I’m doing my best to build a first-class brain for my son and I work hard to keep all of our minds lubed. But nothing, even the most tenderly nurtured neurons, lasts forever. With my current fuzz, I fear eventually losing myself (or my husband) to dementia, and I wanted to know how to sandbag my family against it. So I called David Smith, professor emeritus of pharmacology and head of Oxford University’s 20-year-old Oxford Project to Investigate Memory and Aging (OPTIMA), which studies nongenetic risk factors (a.k.a. environmental factors) that cause Alzheimer’s disease. His words made me happy: “It’s my personal belief that we will be able to prevent a large proportion of Alzheimer’s disease in the world.”
Smith sees parallels between Alzheimer’s disease and heart disease—an illness whose prevalence has decreased around 60 percent over the past 40 years, largely because of preventive measures taken at a societal, level such as reducing smoking, increasing exercise, eating well and taking drugs to reduce cholesterol and blood pressure. “If we can find what the risk factors are for Alzheimer’s disease, we can have a similar success.”
Unfortunately, no one yet knows what all these risk factors are, but observational studies are beginning to yield clues: it seems the same things that are good for the heart may also be good for the brain. The connection makes intuitive sense: Alzheimer’s disease likely results in part from the accumulation of so-called senile plaques—abnormal brain proteins called A-beta that many scientists think trigger inflammation and oxidation, damaging neurons. If a person has atherosclerosis, their vessels are gunky and inefficient, resulting in fewer nutrients and less oxygen supplying the brain and fewer waste products leaving it, thus exacerbating Alzheimer’s disease.
Smith was particularly interested in fish because observational studies have shown a strong link between high fish intake and a reduced risk of full-blown Alzheimer’s disease. He wanted to know if eating fish regularly could also help people improve their brain power. So he called up colleague Helga Refsum, a professor of nutrition at the University of Oslo who leads the Hordaland Health Study—one part of a huge national project that gathers extremely detailed information about people’s lives and charts cardiovascular disease all over Norway. The county of Hordaland is on the sea, and people there eat lots of fish. Smith found that, of 2,031 healthy Hordalanders aged 70 to 74, those who ate more than a two-ounce serving per week of any type of fish (not just the fatty, DHA-packed variety) scored much higher on cognitive tests than those who ate less.
I asked Smith how it could be that all types of seafood are linked to improved cognitive function, since every study I’ve ever seen points to omega-3s like DHA as the key brain-boosting component. “Of course, the fatty acids are a strong candidate,” he says, “But it may be something else. Fish is very rich in niacin; there have been reports that niacin intake is related to better cognition in the elderly. Fish is also a good source of vitamin B12.” Because the aging body is less able to absorb B vitamins, particularly B12, he explains, the elderly often have low levels, which has been associated with poorer cognitive function. “So there are several candidates in fish and we want to tease them out.”