Mortality and dementia: what about older adults living in sub-Saharan Africa?

Maëlenn Guerchet is a researcher at King’s College London, Institute of Psychiatry, Psychology and Neuroscience, UK and the Inserm U1094 Tropical Neuroepidemiology unit, University of Limoges, France @IENTofficiel, with a major research focus on the epidemiology of dementia in low and middle income countries, especially in sub-Saharan Africa. Her paper Dementia-associated mortality and its predictors among older adults in sub-Saharan Africa: results from a two-year follow-up in Congo was recently published in Age and Ageing. She tweets at @mmguerchet

africa (1)Dementia has been recognised as a global challenge for the 21st century.  At the same time, the African population is ageing at an unprecedented rate. In 2015, over 58% of all people with dementia were living in low and middle countries (also referred as developing countries), of whom 4.03 million were living in Africa. The 2015 World Alzheimer Report highlighted increasing evidence on dementia prevalence in sub-Saharan Africa. Unfortunately, despite the magnitude of the situation, awareness about dementia remains low within the population and older people are rarely the target of specific health policies.

Over the last 10 years, the Institute of Tropical Neurology and Neuroepidemiology in Limoges and their collaborators in sub-Saharan Africa worked to fill in the gaps in the evidence. Studies were carried out in 3 Francophone countries exploring the epidemiology, knowledge and understanding around dementia. Their latest programme EPIDEMCA, Epidemiology of Dementia in Central Africa (Guerchet et al., 2014), included more than a thousand participants aged over 65 years living in the Republic of Congo: Brazzaville (the capital) and Gamboma (a rural area). Building on this baseline survey, these older adults were followed-up for two years (2012-2014), re-contacting and examining people to diagnose new cases of dementia every year (EPIDEMCA-FU study).

Globally, longitudinal studies suggest that dementia is associated with increased mortality risk among older people. Very little is known about how dementia affects mortality among older people living in sub-Saharan Africa yet. Dementia-related mortality was only documented in Nigeria and Tanzania, where a 3- to 6-fold higher mortality risk for people with dementia was found after five and four years respectively.

In our study, after only two years of follow-up, 101 (9.8%) participants were deceased: 34.9% of those who had dementia, 12.5% of those who had Mild Cognitive Impairment and 9.6% of those who had shown no sign of cognitive impairment at baseline. Compared with the latter group, people with dementia were 2.5 times more likely to die after 2 years. Among people with dementia, disease severity was strongly associated with increased mortality risk while across the full cohort, older people, males and those living in an urban area had an increased mortality risk.

Our results are consistent with the previous reports from sub-Saharan Africa and also highlight a high mortality in this population. In Congo, the lack of structured health care and of financial resources often limits access to healthcare for this population with increasing needs. This could possibly be contributing to a higher mortality among people with dementia. Our results underline the need for targeted health policies for older people and strategies for dementia care in sub-Saharan Africa.

In the context of an on-going epidemiologic and demographic transition on the African continent, now more than ever, the need is evident for new studies to estimate dementia prevalence, incidence, mortality and to monitor their changes over time.

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