Individual differences in fear extinction learning and the endocannabinoid system

Abstract

Anxiety, trauma and stressor-related disorders are the most common mental disorders in the world. The likelihood of developing these disorders is higher in occupations where there is an increased likelihood of exposure to stressful and traumatic situations, such as in the military. More insight into the development and treatment of these disorders is of great importance because current psychological and pharmacological treatments are insufficient for 40% of patients. This thesis investigates two important systems that can provide more insight into the development and treatment of anxiety, trauma and stressor-related disorders. First, individual differences in fear learning and the use of these differences in association with treatment outcome. Second, the role of the endocannabinoid system in these disorders. The studies in this thesis show that different fear learning classes can be distinguished using a fear conditioning task. The classes of ‘generalizing’ and ‘poor fear extinction’ were found but were not associated with treatment outcome. In the second part, it was found that compounds that enhances the endocannabinoid system may alleviate anxiety symptoms. There was also evidence of associations between endogenous cannabinoid and anxiety symptoms. This research contributes to translating more fundamental research into applicability in clinical practice in the development and treatment of anxiety, trauma and stressor-related disorders. This may contribute to the prevention and better treatment of these disorders.