Genetic implications of the endocannabinoid system in anxiety disorders versus depressive disorders: is there any evidence for the continuum hypothesis?

Anxiety disorders are among the most common psychiatric disorders with lifetime prevalence up to 25%. Preclinical studies point towards a series of candidate genes, including several genes from the endocannabinoid system, which are related to anxiety behavior in animals but could, therefore, also play an important pathophysiological role in humans. Besides anxiety disorders, anxiety is a common cardinal symptom in depression, leading to the hypothesis that there might be an overlap not only on the symptomatic but also on the genetic level. The aim of this study, therefore, was to perform an endocannabinoid system overview analysis of genetic effects in anxiety and depressive disorders including several phenotypes. We genotyped 42 SNPs in six genes related to the endocannabinoid system and their respective receptors in 180 patients with syndromal panic attacks, in 763 patients with depressive disorder and in 780 controls. Genotyping was performed using the MassArray® system (Sequenom™; CA). SNPs were selected from public (dbSNP) and private (Celera) databases. Patients were only included when meeting DSM-IV criteria for specific anxiety or depressive disorder. First results indicate significant effects of three genes in the anxiety group and two genes in the depressive group. Furthermore, in one gene we found significant effects over both groups. The preliminaty results suggest a possible role of endocannabinoid system for both, depressive and anxiety disorders.