Treating depression predicts cognitive improvement in Mild Cognitive Impairment: a 1-year prospective cohort study

Background: Depression frequently coexists with Mild Cognitive Impairment (MCI) and may influence its clinical trajectory, but the effect of treating depression on cognitive outcomes remains unclear. Objective: To evaluate whether treating depression is associated with distinct cognitive trajectories. Methods: This prospective cohort included 290 outpatients with MCI (139 with comorbid major depressive disorder, MCI + MDD; 151 without depression, MCI-only). Global cognition (Mini-Mental State Examination [MMSE], Montreal Cognitive Assessment [MoCA]) and depressive symptoms (GDS-15) were assessed at baseline and 12-month follow-up. Results: At baseline, MCI + MDD patients scored lower on both MMSE (27.3 vs 28.0, p < .01) and MoCA (20.6 vs 22.5, p < .01). Over 12 months, MCI + MDD patients improved (MMSE + 0.7; MoCA + 1.3) while MCI-only patients declined (MMSE -0.9; MoCA -1.1), a significant between-group difference for both MMSE (+1.55, d = 0.89) and MoCA (+2.42, d = 0.82). GDS scores fell in the MCI + MDD group (Δ -1.45; p < .01). After adjusting for baseline scores, between-group differences at follow-up remained significant for both MMSE (+1.20, p < .001) and MoCA (+1.43, p < .001). At 12 months, 14.4% of MCI+MDD patients no longer met MCI criteria versus 2.6% of MCI-only patients (p < .001). Conclusions: Systematic detection and management of depression in memory clinics may help mitigate cognitive decline and should be integrated into routine care.