stroke

More evidence linking heart disease risk factors and cognitive decline

May, 2011

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.

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Individual differences in learning motor skills reflect brain chemical

April, 2011

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.

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Drug derived from curcumin may help treat stroke

March, 2011

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.

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

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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

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Compound derived from curry spice helps in stroke and TBI

January, 2011

Two new animal studies offer hope for a drug treatment for traumatic brain injury and stroke.

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

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Cognitive recovery after brain damage more complex than realized

January, 2011

Two new studies show us that recovery after brain damage is not as simple as one region ‘taking over’ for another, and that some regions are more easily helped than others.

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.

Reference: 

[2034] Voytek, B., Davis M., Yago E., Barcel F., Vogel E. K., & Knight R. T.
(2010).  Dynamic Neuroplasticity after Human Prefrontal Cortex Damage.
Neuron. 68(3), 401 - 408.

[2033] Voytek, B., & Knight R. T.
(2010).  Prefrontal cortex and basal ganglia contributions to visual working memory.
Proceedings of the National Academy of Sciences. 107(42), 18167 - 18172.

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Cognitive test distinguishes those at greater risk of stroke

February, 2010

A large long-running study has found that Swedish men in their 70s 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%.

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.

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Mediterranean diet may lower risk of brain damage

February, 2010

Seniors who were most closely following a Mediterranean-like diet were 36% less likely to have brain infarcts than those least following the diet.

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.

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The study will be presented at the American Academy of Neurology's 62nd Annual Meeting in Toronto April 10 to April 17, 2010.

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Stroke patients regain the power of speech by singing

March, 2010

People deprived of speech following a stroke were taught to sing words instead of speaking them in a technique known as 'melodic intonation therapy'.

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.

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The findings were reported at the American Association for the Advancement of Science meeting in San Diego.

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Video games help stroke victims recover motor function

March, 2010

A pilot study suggests that video games for the Nintendo Wii could help stroke victims recover fine and gross motor function after a stroke.

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.

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The research was presented February 25 at the American Stroke Association's International Stroke Conference.

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