Prevalence of dementia in Nigeria: a systematic review of the evidence.

ABSTRACT

BACKGROUND: The burden of dementia is poorly understood in Nigeria. We sought to gather available epidemiologic evidence on dementia in Nigeria to provide country-wide estimates of its prevalence and associated risks. METHODS: We searched MEDLINE, EMBASE, Global Health, Africa Journals Online (AJOL) and Google Scholar for epidemiologic studies on dementia in Nigeria from 1990 to 2018. We pooled crude estimates using random effects meta-analysis. A meta-regression epidemiologic model, using the United Nations demographics for Nigeria, was used to estimate the absolute number of people living with dementia in Nigeria in 1995 and 2015. RESULTS: Our searches returned 835 studies, of which nine were selected. These included 10 820 individuals with a median age of 74.4 years. Heterogeneity (I 2 =98.8%, P<0.001) was high across studies. Five studies were conducted in the South-west, and four studies were rated as high quality. The pooled crude prevalence of dementia in Nigeria was 4.9% (95% CI 3.0-6.9) with prevalence significantly higher in women (6.7%, 3.6-9.9) compared to men (3.1%, 1.2-5.0). Age 80+ (odds ratio (OR) 1.6, 1.3-1.9), female sex (OR 2.2, 1.4-3.4) and BMI ≤18.5 (OR 3.5, 1.2-10.1) were significant risks for dementia in Nigeria. Using our epidemiologic model, we estimated that the number of dementia cases increased by over 400% over a 20-year period, increasing from 63 512 in 1995 to 318 011 in 2015 among persons aged ≥60 years. CONCLUSION: Our findings suggest the prevalence and cases of dementia have increased in Nigeria over the last two decades. Population-wide response to dementia is lacking.