Friday, September 24, 2010

A new study of high-dose B vitamins suggest the rate of brain shrinkage may be slowed by treatment in elderly people with mild cognitive impairment (MCI). Overall, B vitamins given at a dose high enough to reduce homocysteine (an amino acid) by 31.7% in this trial had a "pretty dramatic effect" on the rate of brain atrophy also of about 30% compared with placebo.

The effect was greater among those subjects with the highest homocysteine levels. "The treatment actually reduced the rate of shrinkage by 53%, which is a huge effect," said Dr. Smith, the study leader. "We were absolutely delighted with this strong result."

Neuroimaging studies have established that even in the healthy elderly, the brain shrinks at a rate of about 0.5% per year. In those with Alzheimer's disease, the rate is accelerated to about 2.5% per year, and those with MCI fall somewhere in between, with an intermediate rate of about 1%.
Homocysteine has been confirmed a risk factor for brain atrophy, as well as cognitive impairment and dementia. "Since homocysteine levels can be regulated by B vitamins, because they are the main cofactors in the enzymes involved in metabolizing homocysteine, the question is, 'If you lower homocysteine by giving B vitamins, will you reduce the rate of shrinkage of the brain?'"

Of course, the big question is whether this reduction in the rate of brain atrophy translates into maintaining cognition. The trial was not big enough to answer that question statistiaclly. However, another study, NORVIT also looked at cognitive outcomes, and showed no effect of B vitamins in improving cognitive performance over 2 years in otherwise healthy elderly subjects (N Engl J Med. 2006;354:2764-2772, 2817-2819).

For now, I’m going to continue taking vitamins.

Thursday, September 16, 2010

At a recent meeting, neurologists described resting-state connectivity of brain regions associated with introspection. This network is chronically hyperactivated and hyperconnected in patients with schizophrenia. When healthy people are at rest, parts of the frontal lobes are not correlated, but in patients with schizophrenia and bipolar disorder, they are linked. This may help explain cognitive dysfunction in both disorders.

Michael Greicius, MD also addressed the default-mode network of the brain during his talk on Alzheimer's disease. The posterior regions of the default-mode network tend to overlap considerably with brain regions that show reduced metabolism in the earliest stages of Alzheimer's disease. “Using these functional connectivity approaches, our group and others have demonstrated reduced functional connectivity in the default-mode network in Alzheimer's disease, mild cognitive impairment, healthy older controls with prominent amyloid plaque burden, and healthy older carriers of the ApoE4 allele,” he said. In addition to functional changes, this brain network also appears to undergo structural changes and overlap with maps of amyloid plaque distribution (amyloid causes brain cell death in Alzheimer’s Disease).

Classically, neurologists study and describe brain anatomy whereas psychiatrists are concerned with human behavior. As new brain imaging techniques become more robust, the distinction between these fields of medicine blur.

Wednesday, September 15, 2010

There’s not been a lot of new information to discuss. But there was a recent review of the various factor believed to contribute to the delay or prevention of cognitive decline. To be included, studies had to have adult participants who were 50 years or older, drawn from general populations, and followed for at least 1 year. 127 observational studies and 22 randomized control trials (RCT), and 16 systematic reviews were reviewed. There was limited evidence to supported the benefits of selected nutritional factors or cognitive and physical activities. Factors associate with an increased risk were current tobacco use, a gene associated with Alzheimer’s Disease, and certain medical conditions. One RCT found a small, sustained benefit from cognitive training and another RCT reported that physical exercise helps to maintain cognitive function. Although the review concluded that there were few potentially beneficial factors in preventing cognitive decline, the overall quality of the evidence is low.

Friday, September 10, 2010

Cell phone use has increased dramatically since being introduced in the early 1980s. But its use has raised questions as to whether repeated low-level exposure to radiofrequency (RF) energy can damage human tissue to the point of causing malignancy. Because most users hold the cell phone against their ear, there is concern usage may cause tumors to either the ear (acoustic neuromas), salivary glands, adjacent brain (gliomas), or the tissue lining of the skull (meningiomas).

To address this question, an international study, INTERPHONE, was conducted. The study included users with at least 10 years of exposure. In addition it contained users with the greatest cumulative hours of use of any prior study, making it the largest study to date addressing this controversy. The data analysis was quite extensive, but overall the results indicate that cell phone users did not appear to have an increase in risk of either glioma or meningioma. However, there was a suggestion of an increased risk of glioma for those users who had the highest exposure levels of RF energy. This higher exposure could be from either in an increased number of calls or prolonged calls.

Wednesday, September 1, 2010

The August 19 issue of the New England Journal of Medicine reported that Tai chi may be a helpful intervention for patients with fibromyalgia. "Previous research has suggested that tai chi offers a therapeutic benefit in patients with fibromyalgia," wrote Chenchen Wang, MDl. "...[Tai chi] combines meditation with slow, gentle, graceful movements, as well as deep breathing and relaxation, to move vital energy (or qi) throughout the body. It is considered a complex, multicomponent intervention that integrates physical, psychosocial, emotional, spiritual, and behavioral elements."

66 participants were randomly assigned to receive classic Yang-style tai chi or a control intervention consisting of wellness education and stretching. In both groups, participants received 60-minute sessions twice weekly for 12 weeks. Fibromyalgia Impact Questionnaire score at the end of 12 weeks was the main study outcome, with higher scores indicating more severe symptoms. There were additional test to measure other aspects of outcome. To assess durability of the response, these tests were performed again at 24 weeks.

Improvements in the FIQ total score and quality of life in the tai chi group were clinically important. The tai chi group also fared better than the wellness intervention group in physical component scores of the Short-Form Health Survey and mental component scores. These improvements were still present at 24 weeks with no reported adverse events. Limitations of this study include lack of double blinding, lack of generalizability because treatment was delivered by a single tai chi master at a single center, and follow-up limited to 24 weeks.