Temporal cortical gray matter volume relates to symptom improvement during cognitive behavioral therapy for depression

Cognitive behavioral therapy (CBT) is a first-line treatment for depression, yet treatment responses vary considerably. Understanding neurobiological factors associated with symptom improvement may help elucidate mechanisms underlying therapeutic change. This study investigated whether baseline cortical gray matter volume (GMV) is associated with reductions in depressive symptom severity during CBT. Therefore, n = 52 patients with unipolar affective disorders and at least mild depressive symptoms (according to BDI-II) and n = 42 healthy controls underwent clinical assessments and structural MRI at baseline; depressive symptom severity was reassessed after six months of outpatient CBT. Multiple regression analyses examined associations between pre-treatment cortical GMV and reductions in depressive symptoms under false discovery rate (FDR) correction. Additional models included anxiety, perceived stress, and childhood trauma as predictors. Compared to controls, patients exhibited significantly higher depressive symptom severity at baseline and greater symptom reduction over time (all p < 0.001). Within patients, baseline GMV of the right middle temporal gyrus (MTG) was significantly associated with symptom reduction (baseline-follow-up; β = 0.55, p_FDR = 0.033). Right MTG volume accounted for additional variance in symptom reduction beyond established clinical variables (ΔR² = 0.15). Group differences in GMV did not remain significant following FDR correction. These findings suggest that temporal gyrus GMV is associated with symptom improvement following CBT in unipolar depression, extending the focus beyond traditionally emphasized limbic regions. Preserved temporal morphology may support cognitive and emotional processes engaged during CBT, underscoring the relevance of temporal cortical structure for understanding the neurobiological correlates of psychotherapy response.