Patients with major depressive disorder and PTSD have shown evidence of reward system dysfunction in fmRI studies, with reduced striatal activation during the performance of reward-related tasks89–91. Altered activation of reward circuits in depressed adolescents was associated with self-reports of reduced positive affect in naturalistic settings92. Differential reward system function has also been demonstrated in children of depressed versus never-depressed parents93. Of note, there is evidence that inter-individual variability in neural responses to reward anticipation in healthy individuals is associated with the Val158met COMT polymorphism55.
