Why are girls more distressed than boys? A multi-domain framework applied to longitudinal data across four countries

Background: Girls are more likely than boys to experience psychological distress during adolescence. Drivers of this gender gap remain under-studied, despite its large impact on later life and outcomes, especially for women. Explanatory factors can be gendered in their prevalence (differential exposure) and/or in their impact (differential susceptibility). We developed a multi-domain framework of explanatory factors for distress and applied it in four low- and middle-income countries. Methods: We first proposed a framework of explanatory factors for psychological distress grouped into seven domains (biological, cognitive, psychological, behavioural, social, environmental and broader societal). We applied this framework to identify explanatory variables assessed in childhood and adolescence in the Young Lives longitudinal cohort studies in Ethiopia (N=908), India (N=952), Peru (N=634) and Vietnam (N=887). Distress symptoms at 18-19 years were measured with the Strengths and Difficulties Questionnaire Emotional Symptoms scale. Gendered prevalence of each explanatory factor was tested with Mann-Whitney tests, and gendered impact with country-specific linear regressions including a gender-by-factor interaction term. Exploratory boosted-tree machine-learning models, interpreted with SHAP values and permutation feature importance, examined the contribution of these factors to the gender gap in each country. Results: Distress was higher in girls than boys in every country, the gap ranging from 0.62 points in Ethiopia and Vietnam to 1.76 in India and 2.45 in Peru. Some explanatory factors were consistently gendered in prevalence (e.g. girls experienced greater role overload in each country), while others were gendered only in some countries (e.g. study amount was higher for girls in Peru and Vietnam, but not Ethiopia or India). Gendered impacts on distress displayed more variability across countries. For example, higher self-esteem was more protective for boys than girls in India, Peru and Vietnam, but more protective for girls in Ethiopia. The machine-learning models identified important predictors across all framework domains, though their salience varied by country. Conclusions: Our findings underscore the importance of considering multi-domain explanations for mental-health outcomes and observed inequalities in mental health. Large cross-country differences in the gender gap and in the prevalence and influence of explanatory factors caution against generalising drivers of mental-health outcomes and inequalities across contexts.