Endocannabinoid system has been highlighted as one of the most relevant research topics by neurobiologists, pharmacists, basic scientists and clinicians. The association between endocannabinoids and its congeners and mood disorders is relatively recent. However, evidence from both clinical and preclinical studies is increasing and many researchers point out endocannabinoid system and particularly endocannabinoids and congeners as promising pharmacological targets.

The main objective of this study is to compare the plasma concentrations of endocannabinoids and congeners between a sample of patients with depression and a sample of control subjects, and the influence of variables such as age, body mass index, gender, severity of symptoms, and antidepressant medication.

Plasma concentrations of endocannabinoids and congeners will be analyzed in 69 patients with depression from primary care and 47 controls using mass spectrometry analysis.

Statistically significant differences in 2-arachidonoylglycerol and monoacylglycerols were found between both samples. Somatic symptoms of depression seems to be more related to these compounds that to cognitive-affective symptoms. In addition, differences between mildly and moderately depressed patients were found in concentrations of AEA, LEA, DGLEA and POEA. Patients with antidepressant medication showed higher levels of 2-AG, DGLEA and OEA.

The results of this study provide evidence supporting the hypothesis that in depression there is a dysregulation of the inflammatory signaling and, consequently the immune system. The results of this study could also support the realization of translational research to better understand the mechanisms of this widely distributed system.