Fish Can Keep Mental Decline at Bay

Mackerel, salmon and herring should top your menu

FRIDAY, Jan. 30, 2004 (HealthDayNews) -- Having trouble finding those misplaced keys or the TV remote, but think you're too young for "senior moments"?

It could be because of what you eat, says new research that finds fat intake may play a role in brain functioning in middle age.

A study of 1,613 men and women between the ages of 45 and 70 in the Netherlands, which has traditionally had a diet high in fish, found the type of fat consumed plays a role in a person's mental flexibility, speed and overall functioning.

Researchers from University Medical Center Utrecht found people who ate lots of foods rich in omega-3 polyunsaturated fatty acids and consumed lots of fatty fish generally had a lower risk for impaired brain functioning (19 percent less) and speed (28 percent less), compared to those who didn't follow a similar diet.

Fatty fish include mackerel, salmon and herring, which are found in the icy waters off the northern European coastline.

"We used really sensitive cognitive tests, and it surprised me that already at that age you could see the association" between diet and mental agility, says Dr. Sandra Kalmijn, of the Julius Center for Health Sciences and Primary Care. "It convinced me and reinforced for me the link we saw between lots of fish and cognitive function."

Conversely, those with diets high in cholesterol were found at a "significantly" increased risk of impaired memory (27 percent higher) and flexibility (26 higher).

The findings appear in the Jan. 26 issue of Neurology.

The study notes that previous animal studies have also shown a cholesterol-heavy diet can lead to accumulation of B-amyloid proteins in the brain. And that may lead to the formation of amyloid plaques, which have been found in patients with Alzheimer's disease.

But a similar study released several months ago, using earlier follow-up data, showed no association between dietary fats and brain functioning.

"Yes, earlier studies have shown mixed results," acknowledges co-researcher Daan Kromhout. "Overall it's undecided -- we need more data to have a definite opinion. At the moment, we have none."

"I think the evidence is strong for the protective effects for omega-3 fatty acids," he adds, "but at this moment it is undecided for the association for the saturated fats for cognitive functions."

Kalmijn offers this dietary advice to anyone confused by the conflicting studies: "It certainly wouldn't harm you to eat more fatty fish. It's already shown to be protective of cardiovascular functions. Maybe it also keeps your brain fit."

"The issue is not solved yet, but it certainly won't harm you," she adds. "The same goes for moderating saturated fat and increased risk for reduced cognitive function."

Previous studies have shown that omega-3 oils and fatty fish also have a beneficial effect on cardiovascular functioning, while saturated fats, such as trans-fatty acids, have a detrimental impact on the heart.

Because a decline in mental skills can appear decades before the onset of Alzheimer's disease, the study says it's important to examine the effect of diet on cognitive functioning in middle age.

Alzheimer's disease affects about 4.5 million Americans, making it the most common form of dementia in the elderly, according to the Alzheimer's Association.

More information

To learn more about omega-3 fatty acids and memory, visit Tufts University. For more on Alzheimer's disease, check the Alzheimer's Association.

SOURCES: Sandra Kalmijn, M.D., Ph.D., Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, the Netherlands; Daan Kromhout, Ph.D., Division of Nutrition and Consumer Safety, University Medical Center Utrecht, the Netherlands; Jan. 26, 2004, Neurology
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