So, you're concerned about your cognitive function and want to tailor what you eat to your own specific needs? If so, then I think what you cut out or avoid can be just as important as what you add in.
If you have any kind of food sentivities or a 'leaky gut,' then you won't be able to digest and absorb nutrients properly. This can lead to a whole variety of health issues, including 'brain fog,' reduced concentration, etc. An elimination diet to pinpoint the foods that are problematic for you and/or a gut-healing protocol could help.
Otherwise, omega-3's and just trying to eat a whole foods diet that reduces your overall levels of inflammation might be a good approach.