Omega-3 fatty acid levels are lower in the brains of people with bipolar disorder

By John Murphy, MDLinx
Published November 25, 2015

Key Takeaways

People with bipolar disorder have a lower level of an omega-3 fatty acid in the brain. Increasing this particular omega-3 fatty acid—eicosapentaenoic acid (EPA)—might have a beneficial effect on symptoms of bipolar disorder, researchers suggested in a study published the November 2015 issue of the journal Bipolar Disorders.

The researchers cautioned that it’s too soon to recommend dietary changes or omega-3 supplementation until further studies are carried out.

In this study, researchers compared plasma concentrations of 9 fatty acids in 27 people with symptomatic bipolar disorder and 31 healthy control subjects. They studied plasma concentrations because unesterified (free) fatty acids pass through the blood-brain barrier into the brain more easily than the esterified (bound) ones; thus the unesterified plasma concentration is the form that represents fatty acid metabolism in the brain.

The researchers calculated the ratios of several of the fatty acids in comparison to one another. They also collected self-reported information on fatty acid consumption and bipolar medication use.

Results showed the ratio of unesterified EPA to esterified EPA was lower in those with bipolar disorder than in control subjects. “This means that the availability of omega-3 in the body is lower in bipolar subjects,” said Erika Saunders, MD, Associate Professor and Chair of Psychiatry at Penn State College of Medicine, in Hershey, PA.

The study also showed the ratio of unesterified to esterified EPA correlated with clinical bipolar symptoms, specifically mania and tendency towards suicide. However, the researchers did not find altered ratios of omega-3 to omega-6 fatty acids in bipolar subjects.

Omega-3 and omega-6 fatty acids are molecular modulators of neurotransmission and inflammation. “Omega-3 and omega-6 fatty acids can shift the balance of inflammation, which we think is important in bipolar disorder,” Dr. Saunders said, although she added that it’s too early to advise dietary changes or omega-3 supplementation.

Bipolar and healthy patients reported no difference in fatty acid consumption. “Is that because we only included certain foods in the survey? Or is it because people couldn’t accurately recall what they were eating?” Dr. Saunders asked.

Another possibility is that there may be differences in how healthy people and people with bipolar disorder convert fatty acids from one form to another, she added. Drugs that treat bipolar disorder are known to affect these conversions, but no association was found between fatty acid levels or ratios and self-reported medication use in the study.

Further studies of the specific signaling pathways and lipid mediators that link omega-3 and omega-6 fatty acids to the pathogenesis of bipolar disorder may lead to development of targeted medication and dietary treatments, the researchers noted.

“We are actively pursuing the next step in this line of inquiry to get to the point where we know what changes in diets are going to help people with bipolar disorder so they can have another option beyond the medications that are currently available,” Dr. Saunders said.

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