Evening primrose oil has been shown to help lower blood cholesterol, which is good for your circulatory system and thus good for your brain. Some studies have also shown that it helps enhance memory and can calm hyperactive mental states, although research regarding its usefulness in treating attention deficit hyperactivity disorder (ADHD) has been mixed. Swedish studies, though preliminary, are relating evening primrose oil to an antioxidant that counteracts the formation of free radicals, which are destructive to brain health. If you have seizures or schizophrenia and take medications to treat it or take blood thinners or blood pressure medication, check with your healthcare provider before taking primrose oil supplements.