DHA for Brain Fitness? Mixed Results

A paper in last week’s JAMA reports on a clinical trial of docosahexaenoic acid (DHA) in preventing cognitive decline in patients with Alzheimer’s disease. DHA is a component of fish oil supplements that have been recommended for the prevention of heart disease and, possibly, to prevent aging-related cognitive decline.

Results of the overall study were negative – DHA at a dose of 2 grams a day didn’t slow how much patients’ cognitive abilities declined over 18 months.

One finding of the study has been largely ignored in media reports. In a planned subgroup analysis, though, patients treated with DHA and who did not have the ApoE 4 allele had slower cognitive decline. ApoE 4 is a gene that has been associated with greater risk for having Alzheimer’s disease. It may be related to how fatty substances in the body are used by the body.

Although the findings of the main trial are negative, one subgroup may have benefited from DHA treatment.

This study thus adds to a series of studies based on observations that people who take vitamins, nonsteroidal anti-inflammatory drugs, and fish oil supplements have lower risks for Alzheimer’s disease. The logic of the trials has been to evaluate things associated with lower risk as treatments, but none has turned out to be effective.

Click here to read the full article.

Reference:

Quinn JF et al (2010). Docosahexaenoic acid supplementation and cognitive decline in Alzheimer disease. JAMA, 304, 1903-1911.

Training Affects Cerebral Blood Flow

A report from researchers now has shown that cognitive training can increase blood flow to parts of the brain critical for attention and memory. The report in Frontiers in Human Neuroscience (March 12, 2010) used functional MRI to evaluate how a training program affected gray matter thickness and resting blood flow in several cortical regions.

The intervention focused on improving healthy older adults’ ability to perform a task while subjected to audio and video distractors.The key goal was to improve participants’ ability to screen out irrelevant information while paying attention to what was important. The training worked. Participants got better at screening out distracting information. Another group completed an educational intervention; they didn’t show improvements in their ability to ignore distractors.

Functional MRI data were collected on some of the participants. They showed that participants had increased blood flow to an area in the right inferior prefrontal cortex than did control participants.This area of the cortex has been associated with the ability to sustain attention and complete several tasks simultaneously.

The significance of these findings is in showing once again that cognitive training can have a substantial impact on biological parameters in areas of the brain known to be important for cognitive function. Issues remaining include determining the best ways to train, how much and how often to train, and how much training will translate into real-world behaviors.

Reference:

Mozolic JL et al. (2010). A cognitive training intervention increases resting cerebral blood flow in health older adults. Frontiers in Human Neuroscience, March 2010, volume 4, article 16. doi: 10.3389/neuro.09.016.2010 Link to article here.