Earlier studies have suggested that omega-3 fatty acids,  found in fatty fish such as salmon and in nuts, benefit thinking skills. A new paper in Neurology, based on a study that involved 2,157 women age 65 to 80 who were enrolled in the Women's Health Initiative clinical trials of hormone therapy,  disputes that.

The women were given annual tests of thinking and memory skills for an average of six years. Blood tests were taken to measure the amount of omega-3s in the participants' blood before the start of the study.

The researchers found no difference between the women with high and low levels of omega-3s in the blood at the time of the first memory tests. There was also no difference between the two groups in how fast their thinking skills declined over time.

"There has been a lot of interest in omega-3s as a way to prevent or delay cognitive decline, but unfortunately our study did not find a protective effect in older women. In addition, most randomized trials of omega-3 supplements have not found an effect," said study author Eric Ammann, MS, of the University of Iowa in Iowa City. "However, we do not recommend that people change their diet based on these results. Researchers continue to study the relationship between omega-3s and the health of the heart, blood vessels, and brain. We know that fish and nuts can be healthy alternatives to red meat and full-fat dairy products, which are high in saturated fats."