Dementia and Depression in Africa Olusegun Baiyewu

INTRODUCTION

In 2001 it was projected that about 7% of Africans would be aged 60 years and over in the year 2002¹. Although the emphasis of health care in Africa is on preventable and communicable diseases in children and nursing mothers, as over 50% of the population is under 18 years of age, it has been estimated that the number of people aged 60 years and older in Africa will increase over the next few years. It thus becomes increasingly important that chronic illnesses associated with old age are considered. In this category are dementia and depression. In the last decade, a few studies have been carried out in Africa on dementia and depression; although the quantity of research on older person is small, significant advancements have been made.

Depression

One of the earliest community surveys on depression in the elderly in Africa was the study by Ben-Arie et al.², but since the 1990s there have been a number of research reports on old age depression in Africa^3–6. These studies were done in various locations, rural, urban and a combination of both and the prevalence rates varied depending on the methodology. For example, studies in which screening questionnaires alone are used tend to have higher rates, in the range of 20%, while those that have second-stage clinical diagnosis have rates ranging from 5 to 8%. A theme that emerges in all studies is that populations with high levels of depression correlate with low levels of education and low income.

Some hospital-based studies have looked at depression and other psychiatric disorders in clinic attendees⁷, and in patients admitted to non-psychiatric facilities^8,9. In these groups, high level of medical co-morbidity is a regular finding, though relationship between medical co-morbidity and depression is not often established. Another issue is that depression is often not recognized and neither is it treated⁵. Interaction between depression and chronic medical illnesses, such as heart failure, stroke and cancer, need further research. Intervention and outcome studies are also lacking.

Dementia

The flagship of dementia research in Africa is the Indianapolis–Ibadan Dementia Research Project, which has been ongoing since 1992. This group has reported prevalence and incidence rates for dementia and Alzheimer’s disease in Ibadan and Indianapolis and found that rates for both conditions were lower in Ibadan elders than in African Americans in Indianapolis^10,11. One important issue in assessment of cognitive functioning is that many questionnaires used in Western countries need modification when used in developing countries as the elders often have low education levels and have been involved in low occupational pursuits all their life. For example the Mini Mental State Examination (MMSE)¹² has both a ceiling and a floor effect due to education. In contrast, a screening questionnaire like the Community Screening Interview for Dementia (CSI–D’)¹³ has little education or culture effect and has been used in disparate populations. Another questionnaire developed by the group is Stick Design¹⁴, which resolves the graphomotor function difficulties experienced by people with little education when asked to carry out a constructional praxis test.

In this group of studies risk factors for poor cognitive functioning identified include age and female gender, but the most important risk factor for Alzheimer’s disease, apolipoprotein E4, is not related to either dementia or Alzheimer’s disease in Nigerians^15,16. A similar report from East Africa also found that ApoE4 is not related to Alzheimer’s disease¹⁷.

A study from Egypt, however, reported a prevalence of 4.5% based on DSM-IV diagnosis¹⁸. This is close to the 5% often reported in Euro-American studies.

A study of mortality in the Indianapolis–Ibadan group showed increased mortality in Ibadan generally and a higher though non-significant rate in demented subjects when the two sites were compared¹⁹

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