Fear less : Individual differences in fear conditioning and their relation to treatment outcome in anxiety disorders

Findings from animal and human experimental studies highlight the importance of fear conditioning processes in the development and treatment of anxiety disorders. The work reported in this thesis was focused on potential abnormalities in the acquisition and extinction of fear in patients with anxiety disorders, and on exploring the predictive value of individual differences in fear extinction on treatment outcome. In this thesis, differences in the acquisition and extinction of fear between patients with anxiety disorders and healthy comparison subjects have been investigated at group level in multiple studies. The results from these studies demonstrated increased acquisition of fear and decreased extinction of fear in patients with anxiety disorders relative to comparison subjects. These abnormalities in fear conditioning seem to occur across various anxiety disorder diagnoses. However, when studying individual differences in fear conditioning, only a minority of patients with anxiety disorders are characterized by increased fear acquisition and decreased fear extinction. These findings suggest that mechanisms other than fear conditioning (for example, personality factors or cognitive functions) may be involved in the development of anxiety disorders as well. The predictive value of individual differences in fear extinction on treatment outcome was also studied in this thesis, because extinction processes are thought to -at least in part- underlie the beneficial effects of therapy. Results from this thesis support this assumption, since we demonstrated that individual trajectories of fear conditioning predict treatment outcome in patients with anxiety disorders. The current findings imply that individual differences in fear acquisition and extinction partly explain why some patients benefit from therapy and others do not. In addition, more personalized treatment may be developed, based on individual differences in fear conditioning.