The epidemiology of dementia in Africa: a review

Abstract

Very few of the 100 studies of the prevalence of dementia have been carried out in Africa. Much of the early work concerned small hospitalised samples. However, a series of studies from Ibadan, Nigeria, have produced consistently low rates for dementia, especially for Alzheimer's Disease. The most recent studies reveal rather higher rates, but still lower than surveys carried out elsewhere. The possible reasons for these findings are considered: differential survival rates, the hiding of cases by relatives because of stigma, reluctance to seek medical assistance as inappropriate, poor access to medical care, the feeling that the old person has come to the end of his useful life and defective case-finding techniques. The need for further research is emphasised.

Introduction

The number of elderly people in Africa is increasing very rapidly. In Kenya and Zimbabwe, for example, the number of people aged 55 and over is expected to treble between 1988 and 2020. Official figures from the UN project life expectancy in Africa to increase from under 40 yr in 1950 to almost 60 in 2010. However, fertility rates continue to rise, so that over-65s will remain only a tiny proportion of the total population until well into the next millennium.

One of the major health problems associated with increasing numbers of elderly people is to create is a comparable increase in the number of sufferers from Alzheimer's Disease and other forms of dementia. Dementia is strongly related to old age, with numbers doubling with every 5 years of age (Jorm, 1990, Henderson, 1994) and at present there is no cure.

Over 100 studies of prevalence have been carried out; almost every part of the world has been surveyed (Ineichen, 1998b). Very few surveys have taken place in developing countries, despite the fact that by 2025, an estimated 68% of the world's elderly will be living in them (Chandra et al., 1994). Even in the developing country studied most thoroughly, China, nearly all the work has been done in cities (Ineichen, 1996).

Most surveys reveal relatively similar rates, given that fieldwork variables are seldom precisely comparable. Relatively few epidemiological studies of mental illness in Africa have centred on dementia, or indeed on more general psychogeriatric problems. However, most report low rates.