Sammendrag
Background:Conflicting findings from individual epidemiological studies do not allow for valid
assumptions about the true prevalenceof dementia in sub-Saharan Africa (SSA). We conducted a
systematic review and meta-analysis of dementia studies in SSA to arrive at a pooled prevalence estimate and associated factors.
Materials and methods:We searched Medline, EMBASE, PsychINFO, and African Journals Online using
index medicus keywords for dementia and the .mp operator for all 54 SSA countries or regions. Further
information was retrieved through a manual search of references from relevant articles. We included peerreviewed original studies with epidemiological or experimental designs, conducted random effect metaanalysis of prevalence estimates and determined associated factors using the inverse of variance method.
Results:A total of 38 studies met criteria for syntheses. The pooled prevalence of clinically diagnosed
dementia derived from an overall sample of 6964 older community-dwellers was 4.0% (95% C.I=3.0%-
6.0%). We observed a pattern of distinctly low rates in West Africa (2.0%, 95% C.I=2.0%-3.0%)and
higher rates in East and Central Africa (6.0%, 95% C.I=5.0%-8.0%). Older age was the dominant factor
associated with prevalent dementia. This factor contributed 99.3% of the total variance of all
systematically associated factors. Most of the weight of association of older age and dementia was
provided by studies conducted in West Africa (the region with the lower estimated prevalence).
Conclusion:There are subsisting evidence gaps precluding robust estimation of age-adjusted prevalence
of dementia in SSA. Nevertheless, the findings from the present study provide useful information about
the possible mechanisms underlyingthe observed low prevalence of dementia in SSA and other
developing countries.
Keywords:Low and Middle income countries; sub-Saharan Africa; Dementia; prevalence; epidemiology;
pooled estimates
Résumé
Contexte: Les résultats contradictoires des études épidémiologiques individuelles ne permettent pas de
supposer valides sur la prévalence réelle de la démence en Afrique subsaharienne (ASS). Nous avons
effectué une revue systématique et une méta-analyse des études sur la démence en Afrique subsaharienne pour arriver à une estimation de la prévalence regroupée et des facteurs associés.
Matériel et méthodes: Nous avons effectué des recherches dans Medline, EMBASE, PsychINFO et
Journaux Africain En Ligne à l’aide d’index mots-clés Médicus pour la démence et l’opérateur mp pour
tous les 54 pays ou régions d’Afrique subsaharienne. De plus amples informations ont été obtenues grâce à une recherche manuelle des références des articles pertinents. Nous avons inclus des études originales évaluées par des pairs avec des plans épidémiologiques ou expérimentaux, effectué une méta-analyse àeffet aléatoire des estimations de la prévalence et déterminé les facteurs associés en utilisant la méthode de l’inverse de la variance.
Résultats: Au total, 38 études répondaient aux critères de synthèse. La prévalence groupée de démence
diagnostiquée cliniquement dérivée d’un échantillon total de 6964 d’habitants plus âgés de la
communauté était de 4,0% (IC à 95% = 3,0% à 6,0%). Nous avons observé un schéma de taux nettement
bas en Afrique de l’Ouest (2,0%, IC 95% = 2,0% -3,0%) et des taux plus élevés en Afrique de l’Est et
Centrale (6,0%, IC 95% = 5,0% -8,0%). L’âge avancé était le facteur dominant associé à la démence
prévalente. Ce facteur a contribué à 99,3% de la variance totale de tous les facteurs systématiquement
associés. La majeure partie de lacharge de l’association entre l’âge avancé et la démence a été fournie par des études menées en Afrique de l’Ouest (la région avec la prévalence estimée la plus faible).
Conclusion: Il existe des lacunes dans les preuves qui empêchent une estimation robuste de la prévalence de la démence ajustée selon l’âge en ASS. Néanmoins, les résultats de la présente étude fournissent des informations utiles sur les mécanismes possibles à l’origine de la faible prévalence observée de la démence en Afrique subsaharienne et dans d’autres pays en développement.
Mots-clés: Pays à revenu faible et intermédiaire ; Afrique Sub-Saharienne ; Démence; prévalence ;
épidémiologie; estimationsgroupées
Correspondence: Dr. A. Ojabemi, Department of Psychiatry, College of Medicine, Unversity of Ibadan, Ibadan, Nigeria. Email: drakinjagbemi@yahoo.com; akinojagbemi@gmail.com
Referanser
Jones J and Hunter D. Consensus methods for medical and health services research. Bmj. 1995;311(7001):376-80.
Ferri CP, Prince M, Brayne C, et al. Global prevalence of dementia: a Delphi consensus study. Lancet. 2005;366(9503):2112-7.
Hendrie HC, Ogunniyi A, Hall KS, et al. Incidence of dementia and Alzheimer disease in 2 communities: Yoruba residing in Ibadan, Nigeria, and African Americans residing in Indianapolis, Indiana. Jama. 2001;285(6):739-747.
Kalaria RN, Maestre GE, Arizaga R, et al. Alzheimer’s disease and vascular dementia in developing countries: prevalence, management, and risk factors. The Lancet Neurology. 2008;7(9):812-826.
Gureje O, Ogunniyi A, Kola L and Abiona T. Incidence of and risk factors for dementia in the Ibadan study of aging. Journal of the American Geriatrics Society. 2011;59(5):869-74.
National Institute for health and Care Excellence. The guidelines manual: process and method guide. London: National Institute for health and Care Excellence,; 2012.
Moher D, Liberati A, Tetzlaff J, Altman DG and Group P. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA Statement. Open medicine : a peer-reviewed, independent, open-access journal. 2009;3(3):e123-30.
Jackson R, Ameratunga S, Broad J, et al. The GATE frame: critical appraisal with pictures. Evid Based Med. 2006;11(2):35-38.
Habib AG, Yakasai AM, Owolabi LF, et al. Neurocognitive impairment in HIV-1-infected adults in Sub-Saharan Africa: a systematic review and meta-analysis. Int J Infect Dis. 2013;17(10):e820-31.
The Cochrane Collaboration. Review Manager (RevMan) [Computer program]. Version 5.3. ed. The Nordic Cochrane Centre, Copenhagen: The Cochrane Collaboration; 2014.
Toure K, Coumé M, Ndiaye Ndongo ND, et al. Risk Factors for Dementia in a Senegalese Elderly Population African Journal of Neurological Sciences 2009;28(1):1-15.
Mets TF. The disease pattern of elderly medical patients in Rwanda, central Africa. J Trop Med Hyg. 1993;96(5):291-300.
Lambo TA. Psychiatric disorders in the aged: epidemiology and preventive measures. West Afr Med J. 1966;15(3):121-124.
Ihezue UH and Okpara E. Psychiatric disorders of old age in Enugu, Nigeria. Sociodemographic and clinical characteristics. Acta psychiatrica Scandinavica. 1989;79(4):332-7.
Ogunniyi A, Lekwauwa UG, Falope ZF and Osuntokun BO. Clinically-diagnosed dementing illnesses in Ibadan: features, types and associated conditions. African journal of medicine and medical sciences. 1993;22(3):61-64.
Osuntokun BO, Ogunniyi A, Junaid TA and Lekwauwa UG. Autopsy survey for Alzheimer’s disease in Nigerian Africans: a preliminary report. African journal of medicine and medical sciences. 1995;24(1):75-79.
Ouango JG, Goumbri P, Karfo K, Nana B and Ouédraogo A. Socio-demographic, clinical and therapeutic characteristics of dementia in Burkina Faso. Neurologie Psychiatrie Geriatrie.14(81):163-168.
Siddiqi OK, Atadzhanov M, Birbeck GL and Koralnik IJ. The spectrum of neurological disorders in a Zambian tertiary care hospital. Journal of the neurological sciences. 2010;290(1-2):1-5.
Callixte KT, Clet TB, Jacques D, et al. The pattern of neurological diseases in elderly people in outpatient consultations in Sub-Saharan Africa. BMC Res Notes. 2015;8:159.
Napon C, Traore S, Idris S, et al. Dementias in sub-saharan Africa: clinical and etiological aspects in hospital environment in ouagadougou (Burkina Faso). African Journal of Neurological Sciences. 2009;28(1):unpaginated.
Baiyewu O, Adeyemi JD and Ogunniyi A. Psychiatric disorders in Nigerian nursing home residents. International journal of geriatric psychiatry. 1997;12(12):1146-1150.
Ogunniyi A, Hall KS, Gureje O, et al. Risk factors for incident Alzheimer’s disease in African Americans and Yoruba. Metab Brain Dis. 2006;21(2-3):235-40.
Paddick SM, Kisoli A, Dotchin CL, et al. Mortality rates in community-dwelling Tanzanians with dementia and mild cognitive impairment: a 4-year follow-up study. Age and ageing. 2015;44(4):636-641.
Ojagbemi A, Bello T and Gureje O. Cognitive Reserve, Incident Dementia, and Associated Mortality in the Ibadan Study of Ageing. J Am Geriatr Soc. 2016;64(3):590-595.
Hall K, Gureje O, Gao S, et al. Risk factors and Alzheimer’s disease: a comparative study of two communities. The Australian and New Zealand journal of psychiatry. 1998;32(5):698-706.
Ogunniyi A, Lane KA, Baiyewu O, et al. Hypertension and incident dementia in community-dwelling elderly Yoruba Nigerians. Acta neurologica Scandinavica. 2011;124(6):396-402.
Ogunniyi A, Gao S, Unverzagt FW, et al. Weight loss and incident dementia in elderly Yoruba Nigerians: a 10-year follow-up study. International psychogeriatrics / IPA. 2011;23(3):387-394.
Perkins AJ, Hui SL, Ogunniyi A, et al. Risk of mortality for dementia in a developing country: the Yoruba in Nigeria. International journal of geriatric psychiatry. 2002;17(6):566-573.
Samba H, Guerchet M, Ndamba-Bandzouzi B, et al. Dementia-associated mortality and its predictors among older adults in sub-Saharan Africa: results from a 2-year follow-up in Congo (the EPIDEMCA-FU study). Age and ageing. 2016;45(5):681-687.
American Psychiatric Association. Diagnostic and Statistical Manual of Mental disorders: 4th edition (DSM IV) text revision (ed). 4th edition. Text revision ed. Washington DC: American Psychiatric Association; 1994.
World Health Organisation. International Classification of Diseases: 10th revision (ICD 10). 10th Revision ed. Geneva: World Health Organisation; 1992.
Ochayi B and Thacher TD. Risk factors for dementia in central Nigeria. Aging & mental health. 2006;10(6):616-620.
Gureje O, Ogunniyi A and Kola L. The profile and impact of probable dementia in a sub-Saharan African community: Results from the Ibadan Study of Aging. Journal of psychosomatic research. 2006;61(3):327-333.
Paraiso MN, Guerchet M, Saizonou J, et al. Prevalence of dementia among elderly people living in Cotonou, an urban area of Benin (West Africa). Neuroepidemiology. 2011;36(4):245-51.
Longdon AR, Paddick SM, Kisoli A, et al. The prevalence of dementia in rural Tanzania: a cross-sectional community-based study. International journal of geriatric psychiatry. 2013;28(7):728-737.
Paddick SM, Longdon AR, Kisoli A, et al. Dementia prevalence estimates in sub-Saharan Africa: comparison of two diagnostic criteria. Glob Health Action. 2013;6(1):19646.
Guerchet M, Ndamba-Bandzouzi B, Mbelesso P, et al. Prevalence of dementia in two countries of Central Africa: comparison of rural and urban areas in the EPIDEMCA study. 29th International Conference of Alzheimer’s Disease International; May 1-4, 2014; San Juan, Puerto Rico2014.
Guerchet M, M’Belesso P, Mouanga AM, et al. Prevalence of dementia in elderly living in two cities of Central Africa: the EDAC survey. Dementia and geriatric cognitive disorders. 2010;30(3):261-268.
Mbelesso P, Tabo A, Guerchet M, et al. [Epidemiology of dementia in elderly living in the 3rd borough of Bangui (Central African Republic)]. Bull Soc Pathol Exot. 2012;105(5):388-395.
Ogunniyi A, Gureje O, Baiyewu O, et al. Profile of dementia in a Nigerian community—types, pattern of impairment, and severity rating. J Natl Med Assoc. 1997;89(6):392-396.
Guerchet M, Houinato D, Paraiso MN, et al. Cognitive impairment and dementia in elderly people living in rural Benin, west Africa. Dementia and geriatric cognitive disorders. 2009;27(1):34-41.
Yusuf AJ, Baiyewu O, Sheikh TL and Shehu AU. Prevalence of dementia and dementia subtypes among community-dwelling elderly people in northern Nigeria. International psychogeriatrics / IPA. 2011;23(3):379-386.
Guerchet M, Mouanga AM, M’Belesso P, et al. Factors associated with dementia among elderly people living in two cities in Central Africa: the EDAC multicenter study. Journal of Alzheimer’s disease : JAD. 2012;29(1):15-24.
De Rouvray C, Jesus P, Guerchet M, et al. The nutritional status of older people with and without dementia living in an urban setting in Central Africa: the EDAC study. J Nutr Health Aging. 2014;18(10):868-875.
Pilleron S, Jesus P, Desport JC, et al. Association between mild cognitive impairment and dementia and undernutrition among elderly people in Central Africa: some results from the EPIDEMCA (Epidemiology of Dementia in Central Africa) programme. Br J Nutr. 2015;114(2):306-315.
Kua EH and Ko SM. Prevalence of dementia among elderly Chinese and Malay residents of Singapore. International psychogeriatrics / IPA. 1995;7(3):439-446.
Rizzi L, Rosset I and Roriz-Cruz M. Global epidemiology of dementia: Alzheimer’s and vascular types. Biomed Res Int. 2014;2014:908915.
Nitrini R, Bottino CM, Albala C, et al. Prevalence of dementia in Latin America: a collaborative study of population-based cohorts. International psychogeriatrics / IPA. 2009;21(4):622-630.
Prince M, Acosta D, Chiu H, Scazufca M and Varghese M, Dementia Research G. Dementia diagnosis in developing countries: a cross-cultural validation study. Lancet. 2003;361(9361):909-917.
Prince M, Acosta D, Ferri CP, et al. Dementia incidence and mortality in middle-income countries, and associations with indicators of cognitive reserve: a 10/66 Dementia Research Group population-based cohort study. Lancet. 2012;380(9836):50-58.
Brayne C. The elephant in the room - healthy brains in later life, epidemiology and public health. Nature reviews Neuroscience. 2007;8(3):233-239.
Das SK, Biswas A, Roy T, et al. A random sample survey for prevalence of major neurological disorders in Kolkata. Indian J Med Res. 2006;124(2):163-172.
Velkoff VA and Kowal PR. Population aging in sub-Saharan Africa: Demo-graphic dimensions 2006. In: U.S. Census Bureau, ed. Current Population Reports. Washington, DC: U.S. Government Printing Office.; 2007.
Wang H, Dwyer-Lindgren L, Lofgren KT, et al. Age-specific and sex-specific mortality in 187 countries, 1970-2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet. 2012;380(9859):2071-2094.
Ojagbemi A, Bello T, Luo Z and Gureje O. Living Conditions, Low Socioeconomic Position, and Mortality in the Ibadan Study of Aging. The journals of gerontology Series B, Psychological sciences and social sciences. 2016.
Country Statistics [Internet]. 2008 [cited December 15th, 2014]. Available from: www.unicef.org/infobycountry/niger_statistics
Gureje O, Ogunniyi A, Kola L and Afolabi E. Functional disability in elderly Nigerians: Results from the Ibadan Study of Aging. Journal of the American Geriatrics Society. 2006;54(11):1784-1789.
World Health Organisation. The World Health Report 2008: primary health care- now or never. Geneva: World Health Organisation; 2008.
Gureje O, Nortje G, Makanjuola V, et al. The role of global traditional and complementary systems of medicine in the treatment of mental health disorders. Lancet Psychiatry. 2015;2(2):168-177.
Ojagbemi A and Daley S. Implementing the Dementia Carers Support Initiative of the National Institute for Health and Care Excellence in a sub-Saharan African Setting. J Health Care Poor Underserved. 2015;26(4):1368-1376.