Patterns, Risk and Protective Factors of Substance Use among Adolescents in South-West Nigeria: A Systematic Review

Abstract

Background: Substance use among adolescents is an escalating public-health problem in Nigeria with implications for mental health, injury and social dysfunction. We synthesised evidence from studies conducted in South-West Nigerian states to describe substance-use patterns, identify risk and protective factors, and appraise methodological quality to inform prevention and research priorities.

Methods: We conducted a systematic review of original, open-access quantitative studies published 2007 to 2024. Searches of Web of Science, PubMed, Google Scholar and EBSCOhost were performed; reference lists were hand searched. Eligible studies reported prevalence, patterns or determinants of substance use among adolescents or youth in South-West Nigeria; alcohol-only studies, reviews, and case reports. Study quality was appraised using the Joanna Briggs Institute (JBI) checklist for cross-sectional studies. Due to heterogeneity of populations, outcome definitions and measurement, we present a structured narrative synthesis. (PRISMA guidance followed.)

Results: Database searches identified 66 records; after deduplication, 55 records were screened. After full-text assessment (n = 28), eight studies were included. The eight studies (seven cross-sectional; one pilot) examined secondary-school and tertiary-level populations, a clinical sample, and community youth; sample sizes ranged from 249 to 11,799. Reported substance use prevalence varied (range across study reports), with overall high proportions in several samples (where reported: 40%–78% in some student samples). Commonly reported substances included alcohol/over-the-counter medicines, tobacco, tramadol (and other opioids), cannabis, amphetamines, inhalants and low-prevalence heroin/cocaine. Recurrent risk factors were male sex, older adolescent age, peer substance use/peer pressure, parental substance use/low parental monitoring, school disengagement/academic stress, mental-health symptoms (depression, anxiety), curiosity/experimentation and community availability. Protective factors included religiosity, parental guidance and monitoring, school-based positive behavioural programmes, and supply-reduction policies. Using the JBI checklist, most studies were rated low-to-moderate quality because of non-probability sampling, inconsistent outcome measurement (ever vs past-year vs current use), and limited control for confounding.

Conclusions: Substance use among adolescents in South-West Nigeria is prevalent across multiple substances and shaped by interlocking individual, family, peer and community factors. To inform prevention, surveillance must adopt standardised measures and representative sampling; longitudinal and intervention studies are needed. Family- and school-centred prevention and community supply-reduction efforts are priority actions.