Dementia cases set to triple by 2050 unless countries address risk factors: Lancet study

The analysis forecasts dementia prevalence in 195 countries and territories and examines the impact of expected trends in exposure to four important risk factors—smoking, obesity, high blood sugar, and low education.

For India, where 3,843,118 cases were recorded in 2019, the number in expected to touch 11,422,692 in 2050. “We found increases in every country, and in India, we estimate that the number of people with dementia will increase by 197% between 2019 and 2050. These increases are due predominantly to population ageing and population growth, but trends in the prevalence of risk factors for dementia, such as smoking, obesity, and high blood sugar, are also expected to have an effect,” lead author of the study Dr Emma Nichols from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington, USA, told The Indian Express via email.

Dementia is currently the seventh leading cause of death worldwide and one of the major causes of disability and dependency among older people worldwide—with global costs in 2019 estimated at more than US$1 trillion. Although dementia mainly affects older people, it is not an inevitable consequence of ageing. A Lancet Commission study published in 2020 suggested that up to 40% of dementia cases could be prevented or delayed if exposure to 12 known risk factors were eliminated—low education, high blood pressure, hearing impairment, smoking, midlife obesity, depression, physical inactivity, diabetes, social isolation, excessive alcohol consumption, head injury, and air pollution.

“These results should act as a call to action for governments and decision-makers who should scale up the needed supports and services for individuals anticipated to have dementia in the future, and their caregivers. Policy-makers should also invest in the scale up of interventions targeting modifiable risk factors and research on potential disease-modifying drugs to stop or slow the progression of disease,” Dr Nichols said.

The study predicts that the greatest increase in prevalence will occur in eastern sub-Saharan Africa, where the number of people living with dementia is expected to climb by 357% , from nearly 6,60,000 in 2019 to more than 3 million in 2050, mainly driven by population growth. By contrast, the smallest increase in the number of dementia cases is projected in Asia-Pacific, where the number of cases is expected to grow by 53%, from 4·8 million in 2019 to 7·4 million in 2050—with a particularly small increase predicted in Japan (27%). In this region, the risk of dementia for each age group is expected to fall, suggesting that preventive measures, including improvements in education and healthy lifestyle, are having an impact.

Globally, more women are affected by dementia than men. In 2019, women with dementia outnumbered men with a 100:69 ratio. The pattern is expected to continue in 2050. “It’s not just because women tend to live longer,” says co-author Dr Jaimie Steinmetz from IHME, University of Washington, USA. “There is evidence of sex differences in the biological mechanisms that underlie dementia. It’s been suggested that Alzheimer’s disease may spread differently in the brains of women than in men, and several genetic risk factors seem related to the disease risk by sex,” Dr Steinmetz added.