc., 56(2), 191-198.

Sheffield KM, Peek MK. 2009. Neighborhood context and cognitive decline in older Mexican Americans: results from the Hispanic Established Populations for Epidemiologic Studies of the Elderly. Am J Epidemiol., 169(9), 1092-1101.

Wight RG, Aneshensel CS, Miller-Martinez D, et al. 2006. Urban neighborhood context, educational attainment, and cognitive function among older adults. Am J Epidemiol., 163(12), 1071-1078.

Moderate to intense exercise may protect the brain in old age

Moderate but not light exercise was found to help protect the brain from brain infarcts in some older adults, but not all.

Another study showing the value of exercise for preserving your mental faculties in old age. This time it has to do with the development of small brain lesions or infarcts called "silent strokes." Don’t let the words “small” and “silent” fool you — these lesions have been linked to memory problems and even dementia, as well as stroke, an increased risk of falls and impaired mobility.

The study involved 1,238 people taken from the Northern Manhattan Study, a long-running study looking at stroke and vascular problems in a diverse community. Their brains were scanned some six years after completing an exercise questionnaire, when they were an average of 70 years old. The scans found that 16% of the participants had these small brain lesions.

Those who had reported engaging in moderate to intense exercise were 40% less likely to have these infarcts compared to people who did no regular exercise. Depressingly, there was no significant difference between those who engaged in light exercise and those who didn’t exercise (which is not to say that light exercise doesn’t help in other regards! a number of studies have pointed to the value of regular brisk walking for fighting cognitive decline). This is consistent with earlier findings that only the higher levels of activity consistently protect against stroke.

The results remained the same after other vascular risk factors such as high blood pressure, high cholesterol and smoking, were accounted for. Of the participants, 43% reported no regular exercise; 36% engaged in regular light exercise (e.g., golf, walking, bowling or dancing); 21% engaged in regular moderate to intense exercise (e.g., hiking, tennis, swimming, biking, jogging or racquetball).

However, there was no association with white matter lesions, which have also been associated with an increased risk of stroke and dementia.

Moreover, this effect was not seen among those with Medicaid or no health insurance, suggesting that lower socioeconomic status (or perhaps poorer access to health care) is associated with negative factors that counteract the benefits of exercise. Previous research has found that lower SES is associated with higher cardiovascular disease regardless of access to care.

Of the participants, 65% were Hispanic, 17% non-Hispanic black, and 15% non-Hispanic white. Over half (53%) had less than high school education, and 47% were on Medicaid or had no health insurance.

More evidence linking heart disease risk factors and cognitive decline

Another study confirms that cardiovascular risk factors are also risk factors for cognitive decline.

A study involved 117 older adults (mean age 78) found those at greater risk of coronary artery disease had substantially greater risk for decline in verbal fluency and the ability to ignore irrelevant information. Verbal memory was not affected.

The findings add to a growing body of research linking cardiovascular risk factors and age-related cognitive decline, leading to the mantra: What’s good for the heart is good for the brain.

The study also found that the common classification into high and low risk groups was less useful in predicting cognitive decline than treating risk as a continuous factor. This is consistent with a growing view that no cognitive decline is ‘normal’, but is always underpinned by some preventable damage.

Risk for coronary artery disease was measured with the Framingham Coronary Risk Score, which uses age, cholesterol levels, blood pressure, presence of diabetes, and smoking status to generate a person's risk of stroke within 10 years. 37 (31%) had high scores. Age, education, gender, and stroke history were controlled for in the analysis.

Reference: 

Gooblar, J., Mack, W.J., Chui, H.C., DeCarli, C., Mungas, D., Reed, B.R. & Kramer, J.H. 2011. Framingham Coronary Risk Profile Predicts Poorer Executive Functioning in Older Nondemented Adults. Presented at the American Academy of Neurology annual meeting on Tuesday, April 12, 2011.

Individual differences in learning motor skills reflect brain chemical

An imaging study demonstrates that people who are quicker at learning a sequence of finger movements have lower levels of the inhibitory chemical GABA.

What makes one person so much better than another in picking up a new motor skill, like playing the piano or driving or typing? Brain imaging research has now revealed that one of the reasons appears to lie in the production of a brain chemical called GABA, which inhibits neurons from responding.

The responsiveness of some brains to a procedure that decreases GABA levels (tDCS) correlated both with greater brain activity in the motor cortex and with faster learning of a sequence of finger movements. Additionally, those with higher GABA concentrations at the beginning tended to have slower reaction times and less brain activation during learning.

It’s simplistic to say that low GABA is good, however! GABA is a vital chemical. Interestingly, though, low GABA has been associated with stress — and of course, stress is associated with faster reaction times and relaxation with slower ones. The point is, we need it in just the right levels, and what’s ‘right’ depends on context. Which brings us back to ‘responsiveness’ — more important than actual level, is the ability of your brain to alter how much GABA it produces, in particular places, at particular times.

However, baseline levels are important, especially where something has gone wrong. GABA levels can change after brain injury, and also may decline with age. The findings support the idea that treatments designed to influence GABA levels might improve learning. Indeed, tDCS is already in use as a tool for motor rehabilitation in stroke patients — now we have an idea why it works.

Reference: 

[2202] Stagg, C.  J., Bachtiar V., & Johansen-Berg H. (2011).  The Role of GABA in Human Motor Learning. Current Biology. 21(6), 480 - 484.

Drug derived from curcumin may help treat stroke

More evidence for the value of the curry spice curcumin comes from animal studies indicating a curcumin-derived drug may help treat stroke.

A new molecular compound derived from curcumin (found in turmeric) holds promise for treating brain damage caused by stroke. Turmeric has a long history of use in Ayurvedic and Chinese traditional medicine. However, curcumin has several important drawbacks as far as treating stroke is concerned — mainly because it can’t cross the blood-brain barrier. The new compound can.

In rabbit experiments, the drug was effective when administered up to an hour after stroke, which correlates with about three hours in humans. This is the same time frame for which tPA — the only drug currently approved for ischemic stroke — is currently approved.

The new drug is expected to move to human clinical trials soon.

Reference: 

Paul A. Lapchak presented these findings at the American Heart Association International Stroke Conference in Los Angeles on February. 9.

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