Limited evidence for reduced learning rate adaptation in anxious-depression, before or after treatment

Prior research shows that humans adjust their learning rate based on environmental volatility. This adaptation may be reduced in individuals with high levels of anxious-depression, but past studies have been cross-sectional, making it unclear whether this adaptation is responsive to treatment. In the Precision in Psychiatry study, we examined changes in learning rate adaptation following four weeks of treatment in two patient groups receiving either internet-based cognitive behavioural therapy (iCBT; n=677) or antidepressants (n=95), compared to a group of healthy participants (n=95). All groups showed increased learning rates in volatile environments at baseline, but against our prediction, learning rate adaptation was not cross-sectionally associated with individual differences in anxious-depression. There was also no evidence that learning rate adaptation changed post-treatment, despite symptom improvements. However, in the antidepressant group, symptom reductions correlated with learning rate adaptation. This finding should be interpreted cautiously due to reliability concerns. Overall, our results suggest that associations between learning rate adaptation and anxious-depression are likely modest, may not be present in treatment-seeking adults, and do not improve following treatment.