biostudies-literatureUnknown55(6)Oginni OAAcademy of Medical SciencesWelsh Clinical Academic Track FellowshipGlobally, most children and adolescents live in low- and middle-income (LAMI) countries. Despite the high and under-recognized mental health burden in these settings, there is little systematic research to inform cost-effective mental health interventions. Identifying causal risk and protective mechanisms is important to inform such interventions. Longitudinal genetically informative designs can help identify potentially causal environmental mechanisms in the etiology of childhood psychopathology but few have been carried out in LAMI settings. We tested the feasibility of a twin-family study in a semi-urban setting in South-Western Nigeria. We recruited 320 family units, each comprising at least one parent and both twins aged 2.5-5.9 (x̄ = 4.0 ± 0.92) years from two towns using five strateBehavior genetics438-453https://www.ebi.ac.uk/biostudies/studies/S-EPMC12719352biostudies-literatureChild Mental Health Research in Low- and Middle-Income Countries: A Twin-Family Feasibility Study in Nigeria.PMC12719352Oguns OJeje OMapayi BRijsdijk FOginni OAStein DJGilbert ROlorumoteni OThapar AfalseChild Mental Health Research in Low- and Middle-Income Countries: A Twin-Family Feasibility Study in Nigeria.Globally, most children and adolescents live in low- and middle-income (LAMI) countries. Despite the high and under-recognized mental health burden in these settings, there is little systematic research to inform cost-effective mental health interventions. Identifying causal risk and protective mechanisms is important to inform such interventions. Longitudinal genetically informative designs can help identify potentially causal environmental mechanisms in the etiology of childhood psychopathology but few have been carried out in LAMI settings. We tested the feasibility of a twin-family study in a semi-urban setting in South-Western Nigeria. We recruited 320 family units, each comprising at least one parent and both twins aged 2.5-5.9 (x̄ = 4.0 ± 0.92) years from two towns using five strate2025-01-01T00:00:00Z2025 Nov2026-06-08T05:30:57.655Z2026-06-08T03:08:38.799ZS-EPMC127193524107761310.1007/s10519-025-10235-z