Geriatric Demography and Its Implications

Population ageing is the rise in both the number and the proportion of older persons. It has two components: absolute ageing (more people surviving to old age, driven by rising life expectancy) and relative ageing (a higher proportion of older adults, driven by falling fertility). Pathy’s makes exactly this distinction — “Increases in life expectancy around the world have led to absolute ageing of the global population” while “Declining fertility rates are also leading to a phenomenon of relative ageing.”

The core demographic indicators you must be able to define:

WHO estimates that the population over age 60 will approximately double from 2015 to 2050, when 20% of the world’s population will be over 60. The majority of these older adults will reside in low- and middle-income countries, providing global challenges to ensure they receive adequate access to healthcare and other resources.

The scale of the change in life expectancy: “In 1950, the average life expectancy was 49 years (68 in developed countries), as compared to 72 (79 in developed countries) in 2019.” The United Nations projects only modest further increases, and “due to biologically and physiologically fixed mechanisms, it seems unlikely that, as a species, human life expectancy will ever exceed approximately 115 years of age.”

The 80+ group is the critical one. Pathy’s states that “at present, the over-85 population is the fastest-growing age group in developing countries.” This matters clinically because disability, multimorbidity, dementia and dependency all cluster in the very old.

Causes of absolute ageing: “Improved sanitation, nutrition, and living conditions, as well as major healthcare innovations such as effective treatments for infectious diseases, vaccinations, and advances in neonatal care.” Pathy’s adds that “management of chronic diseases, particularly cardiovascular and oncologic diseases, has also led to extended life expectancy in adulthood and older age.”

Causes of relative ageing (falling fertility): “improved access to birth control, declining numbers of teenage pregnancies, increased female engagement in the workforce, a higher percentage of women pursuing advanced education, and delays in the average age of marriage.” The decline “is more pronounced in developed countries, but the trend is seen globally.”

Two great transitions run in parallel: the demographic transition (high birth/high death → low birth/low death) and the epidemiological transition (communicable, maternal and perinatal diseases → non-communicable, chronic and degenerative diseases). The result in India is the “double burden” — infections persist while NCDs rise.

Rectangularisation of the survival curve. Pathy’s Chapter 1 explains that “medicine delays the death of most individuals of a given generation until they are closer to maximum lifespan, but it does not change the maximum lifespan much.” Fries interpreted this “compression of mortality” as the result of a “compression of morbidity” — based on the facts that there is a maximum lifespan, that even without chronic disease individuals would still die, and that chronic diseases can be prevented. Related is the concept of healthspan — the duration of life in good health.

Compression vs expansion of morbidity — the central policy question. If morbidity compresses, extra years are healthy years and the health-system burden is contained; if it expands, extra years are years of disability. Pathy’s also notes the “late-life mortality plateau” — after 80 the incidence of death still increases but progressively more slowly — and reminds us that Jeanne Calment died at 122.

Why women predominate in old age. Pathy’s: “At birth, the male to female birth rate is approximately 1.05:1. However, females generally have a longer life expectancy than males, which leads to a shifting of the gender ratio in older adults, such that females outnumber males.” Reasons given: oestrogen may be protective against cardiovascular disease; women are less susceptible to X-linked genetic disorders; males are more likely to engage in high-risk behaviour including dangerous occupations, reckless driving and substance use; political upheaval and wartime have disproportionately affected men (Russia shows an almost 11-year male–female gap); and women generally engage with medical care and seek attention earlier than men.

The gap widens with age. In the US in 2020, females outnumbered males 1.1:1 at age 65, 1.2:1 at 75, 1.5:1 at 85, and 2.5:1 at 95. The gender gap is expected to narrow as cardiovascular mortality improves and as women take up workforce participation and smoking at higher rates.

Important exception for India — quote this. Pathy’s states that in developing countries, “due to less access to education and healthcare, higher rates of physical abuse, and risk of poverty in widowhood, women have lower life expectancies, resulting in female to male ratios closer to 1,” and that “India and China, which have historically practised female infanticide, have significantly more males than females, and these effects extend into older adulthood.” (Note: current Indian data now show the elderly sex ratio has crossed 1,000 — see updates.)

Headline projections: India’s 60+ population will rise from 149 million in 2022 (about 10%) to 347 million by 2050 (more than 20%), and by mid-century the elderly will outnumber children. The Government projects a rise from 100 million in 2011 to 230 million by 2036, forming 15% of the total population — so by 2036 nearly one in seven Indians will be aged 60 or older. LASI shows the 60+ share moving from 6.9% (2000) → 11.4% (2025) → 19.5% (2050).

The ageing of the aged and the widowhood problem: the 80+ population will grow by about 279% between 2022 and 2050, with “a predominance of widowed and highly dependent very old women.” More than half of India’s women over 60 are widowed, rising in higher age cohorts. The elderly sex ratio is now 1,065 females per 1,000 males; 58% of the elderly are women, of whom 54% are widows. In central India it rose from 973 (2011) to 1,053 (2021), and poverty in old age is inherently gendered — older women are more likely to be widowed, living alone, with no income and fewer assets.

The North–South divide — a distinctly Indian feature: “By 2036, one in five people in India’s southern states will be elderly. The north–south divide… is an important feature of India’s ageing.” Kerala will have the highest elderly share (23% by 2036), while Uttar Pradesh will see the fastest growth in elderly numbers. Life expectancy at 60 is higher for women, with a national differential of only 1.5 years but 4 years in Kerala and Himachal Pradesh, where women at 60 can expect 22–23 more years.

Dependency and the demographic dividend: India’s old-age dependency ratio is expected to reach 31.5 by 2050, against a child dependency ratio of 29.8 per 100 persons aged 15–59. India’s median age is about 29 (2026) — Kerala ~33, Bihar ~22 — with TFR at 2.0 (NFHS-5), already below the replacement level of 2.1, and the demographic dividend expected to peak around 2036–2041 and close by 2055.

India’s transition is COMPRESSED — the sentence that wins marks: “Developed countries underwent their demographic transitions gradually over several decades, allowing time to build robust social security systems, healthcare infrastructure, and pension schemes. In contrast, developing nations like India are experiencing compressed demographic transitions, with ageing occurring at unprecedented speed while economic development and social support systems struggle to keep pace.” India is growing old before it grows rich.

Implications, organised by domain:

Three caveats that separate a good answer from an average one: The dependency ratio is an imperfect measure. Pathy’s: “It does not account for adults who work past the age of 65 or improvements in care and advances in technology that reduce the societal burden of ageing and disability. Although the old-age dependency ratio will certainly increase globally, the economic and societal implications remain uncertain.” Older people are not uniformly disabled. Essentials: “Because physicians tend to see the sick, they may form a distorted picture of senior citizens. Most older persons are indeed self-sufficient and able to function on their own or with minimal assistance.” In US data, ADL dependency rose from 23% at ages 65–84 to 48% at 85+, and IADL dependency from 23% to 43% — so even at 85+, roughly half remain independent. The elderly population is profoundly heterogeneous. Pathy’s: “Each elderly individual is unique, and the elderly population is heterogeneous. A 65-year-old person may be immobile, while a 90-year-old may be mobile and completely independent in their activities of daily living.” Chronological age is a poor guide; function and intrinsic capacity are better.

India Ageing Report 2023 (UNFPA–IIPS) — now the standard reference. Projects the 80+ population growing by about 279% between 2022 and 2050 with a predominance of widowed and highly dependent very old women, and shows women have higher life expectancy at both 60 and 80, with wide state variation (four years’ advantage in Kerala and Himachal Pradesh vs a national average of 1.5 years). States lagging in the transition, such as Bihar and Uttar Pradesh, will see the elderly share rise between 2021 and 2036 but remain below the national average; central and north-eastern regions are “younger” than southern and western India on the ageing index. Also: over 40% of the elderly in the poorest wealth quintile, 18.7% with no income, and 71% living in rural areas.

Official government projection now widely quoted. MoSJE states India’s elderly population is projected to more than double from 100 million in 2011 to 230 million by 2036 — nearly one in seven Indians aged 60 or older by 2036, “a fundamental restructuring of the country’s population composition” — with southern states plus Himachal Pradesh and Punjab already having higher elderly populations and regional disparities expected to widen.

Feminisation is now measurable and reverses the older textbook position. The elderly sex ratio is 1,065 females per 1,000 males, with 58% of the elderly being women and 54% of them widows, and the overall dependency ratio at 62 dependents per 100 working-age individuals. The elderly sex ratio has been climbing steadily since 1991, with central India moving from 973 (2011) to 1,053 (2021). This directly updates Pathy’s statement that India has “significantly more males than females… extending into older adulthood.”

Fertility below replacement and a closing dividend window. India’s TFR is now 2.0 (NFHS-5, 2019–21), below the replacement level of 2.1, and its median age is about 29 in 2026 (UN WPP 2024 and NSO), with Kerala at ~33 and Bihar at ~22. The demographic dividend is estimated to peak around 2036–2041 and effectively close by 2055.

Global context. The UN Decade of Healthy Ageing (2021–2030) frames the response under combating ageism, age-friendly environments, integrated care and long-term care, and WHO’s 2023 progress report found fewer than one-third of countries have adequate resources. NITI Aayog (2024) describes an absence of a comprehensive, integrated senior-care policy in India.

“Population ageing has two components: absolute ageing driven by rising life expectancy, and relative ageing driven by falling fertility.”

“Medicine delays death until closer to maximum lifespan but does not change maximum lifespan much — this rectangularisation of the survival curve is Fries’ compression of morbidity.”

“India is experiencing a compressed demographic transition — ageing at unprecedented speed while social support systems struggle to keep pace. India is growing old before it grows rich.”

“The old-age dependency ratio is an imperfect measure: it ignores those working past 65 and technological gains that reduce the societal burden of disability.”

“Because physicians tend to see the sick, they may form a distorted picture of senior citizens — even at 85 and above, roughly half remain independent in ADLs.”

“A 65-year-old may be immobile while a 90-year-old is completely independent — chronological age is a poor guide; function and intrinsic capacity are better.”

Global: LE 49 (1950) → 72 (2019); ceiling ~115 years; Jeanne Calment 122; over-85s = fastest-growing group.

India: 149 m → 347 m • 10.5% → 20.8% • 80+ +279% • elderly > children by 2046 • 230 m by 2036.

Sex ratio 1,065 • 58% women • 54% widows • dependency ratio 62 per 100 • ODR 31.5 by 2050.

TFR 2.0 (below replacement 2.1) • median age ~29 • dividend peaks 2036–2041, closes 2055.

US gender gap: 1.1:1 at 65 → 2.5:1 at 95. ADL dependency 23% (65–84) → 48% (85+).

Kerala 23% elderly by 2036; women at 60 in Kerala/HP expect 22–23 more years.