"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," study author Eric Ammann, MS, of the University of Iowa in Iowa City, said.
However, the researchers did not recommend that people change their diet based on these results.
The study involved 2,157 women age 65 to 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 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.
The study is published in journal Neurology.