PET reveals positive effects of healthy regimen

After 14 days of following healthy lifestyle strategies, participants in a study demonstrated decreased brain metabolism in working memory regions. These results suggest the brain worked more efficiently, or not as hard, to accomplish tasks.

This is the first study to show the impact of memory exercises and stress reduction used together with a healthy diet and physical exercise to improve brain and cognitive function, according to lead author Dr. Gary Small, a professor of psychiatry and biobehavioral sciences at the University of California, Los Angeles.

Previous FDG-PET studies have shown high cerebral glucose metabolic rates in volunteers as they initially learned to play a computer game. When they became proficient, however, their metabolic rate decreased. Lower brain activity with improved mental performance indicates that the brain can adapt to achieve comparable performance levels with less work.

Small and colleagues said their study suggests that such an improvement in brain efficiency may occur over relatively brief periods of intervention (Am J Geriatr Psychiatry 2006;14:538-545).

The researchers recruited 17 nondemented subjects (mean age 53 years) with mild self-reported memory complaints but normal baseline memory performance scores. Eight subjects were randomly assigned to an intervention group, which included a program combining a brain healthy diet plan, relaxation exercises, cardiovascular conditioning, and mental exercises. Remaining subjects continued their usual lifestyle routine and served as a control group

All subjects underwent FDG-PET scans at mental rest before and after the two-week regimen. Participants who followed the healthy lifestyle plan demonstrated a 5% decrease in brain metabolism in the dorsolateral prefrontal cortex, which is directly linked to working memory, compared with baseline. The control group showed no significant change in brain metabolism. Compared with the control group, healthy lifestyle plan participants also performed better in verbal fluency, a cognitive function controlled by the same brain region.

The dorsolateral prefrontal cortex mediates anxiety symptoms, and the regional metabolic reduction may in part have resulted from the intervention's relaxation exercises, according to the study. The significant change observed in the left hemisphere also is consistent with the verbal emphasis in the program's memory training exercises.

Future studies will assess specific effects of individual components of the program and determine whether a combination of healthy lifestyle strategies produces a greater effect than individual strategies, Small said.

In a previous functional MRI study, the UCLA researchers found that adults with a genetic risk for Alzheimer's disease had greater MR signal activity in the dorsolateral prefrontal cortex during a memory task compared with those without such a genetic risk. Higher MR signals at baseline correlated with lower verbal memory scores two years later (NEJM 2000;343:450-456). The researchers would like to determine whether such apparent neural compensatory responses to genetic risk would change after a lifestyle intervention such as the one used in the present study.

They cited elements of the healthy lifestyle plan:

• crossword puzzles and brainteasers

• daily walks and warmup exercises

• relaxation and visualization exercises

• five small meals a day full of omega-3 fats, antioxidants, and low-glycemic carbohydrates like whole grains

Small's new book The longevity bible: 8 essential strategies for keeping your mind sharp and your body young, builds on his previous two titles: The memory prescription: Dr. Gary Small's 14-day plan to keep your brain and body young and The memory bible: an innovative strategy for keeping your brain young.

For more information from the Diagnostic Imaging archives:

Errant enzyme may cause AD plaque

PET/CT imaging distinguishes potentially treatable dementias

Neuroimaging sharpens focus on mild cognitive impairment

Imagers seek answers for Alzheimer's diagnosis