Neural mechanisms of adolescent fear extinction and fear extinction during reconsolidation: a literature review

Abstract

Anxiety disorders and phobias are a growing problem in today’s society. Currently, anxiety is often treated using therapies that rely on the principles of fear extinction, in which patients are exposed to the feared stimulus without the feared outcome, enabling them to re-interpret the feared stimulus as safe. However, relapse for fear extinction is high. Moreover, anxiety peaks during adolescence, a period in which extinction retention has been shown to be especially impaired. Recently, a new paradigm has been brought forward that relies on bringing the fear memory into a labile state and then modifying it using extinction training. This paradigm has shown positive results compared to extinction alone in both adults and adolescents. However, the development of the neural mechanisms of extinction alone and during memory reconsolidation is as of yet unclear, and is reviewed here. The literature suggests that extinction retention may be impaired in adolescents, because of the relatively delayed development of the ventromedial prefrontal cortex during adolescence, a region involved in the inhibition of the fear memory in favor of the extinction memory, as compared to subcortical regions such as the amygdala. In contrast, extinction during memory reconsolidation may involve directly modifying the fear memory in the lateral amygdala, requiring significantly less to no inhibition from prefrontal regions. The results suggest that the memory reconsolidation paradigm may be beneficial for use in both adults and adolescents. However, more research investigating the neural mechanisms of memory reconsolidation is needed. Moreover, the boundary conditions of the memory reconsolidation paradigm need further investigation in adolescence. For example, the circumstances under which memories of adolescents are destabilized are as of yet unknown.