Academic journal article Bulletin of the World Health Organization

Prevalences of Dementia and Cognitive Impairment among Older People in Sub-Saharan Africa: A Systematic Review/ Prevalence De la Demence et Des Troubles Cognitifs Chez Les Personnes Agees En Afrique Sub-Saharienne: Une Etude Systematique/ la Prevalencia De la Demencia Y El Deterioro Cognitivo En Las Personas Mayores En El Africa Subsahariana: Una Revision Sistematica

Academic journal article Bulletin of the World Health Organization

Prevalences of Dementia and Cognitive Impairment among Older People in Sub-Saharan Africa: A Systematic Review/ Prevalence De la Demence et Des Troubles Cognitifs Chez Les Personnes Agees En Afrique Sub-Saharienne: Une Etude Systematique/ la Prevalencia De la Demencia Y El Deterioro Cognitivo En Las Personas Mayores En El Africa Subsahariana: Una Revision Sistematica

Article excerpt

Introduction

The prevalence of age-related health problems is becoming an important public health concern as proportions of older individuals in populations worldwide grow. (1) Dementia is one of the major causes of disability in older people. (2) It is a complex syndrome characterized by global and irreversible cognitive decline that is severe enough to undermine daily functioning. (3) Dementia is a chronic illness that arises from an interplay of genetic, environmental and behavioural factors, with severe adverse influences on social and physical activities and quality of life. In cognitive impairment and mild cognitive impairment, the cognitive deficit is less severe than in dementia and normal daily function and independence are generally maintained. It is a chronic condition that is a precursor to dementia in up to one third of cases. (3)

Cognitive impairment and dementia are increasing globally and are predicted to increase proportionately more in developing regions. (1,4-6) Projections indicate that by 2050 the number of individuals older than 60 years will be approximately 2 billion and will account for 22% of the world's population. Four fifths of the people older than 60 years will be living in developing countries in Africa, Asia or Latin America. (7) It is estimated that 35.6 million people are currently living with dementia worldwide and that the number will nearly double every 20 years, reaching 115.4 million in 2050, with the majority living in developing countries. (8) Of the total number of people with dementia worldwide, 57.7% lived in developing countries in 2010 and a proportionate increase to 70.5% by 2050 is anticipated. (8) Consequently, the health and social burden of cognitive impairment and dementia will rise dramatically in these regions. (9) Developing countries, including those in sub-Saharan Africa, are currently undergoing a demographic and epidemiological transition and the impact of population ageing in sub-Saharan Africa will increasingly augment the burden of noncommunicable and degenerative diseases in this region.

Few studies to determine the prevalence of dementia have been conducted in sub-Saharan Africa. (10,11) Early studies (12) showed a lower prevalence than in Europe (11,13) and the United States of America, where approximately 6.2% and 8%, respectively, of people aged 65 years or older are reported to have dementia. (14-16) The aim of this study was to perform a systematic review of the literature to obtain the best available estimates of the prevalences of cognitive impairment and dementia in sub-Saharan Africa and to identify gaps in current research.

Methods

A systematic review of studies reporting the prevalences of dementia and cognitive impairment among older black Africans in sub-Saharan Africa countries was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. (17)

Search strategy

We searched the following databases between February and May 2011: PubMed (search range, 1950 to week 18 of 2011); the Web of Knowledge, which includes the Web of Science Conference Proceedings Citation Index (1970 to week 18 of 20il), the BIOSIS Citation Index (1969 to week 18 of 2011), Journal Citation Reports (1997-2008) and CAB Abstracts (1973 to week 18 of 2011); EMBASE (1947 to week 18 of 011); ASSIA (1987 to week 18 of 2011) and PsycNET (1894 to week 18 of 2011). The search terms used included variations across the following broad terms: epidemiology, prevalence, incidence, cognition, cognitive impairment, dementia, Alzheimer disease, sub-Saharan Africa, names of individual sub-Saharan African countries, elderly and older people. Searches incorporated MeSH (medical subject heading) terms or equivalents, exploded terms and text word terms (Appendix A, available at: http://www2.warwick.ac.uk/fac/med/research/hscience/research/dementia/). We checked the reference lists of retrieved articles for further relevant studies. …

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