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.

Train Working Memory to Improve Brain Fitness

Learning about what kinds of cognitive training can actually help to maintain and improve your brain fitness can be confusing. Several websites promise to improve your brain fitness with online games or by way of software that you can order.

What kinds of cognitive training actually make a difference in someone’s brain functioning? Research to answer this question is in its infancy, but a number of studies have suggested that there is something special about training working memory. You use working memory when you have to keep several things in your mind and once, and then do something with them.

Think about adding two numbers that each have two digits, like 98 and 33. Remember, this problem is read aloud to you, so you can’t see the numbers, except possibly in your mind. You may know to add the 8 and 3 to get 11, but then you have to keep the 1 in mind while you add 1 (carried over) to 9 and 3. That’s working memory.

Why are people interested in working memory and brain fitness? We know it declines with age, and at least one study has shown that it can be improved with training (Jaeggi et al., 2008). Further, training working memory has been related to improvements in fluid intelligence, a key ability that underlies new learning and problem solving. And some researchers believe that working memory ability is a key part of general intelligence.

Another study showed that working memory training could change the density of neurotransmitter receptors in a part of the brain that is important for attention (McNab et al., 2009).

My colleagues and I are working on a study of working memory in older persons who are cognitive normal. Tomorrow I’ll list ways you can train working memory for little or no money.

References:

Jaeggi SM et al. (2008). Improving fluid intelligence with training on working memory. Proceedings of the National Academy of Sciences, 105, 6829-6833.

McNab F et al. (2009). Changes in cortical dopamine D1 receptor binding associated with cognitive training. Science, 323, 800-802.