Income, functional physical ability, and depressive symptoms in Ghana: a moderation analysis using national survey data

Depression remains a pressing public health concern globally, especially in low- and middle-income countries where mental health services are limited. While income disparities are widely associated with depressive symptoms, less is known about the potential moderating role of functional physical ability in this relationship. This study examines the interplay between household income, functional physical ability, and depressive symptoms among adults in Ghana, exploring whether the ability to perform physically demanding daily activities mitigates the psychological burden associated with low income. Using nationally representative data from Wave 3 of the Ghana Socioeconomic Panel Survey, an ordered probit regression model was employed to estimate the relationship between income and depressive symptoms, with functional physical ability included as a moderator. The analysis controlled for demographic, behavioural, and health-related variables. Both income and functional physical ability were independently associated with reduced depressive symptoms. Notably, functional physical ability significantly moderated the relationship between income and mental health, particularly among women. Among functionally able low-income individuals, the protective effect of income on depression was more pronounced, suggesting that functional physical ability can buffer against the negative mental health effects of income deprivation. The findings support the substitution theory, indicating that maintaining functional physical ability may be associated with resilience to depressive symptoms, especially in low-resource settings where physical capability is closely tied to the ability to work and meet daily needs.