It found that older adults at risk of late-onset Alzheimer's disease who consumed more omega-3 fatty acids did better than their peers on tests of cognitive flexibility.When it comes to fat, there is one type you do not want to cut back on: Omega-3 fatty acids.Two crucial ones - EPA and DHA - are primarily found in certain fish.AlA (alpha-linolenic acid), another omega-3 fatty acid, is found in plant sources such as nuts and seeds.