How Many Years of Clear Thinking Await India’s Aging Millions? New Study Weighs the Odds

India is aging faster than most people realize. By 2050, the country is projected to be home to roughly 330 million adults aged 60 or older, a population so large that it will outnumber the nation’s children for the first time in modern history. But a longer life is only a blessing if those extra years are lived with a mind intact. A new study published in SSM – Population Health has, for the first time, calculated how many years of cognitively healthy life older Indian men and women can expect, and the results reveal stark divides running along the lines of gender, geography, and caste.

The research team, led by Sneha Sarah Mani of the Longitudinal Aging Study in India collaboration together with Yuan S. Zhang, Lindsay C. Kobayashi, and Alden L. Gross, drew on an unusually rich data infrastructure. The Longitudinal Aging Study in India, or LASI, is a nationally representative survey of more than 70,000 Indian adults aged 45 and above, conducted in 2017 to 2019. Within it, a specialized sub-study called LASI-DAD administered an in-depth neuropsychological battery to 4,096 participants aged 60 and older. The battery included the Hindi Mental State Examination, word list learning and recall, digit span tests, constructional praxis, and animal naming, all adapted and validated for India’s many languages and for respondents with little or no formal schooling. Family members were also interviewed to corroborate each participant’s cognitive status.

Using an algorithm based on the DSM-5 criteria for mild and major neurocognitive disorders, the researchers classified each participant as cognitively healthy, as having mild cognitive impairment, or as having dementia. The picture that emerged was sobering: nearly a quarter of older Indian adults had some form of cognitive impairment, with 17.4 percent showing mild cognitive impairment and 7.4 percent living with dementia. Among men, the prevalence of mild impairment was actually higher, at 18.5 percent, than among women, at 16.3 percent. But women carried a heavier dementia burden, at 8.0 percent versus 6.8 percent for men, and that gap widened sharply after age 70, when 11.8 percent of women had dementia compared with 9.3 percent of men.

To convert these snapshots into life expectancy estimates, the team applied the Sullivan method, a classic demographic technique from 1971 that apportions the years in a standard life table across different health states according to the prevalence of each condition at every age. Mortality rates came from the Sample Registration System, a continuous vital-events monitoring panel that India has operated since 1971, while caste-specific mortality had to be estimated separately from household death reports in the National Family Health Survey, because official life tables are not published by caste. The result is a measure called cognitively healthy life expectancy, or CHLE: the average number of remaining years a person at a given age can expect to live free of cognitive impairment, given current mortality and prevalence patterns.

The headline numbers are striking. At age 60, Indian women can expect 14.3 years of cognitively healthy life and men 13.5 years. Both genders spend roughly 75 percent of their remaining years free of cognitive impairment, with men spending slightly more time in the mild impairment state, 3.4 years versus 3.1 for women, and women spending more time with dementia, 1.6 years versus 1.2. By age 70, both men and women have about 8.5 to 9 cognitively healthy years left, and roughly 70 percent of their remaining life is lived with an unimpaired mind. These proportions are comparable to, or worse than, those seen in wealthy countries such as the United States and England, despite India’s much shorter total life expectancy at these ages.

The regional and social fault lines, however, are where the study becomes truly revealing. Urban women at age 60 could expect 15.8 cognitively healthy years, about 2.2 more than rural women, while urban men could expect 15.3 years, a full 3.1 years more than their rural counterparts. Urban men spent 80 percent of their remaining life cognitively healthy, compared with just 72 percent for rural men. Caste gradients proved even steeper. Women from Scheduled Castes and Scheduled Tribes, historically marginalized communities, could expect only 11.6 cognitively healthy years at age 60, 3.7 fewer than higher-caste women, and they spent 31 percent of their remaining life with impairment versus 26 percent for higher-caste women. Among men, the gap was wider still: higher-caste men could expect more than five additional years of good cognitive health compared with Scheduled Caste and Tribe men, who faced roughly four times the disadvantage that Other Backward Class men did relative to the top group.

Perhaps the most technically innovative part of the study is its decomposition analysis. A gap in cognitively healthy life expectancy between two groups can arise in two ways: one group may die earlier, cutting short the years available for healthy cognition, or it may live just as long but spend more of those years impaired. Using stepwise replacement methods that swap age-specific mortality and prevalence parameters between populations, the researchers disentangled these pathways. The answer was consistent across most comparisons: mortality, not cognitive impairment prevalence, is the dominant driver of inequality. For the 3.1-year gap between urban and rural men, lower urban mortality contributed 1.6 years and lower urban impairment prevalence 1.5 years, but for caste gaps, mortality dominated overwhelmingly, contributing 2.5 of the 3.7-year gap among women and 3 of the 5.3-year gap among men.

The gender story is more nuanced. The overall gap between women and men at age 60 was small, just 0.86 years, because two opposing forces nearly cancel out. Women’s lower mortality pushes their cognitively healthy expectancy up by 0.68 years, but their higher dementia prevalence at older ages pulls it down. Only among higher-caste groups did women fare worse than men in absolute terms, with a net deficit of 0.68 years driven almost entirely by high levels of dementia among women over 70, which cost them 1.64 years and overwhelmed their survival advantage. The researchers suggest several mechanisms: women survive longer into the ages when dementia is most common, men with impairment face higher competing mortality, and men carry a heavier burden of vascular risk factors such as tobacco and alcohol use. Distinguishing among these explanations, they caution, will require longitudinal follow-up.

What explains the deep social gradients? Education looms large. Schooling is one of the most consistently protective factors against dementia, building cognitive reserve that buffers the brain against pathology, yet access to education in India has historically been rationed along precisely the lines the study examines: men over women, urban over rural, and higher castes over Scheduled Castes and Tribes. Although affirmative action policies and schooling expansion since the 1970s have narrowed some gaps, children from marginalized communities still lag in school completion today. Beyond education, the same social lines pattern early-life nutritional deprivation, occupational exposures in agricultural and informal manual labor, indoor and outdoor air pollution, and unequal access to diagnosis and management of hypertension and diabetes, all of which feed into both cognitive decline and premature death.

The policy implications are pointed. Because excess mortality, rather than dementia prevalence, drives most of the inequality in cognitively healthy life expectancy, the authors argue that interventions should prioritize the underlying causes of early death among disadvantaged groups: expanding healthcare access, controlling chronic disease through existing primary-care platforms such as Ayushman Arogya Mandirs and the National Program for Health Care of the Elderly, and addressing the social determinants that shape health across the entire life course. At the same time, reducing dementia risk remains vital, since evidence suggests prevention both adds healthy years and compresses the period of illness for those who do develop the condition. With global projections attributing a large share of the coming surge in dementia cases to South Asia, and with the Lancet Commission noting that a greater proportion of dementia risk is modifiable in low- and middle-income countries than in rich ones, the stakes could hardly be higher. The study has limitations, including the Sullivan method’s assumption of stable rates and a classification algorithm that likely underestimates impairment, but its central message stands: as India’s demographic tide turns, ensuring that the nation’s added years are thinking years will depend on closing the survival gaps that have divided its population for generations.

Subject of Research: Cognitively healthy life expectancy and dementia burden among older adults in India by gender, urban-rural residence, and caste

Article Title: Cognitively Healthy Life Expectancy of Older Women and Men in India

Article References: Cognitively Healthy Life Expectancy of Older Women and Men in India. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: India, cognitively healthy life expectancy, dementia, mild cognitive impairment, population aging, LASI-DAD, Sullivan method, health inequality, caste, rural-urban disparities, gender differences, mortality decomposition