There are still plenty of questions about whether evening primrose oil can help treat brain-related conditions like hyperactivity, attention deficit hyperactivity disorder (ADHD), multiple sclerosis, depression, schizophrenia and Alzheimer's disease.
In one study involving psychiatric patients with tardive dyskinesia (abnormal, involuntary movements) who were given primrose oil for four months, researchers found the oil did nothing to stop the patients' involuntary movements, but did help improve their memory and calm their mental state [source: Hudson]. In studies of primrose oil's impact on children with attention-deficit/hyperactivity disorder (ADHD), the results have been mixed [source: Mayo Clinic].
The reason researchers even consider evening primrose oil for treating these types of conditions goes back to our friend, GLA. The importance of GLA, an omega-6 fatty acid also found in borage seeds and black current seeds, is that the body converts it to prostaglandin E1, which regulates body activity, including brain functioning [source: Schmidt].
Prostaglandin E1, considered a "messenger" in the brain, is vital to regulating nerve impulses -- one reason some experts believe that increasing prostaglandin E1 in the brain can improve things like memory, mood, impulse control and concentration [source: Schmidt].
But like all the alleged health benefits of evening primrose oil, the jury is still out. For more on the research that has been done thus far, see the links on the next page.