Prevalence and associated factors of cognitive impairment in patients with major depressive disorder: a cross-sectional study in Vietnam

Objective Cognitive impairment is increasingly recognised as a core feature of major depressive disorder (MDD), but data from low- and middle-income countries, including Vietnam, remain scarce. This study examined the prevalence of cognitive impairment among patients with MDD and identified associated factors.Method A cross-sectional study was conducted among 88 outpatients with MDD at the Mental Health Hospital of Ho Chi Minh City (December 2024–July 2025). Sociodemographic and clinical data were collected, cognitive function assessed with the Montreal Cognitive Assessment (MoCA), and logistic regression applied to examine associated factors.Results The mean MoCA score was 22.6 ± 4.2; 72.7% of participants had cognitive impairment. Verbal fluency, abstraction, and delayed recall were most affected, while orientation and attention were relatively preserved. Older age (OR = 1.1, 95% CI: 1.05–1.3, p = 0.003) and male sex (OR = 0.1, 95% CI: 0.03–0.8, p = 0.021) were significantly associated, while economic dependence showed a weak link (OR = 5.0, 95% CI: 1.01–24.7, p = 0.048).Conclusion Cognitive impairment is highly prevalent in MDD, especially in executive and memory domains. Older age and male sex were significant predictors, highlighting the need for routine cognitive screening in depression care.