Want to stay smart into your old age? Consider eating more oily fish or taking fish oil supplements, suggest researchers from Scotland. They found that people who eat oily fish or take fish oil supplements score 13% higher in IQ tests and are less likely to show early signs of Alzheimer’s disease.

The new study involved data on more than 300 people who had taken part in a national IQ survey in 1947, when they were aged 11. They were tested again in 2000 or 2001 when they were aged 64. The researchers gauged omega-3 levels from diet and supplement use, and also tested plasma levels of omega-3.

They found that cognitive function in the 64-year-olds was higher if they were supplement users than if they did not take supplements. After adjustment for childhood IQ, tests for mental speed found food supplement users to have a higher score.

Lawrence Whalley, head of the research team, says there’s evidence that fish oils slow the aging of the brain by reducing inflammation.

“The big difference we found was not in memory but in mental speed,” he said. “The brains of fish oil users seemed to be faster. There was a strong relationship between mental test scores and the omega-3 content in the blood.”

American Journal of Clinical Nutrition;80(6):1650-1657