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.