Stroke

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.

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.)

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.

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.

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.

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.

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.

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.

Following indications that the curry spice curcumin (the active ingredient in turmeric) may help protect brain cells from damage, two new studies have been testing a compound called CNB-001, derived from curcumin.

The first (rabbit) study found that CNB-001 is at least as effective as the only existing drug used to treat stroke (TPA), without the unwanted side-effect of reducing clotting in the blood vessels of the brain.

The second study found that CNB-001 dramatically reversed the behavioral deficits in both locomotion and memory in brain-injured rats. As with stroke, CNB-001 was again found to maintain the critical signaling pathways required for nerve cell survival, as well as the connections between nerve cells that are lost with the injury.

At present, there is no treatment for TBI, and only one FDA-approved drug for ischemic stroke

When stroke or brain injury damages a part of the brain controlling movement or sensation or language, other parts of the brain can learn to compensate for this damage. It’s been thought that this is a case of one region taking over the lost function. Two new studies show us the story is not so simple, and help us understand the limits of this plasticity.

In the first study, six stroke patients who have lost partial function in their prefrontal cortex, and six controls, were briefly shown a series of pictures to test the ability to remember images for a brief time (visual working memory) while electrodes recorded their EEGs. When the images were shown to the eye connected to the damaged hemisphere, the intact prefrontal cortex (that is, the one not in the hemisphere directly receiving that visual input) responded within 300 to 600 milliseconds.

Visual working memory involves a network of brain regions, of which the prefrontal cortex is one important element, and the basal ganglia, deep within the brain, are another. In the second study, the researchers extended the experiment to patients with damage not only to the prefrontal cortex, but also to the basal ganglia. Those with basal ganglia damage had problems with visual working memory no matter which part of the visual field was shown the image.

In other words, basal ganglia lesions caused a more broad network deficit, while prefrontal cortex lesions resulted in a more limited, and recoverable, deficit. The findings help us understand the different roles these brain regions play in attention, and emphasize how memory and attention are held in networks. They also show us that the plasticity compensating for brain damage is more dynamic and flexible than we realized, with intact regions stepping in on a case by case basis, very quickly, but only when the usual region fails.

A pilot study suggests that video games for the Nintendo Wii could help stroke victims recover fine motor function (such as finger dexterity) and gross motor function (such as arm movements) two months after a stroke. The ten patients randomly assigned to playing these games for about six hours over the course of two weeks showed significantly better recovery, and none of the adverse effects (like nausea or dizziness) that were reported in the other group assigned to recreational games such as cards or the block-stacking game Jenga. A clinical trial is now underway.

And in another pilot study, people deprived of speech following a stroke were taught to sing words instead of speaking them in a technique known as 'melodic intonation therapy'. Brain scans also showed functional and structural changes in the undamaged hemisphere after they had received the therapy. Doctors are now testing the therapy in 30 stroke patients to assess how many people who lose their speech after a stroke would benefit.

A 12-year study following the drinking and smoking habits of 22,524 people aged 39-79 has found that in non-smokers, people who consumed moderate amounts of alcohol were 37% less likely to develop stroke than non-drinkers. This association was not found among smokers. The finding may explain the inconsistency in previous studies into the relationship between light to moderate drinking and stroke.

Following on from studies showing that a Mediterranean-like diet may be associated with a lower risk of Alzheimer's disease and may lengthen survival in people with Alzheimer's, a six-year study of 712 New Yorkers has revealed that those who were most closely following a Mediterranean-like diet were 36% less likely to have brain infarcts (small areas of dead tissue linked to thinking problems), compared to those who were least following the diet. Those moderately following the diet were 21% less likely to have brain damage. The association was comparable to the effects of high blood pressure — that is, not eating a Mediterranean-like diet was like having high blood pressure. The Mediterranean diet includes high intake of vegetables, legumes, fruits, cereals, fish and monounsaturated fatty acids such as olive oil; low intake of saturated fatty acids, dairy products, meat and poultry; and mild to moderate amounts of alcohol.

A long-running study involving 930 70-year-old Swedish men has found that those who were among the bottom 25% on the Trail Making Test B were three times more likely to have a stroke or a brain infarction compared to those in the top 25%. Performance on the Trail Making Test A and the MMSE did not predict brain infarction or stroke. Test B measures the ability to execute and modify a plan, while Test A measures attention and visual-motor abilities, and the MMSE is a standard test of general cognitive decline.

A study involving 54 older adults (55-80), who possessed at least one risk factor for a stroke, found that those with white matter damage caused by silent strokes reported poor attentiveness and being distracted more frequently on day-to-day tasks. Despite these complaints, about half of these people scored within the normal range on tests of attention and executive function.

It’s suggested that adults who notice that they frequently lose their train of thought or often become sidetracked may in fact be displaying early symptoms of cerebral small vessel disease.

"Silent" strokes are so-called because they don’t have obvious effects as seen with an overt stroke. Typically, they’re not diagnosed until the damage has accumulated to such an extent that effects are seen, or by chance through MRI scans.

https://www.eurekalert.org/pub_releases/2019-02/bcfg-apt020419.php

Data from the large and very long-running Framingham Heart Study has revealed that people who drink sugary drinks frequently are more likely to have poorer memory, smaller overall brain volume, and a significantly smaller hippocampus. Moreover, a second study found that those who drank diet soda daily were almost three times as likely to develop stroke and dementia over a 10-year period, compared to those who didn’t – suggesting that substituting artificial sweeteners for the sugar doesn’t make matters better.

Age, smoking, diet quality, and other factors were taken into account, but the analysis couldn’t completely control for preexisting conditions like diabetes. Diabetics tend to drink more diet soda on average, as a way to limit their sugar consumption, and some of the correlation between diet soda intake and dementia may be due to diabetes, a known risk factor for dementia.

Data from 23,572 Americans from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study has revealed that those who survived a stroke went on to have significantly faster rates of cognitive decline as they aged.

Participants, who were aged 45 years or older, had no history of cognitive impairment at the beginning of the population-based study. Over the next five to seven years, 515 of them (2%) had a stroke.

Stroke was associated with an acute decline in global cognition, new learning, and verbal memory. Those who had a stroke showed faster declines in global cognition and executive function (but not new learning nor verbal memory) over the next years.

Global cognition was assessed using the Six-Item Screener [SIS]; new learning by the Consortium to Establish a Registry for Alzheimer Disease Word-List Learning; verbal memory by the Word-List Delayed Recall; executive function by the Animal Fluency Test.

The findings suggest a need for better long-term follow-up care for stroke survivors, including therapy to retain or even regain cognitive ability.

http://www.eurekalert.org/pub_releases/2015-07/uomh-mt070715.php

As we all know, people are living longer and obesity is at appalling levels. For both these (completely separate!) reasons, we expect to see growing rates of dementia. A new analysis using data from the long-running Framingham Heart Study offers some hope to individuals, however.

Looking at the rate of dementia during four distinct periods in the late 1970s, late 1980s, 1990s, and 2000s, using data from 5205 older adults (60+), the researchers found that there was a progressive decline in the incidence of dementia at a given age, with an average reduction of 20% per decade since the 1970s (22%, 38%, and 44% during the second, third, and fourth epochs, respectively).

There are two important things to note about this finding:

• the decline occurred only in people with a high school education and above
• the decline was more pronounced with dementia caused by vascular diseases, such as stroke.

The cumulative risk over five years, adjusted for age and gender, were:

• 3.6 per 100 persons during the first period (late 1970s and early 1980s)
• 2.8 per 100 persons during the second period (late 1980s and early 1990s)
• 2.2 per 100 persons during the third period (late 1990s and early 2000s)
• 2.0 per 100 persons during the fourth period (late 2000s and early 2010s).

Part of the reason for the decline is put down to the decrease in vascular risk factors other than obesity and diabetes, and better management of cardiovascular diseases and stroke. But this doesn't completely explain the decrease. I would speculate that other reasons might include:

• increased mental stimulation
• improvements in lifestyle factors such as diet and exercise
• better health care for infectious and inflammatory conditions.

The finding is not completely unexpected. Recent epidemiological studies in the U.S., Canada, England, the Netherlands, Sweden and Denmark have all suggested that “a 75- to 85-year-old has a lower risk of having Alzheimer’s today than 15 or 20 years ago.” Which actually cuts to the heart of the issue: individual risk of dementia has gone down (for those taking care of their brain and body), but because more and more people are living longer, the numbers of people with dementia are increasing.

http://www.futurity.org/dementia-rates-decline-1119512-2/

http://www.scientificamerican.com/article/is-dementia-risk-falling/

A pilot study involving 106 participants of the Rush Memory and Aging Project who had experienced a stroke followed participants for an average of 5.9 years, testing their cognitive function and monitoring their eating habits using food journals. It was found that those whose diets scored highest on the MIND (Mediterranean-DASH Diet Intervention for Neurodegenerative Delay) diet score had substantially slower rates of cognitive decline than those who scored lowest. The estimated effect of the diet remained strong even after taking into account participants' level of education and participation in cognitive and physical activities. Those who instead scored high on the Mediterranean or DASH diets did not show the same slower decline.

Both the Mediterranean and DASH diets have been shown to be protective against coronary artery disease and stroke, but this finding suggests the MIND diet is better for overall brain health.

The MIND diet is a hybrid of the Mediterranean and DASH (Dietary Approaches to Stop Hypertension) diets. It has 15 components: 10 “brain-healthy food groups” and five unhealthy groups (red meat, butter, cheese, pastries and sweets, and fried or fast food).

To adhere to the MIND diet, you need to

• eat at least three daily servings of whole grains
• eat a green leafy vegetable and one other vegetable every day
• drink a regular glass of wine
• snack most days on nuts
• have beans every other day or so
• eat poultry and berries at least twice a week
• eat fish at least once a week
• limit butter to less than 1 1/2 teaspoons a day
• eat less than 5 servings a week of sweets and pastries
• eat less than one serving per week of whole fat cheese, and fried or fast food.

The researchers stress that this is a preliminary study, observational only. They are currently seeking participants for a wider, intervention study.

https://www.eurekalert.org/pub_releases/2018-01/rumc-mdm012418.php

Perivascular spaces are fluid-filled spaces around the cerebral small vessels, commonly seen on brain scans in older adults. They have been thought to be harmless, but a new study challenges this belief.

The study, which looked at older adults who have not yet developed dementia, showed that different markers of small vessel disease reflect distinct pathways of injury. Well-studied markers of small vessel disease include white matter hyperintensities, infarcts and microbleeds, and the most frequent associations in the study unsurprisingly linked white matter hyperintensities and cognition, including language, information processing speed, executive functioning and visuospatial skills.

Much more surprisingly, though, the next most frequent links were between enlarged perivascular spaces and information processing speed and executive functioning.

https://www.eurekalert.org/pub_releases/2019-03/vumc-sv032019.php