The research was led by the 10/66 Dementia Research Group based at the Institute of Psychiatry at King’s College London and published today in PLoS Medicine.
MCI is an intermediate state between normal signs of cognitive aging, such as becoming increasingly forgetful, and dementia, and may be linked to an increased risk of dementia,
The research group interviewed roughly 15,000 people aged over 65 years who did not have dementia in eight low and middle incomes countries—Cuba, Dominican Republic, Peru, Mexico, Venezuela, Puerto Rico, China, and India.
Their mental and physical health, cognitive function were also assessed and their relatives and carers interviewed for further details about any memory loss, any other decline in cognitive function or the presence of any neuropsychiatric symptoms.
The prevalence of MCI ranged quite widely, from 0.8% in China to 4.3% in India. They found that age or level of former education did not seem to be linked to MCI and that men had a slightly higher prevalence of MCI than women. The authors found that MCI was associated with disability, anxiety, apathy and irritability but not with depression.
Dr Robert Stewart, senior author of the paper at the IoP at King’s says: ‘By 2050, it’s estimated that more than 115 million people will have dementia, and much of the expected increase will occur in low and middle income countries where the population is rapidly ageing.
‘I hope that the information on MCI in low and middle income countries we report in this study could help inform health care and social service planning in these rapidly ageing and highly populated regions of the world.’
The authors added that more long-term studies are needed to investigate whether MCI can be used as a reliable marker for further cognitive decline and dementia, and into the associations with disability and neuropsychiatric symptoms.
Dr Stewart adds: ‘It is also worth considering whether cultural influences may impact upon the identification of MCI – it may be that people in certain countries may be more or less likely to admit to memory difficulties. Whilst this may help in part explain the variation between countries, the association between MCI and disability remained constant throughout.’
The 10/66 Dementia Research Group is supported by the Wellcome Trust (UK), the World Health Organization, the US Alzheimer’s Association and the Fondo Nacional de Ciencia Y Tecnologia, Consejo de Desarrollo Cientifico Y Humanistico, Universidad Central de Venezuela (Venezuela). The lead author is funded by the National Institute for Health Research (NIHR) Specialist Biomedical Research Centre for Mental Health at the South London and Maudsley NHS Foundation Trust and Institute of Psychiatry, King’s College London.
For full paper: Sosa, A.L. et al. ‘Prevalence, Distribution, and Impact of Mild Cognitive Impairment in Latin America, China, and India: A 10/66 Population-Based Study’ (7th February 2012) PLoS Medicine doi: 9(2): e1001170. doi:10.1371/journal.pmed.1001170