Local and network neural activations and their associations with sleep parameters during threat conditioning and extinction in persons with Generalized Anxiety Disorder with and without Insomnia Disorder
Deficient extinction learning and memory are hypothesized mechanisms for pathological anxiety that are associated with sleep disturbance. fMRI neural activations to threat conditioning, extinction learning, and extinction recall were measured. Activations were compared, in persons with Generalized Anxiety Disorder (GAD), between those with moderate to severe Insomnia Disorder (ID) and those with absent or sub-threshold ID. Relationships of activations with measures of sleep quality and physiology were examined. Between-group comparisons and whole-sample correlation with sleep parameters were examined in relation to large-scale brain networks using a liberal cluster-determining threshold. Localized activations were then identified using family-wise error correction. Activations to the reinforced stimulus (CS+) that increased from the beginning to end ("across") threat conditioning were more extensive within the GAD+ID group. Increased activations to the CS+ across extinction learning were greater within the GAD-ID than the GAD+ID group, and delayed 24h in the latter. Greater sleep efficiency was associated with decreased activations across threat conditioning, but with increased activations across extinction learning. Better sleep quality promoted greater engagement of neural substrates of extinction learning. The GAD+ID group failed to engage brain areas supporting extinction learning immediately following threat conditioning, but did so when stimuli were again presented following a delay. HighlightsGeneralized Anxiety Disorder subjects with moderate/severe vs absent/mild insomnia compared Neural responses to threat conditioning, extinction learning/memory analyzed and sleep recorded Low and high thresholds identified large-scale networks and localized activations respectively Threat and regulatory activations at extinction learning in mild insomnia delayed when more severe Better sleep quality predicted greater activation of regulatory areas during extinction learning