Dementia in Africa: Current evidence, knowledge gaps, and future directions

Abstract

In tandem with the ever-increasing aging population in low and middle-income countries, the burden of dementia is rising on the African continent. Dementia prevalence varies from 2.3% to 20.0% and incidence rates are 13.3 per 1000 person-years with increasing mortality in parts of rapidly transforming Africa. Differences in nutrition, cardiovascular factors, comorbidities, infections, mortality, and detection likely contribute to lower incidence. Alzheimer's disease, vascular dementia, and human immunodeficiency virus/acquired immunodeficiency syndrome-associated neurocognitive disorders are the most common dementia subtypes. Comprehensive longitudinal studies with robust methodology and regional coverage would provide more reliable information. The apolipoprotein E (APOE) ε4 allele is most studied but has shown differential effects within African ancestry compared to Caucasian. More candidate gene and genome-wide association studies are needed to relate to dementia phenotypes. Validated culture-sensitive cognitive tools not influenced by education and language differences are critically needed for implementation across multidisciplinary groupings such as the proposed African Dementia Consortium.

Keywords: Africa; Alzheimer's disease; consortium; dementia; epidemiology; genetics; neuropathology. biomarkers; precision medicine; vascular dementia.

Figure 1:. Dementia in Africa and Dementia Care and Support Organisations

Map of Africa showing limited number of countries where incidence and prevalence studies have been conducted over the past 30 years. Some countries have reported isolated reports on dementia cases in particular Alzheimer’s disease or vascular dementia. Limited number of countries in which candidate gene investigations have been carried out. In several African countries dementia care and support organisations exist. Most of these are member organisations of ADI (https://www.alzint.org). Further reports of cases and deaths due to dementia in African countries are known (www.afro.who.int) but are not published in peer-reviewed sources.

Figure 2:. Prevalence of Dementia in Africa

Heat map showing wide range of dementia prevalence in African countries determined over the past 25 years. Dementia prevalence studies have also been conducted in Senegal and Kenya but the data are not published yet.