The Endocannabinoid System and Stress

Introduction One of the environmental factors that precipitates and exacerbates mental illnesses, including depression, anxiety disorders, and substance abuse, is repeated life stress. For example, homotypic stressors that occur on a daily basis, such as poverty or medical problems, are associated with increased depressive symptoms [1]. Not everyone exposed to stress has pathological consequences. The factors that protect against the “allostatic” load of repeated stress include: an ability to habituate to the stress, maintenance of hedonic tone and reward in the face of stress, and extinguishing of fearful memories [2]. It is clear from preclinical studies that CB1 receptor signalling increases sensitivity to reward [3] and is critical for the extinction of aversive memories [4]. Similarly, data is accumulating to support a role for the endocannabinoid system (ECS) in reducing stress responsivity, including a decrease in endocrine and behavioural responses to the initial presentation of the stress and in the development of habituation. Key Points