DHA and vitamin D lower risk for mental decline

Docosahexaenoic acid (DHA) reduced risk for Alzheimer’s disease (AD) and mental decline (dementia), and older adults with adequate levels of vitamin D had better mental abilities than those with lower levels, in three new studies.

Researchers conducting the Framingham Heart Study followed 899 men and women, median age 76, for 9.1 years after first measuring blood plasma levels of DHA to determine risk for AD and dementia. At the end of the study, there were 99 new cases of dementia, including 71 cases of AD, which is the most common type. Scientists adjusted for other factors including age, sex, education, genetic defect (Apolipoprotein E epsilon-4 Allele), and inflammation (homocysteine), and found that, compared to those with lower DHA levels, those with the highest DHA levels—the top 25% of the group—were 47% less likely to develop any type of dementia and were 39% less likely to develop AD. Doctors noted that those with the highest DHA levels consumed an average of 180 mg of DHA per day and ate an average of three servings of fish per week. DHA is an omega-3 fatty acid typically found in fish, particularly fatty fish.

In a vitamin D study, researchers reviewed the medical charts of 32 older adults who had reported memory problems and who had taken the Mini Mental State Examination (MMSE), which tests attention, recall, and the ability to follow verbal and written commands. Those with higher blood serum vitamin D levels had better MMSE scores than did those with lower vitamin D levels.

In another vitamin D study, researchers recruited 80 older adults, 40 of whom had mild AD and 40 of whom were mentally healthy, and found that average vitamin D levels were low, and were abnormally low (below 20 ng/mL) in 58% of participants. Compared to those with adequate levels of vitamin D, those with low vitamin D levels were more likely to be depressed and to perform mental functions poorly, with or without AD. 

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