Study author Eric Ammann of the University of Iowa in Iowa City said the study involved 2,157 women ages 65-80 who were enrolled in the Women's Health Initiative clinical trials of hormone therapy. 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 study, published in the journal Neurology, 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.
"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," Ammann said in a statement.
"We know that fish and nuts can be healthy alternatives to red meat and full-fat dairy products, which are high in saturated fats."