The research, published in the American Journal of Clinical Nutrition, found that walnut consumption by healthy, elderly adults had little effect on cognitive function over two years, but it had greater effect on elderly adults who had smoked more and had a lower baseline neuropsychological test scores.
"While this was a minor result, it could lead to better outcomes when conducted over longer periods of time," said study researcher Joan Sabate from Loma Linda University in the US.
"Further investigation is definitely warranted based on our findings, especially for disadvantaged populations, who may have the most to gain from incorporating walnuts and other nuts into their diet," Sabate added.
The study examined nearly 640 free-living elders in Loma Linda, California, US, and in Barcelona, Catalonia, Spain. For two years, the test group included walnuts in their daily diet, and the control group abstained from walnuts.
Walnuts contain omega-3 fatty acids and polyphenols, which have previously been found to counteract oxidative stress and inflammation, both of which are drivers of cognitive decline, the researchers said.
According to the researchers, this was the largest and most well-controlled trial ever conducted on the effects of nuts on cognition.
Sabate and his research team were the first to discover the cholesterol-lowering effect of nut consumption specifically walnuts with lowering blood cholesterol. Findings were first published in the New England Journal of Medicine in 1993.
( With inputs from IANS )