Could serum endocannabinoid and N-acylethanolamine levels be important in bipolar disorder?

The endocannabinoid system (ECS) is a critical important neuromodulatory system that interacts with many neurohormonal and neurotransmitter systems in the brain. It plays a pivotal role in emotional responses and mood regulation. The ECS is related with psychotic disorders, depression, anxiety and autism. In this study, we aimed to investigate whether there is any relationship between endocannabinoid and N-acylethanolamine levels with bipolar disorder.

Seventy-nine patients with bipolar disorder diagnosis, who are in the euthymic period, were included in the study. Clinical characteristics, symptoms and serum endocannabinoid and N-acylethanolamine levels were compared. Endocannabinoid and N-acylethanolamine levels were evaluated using liquid chromatography-tandem mass spectrometry.

In total of 79 patients, 44 (55.69%) were females and 35 (44.30%) were males. The mean age of the patients was 42.40 ± 1.10 years. Palmitoylethanolamide (PEA) levels were higher and oleoylethanolamide and 2-arachidonyl glycerol levels were lower in patients who had at least one depressive episode during their life-time illness than in patients who had no depressive episode while arachidonyl ethanolamide levels were unchanged.

PEA levels were correlated with the history and frequency of depressive episodes and the history of depressive symptoms in patients with bipolar disorder.