Cannabis use patterns, prevalence, and risk factors in Nigeria: a systematic review and meta-analysis

Reviews on cannabis use have been conducted in high-income countries, but limited data exist in Sub-Saharan Africa. In Nigeria, cannabis use is widespread, but systematic reviews summarizing the available data to generate robust evidence that can facilitate interventions have not been conducted. This systematic review and meta-analysis synthesized results from studies highlighting the patterns, prevalence, risk factors and motivations for cannabis use in Nigeria.

Databases searched include PubMed, Web of Science, Scopus, CINAHL, PsycINFO, ProQuest, African Journal Online (AJOL), and Google Scholar, for articles published in English between January 2000 and December 2023. Search terms were developed and slightly modified for each database. The primary outcomes were studies that examined the patterns, prevalence, risk factors, or motivation for cannabis use in Nigeria. The PECO framework guided the review, and all of the studies included were assessed for methodological rigor using the Joanna Briggs Institute checklist for prevalence studies.

The search yielded 1,911 research articles, which were screened, resulting in 72 studies being included in the review, with a total sample size of 45,968. Among adolescents, lifetime and past one-month prevalence of cannabis use were 3.90% (95% confidence interval (CI) = 1.99-7.51; I² = 97.6), and 2.34% [95% CI = 1.17-4.61; I² 96.1). Among adults, lifetime and past one-month prevalence of cannabis use were 8.28% (95% CI = 4.60-14.46; I² = 99.3) and 6.51% (95% CI = 3.48-11.87; I² = 97.2). Lifetime and one-month prevalence of cannabis use were 9.93% (95% CI = 4.36-21.08; I² = 99.6) and 3.56% (95% CI = 1.65-7.54; I² = 96.2) in the Northern region, and 5.59% (95% CI = 2.78-10.91; I² = 96.9) and 2.90% (95% CI = 1.27-6.47; I² = 97.2) in Western regions. Being a male was a risk factor for cannabis use and was mostly reported by studies of adults, and secondary school and university students. Cannabis was obtained from different sources, including peers, vendors and open markets.

Cannabis use prevalence is high in Nigeria, and several factors that may increase cannabis related harm are the motivating factors. The findings show the need for prevention programs targeting young people and treatment services for problematic users.