From 11.4 million to 24.7 million a year
About 11.4 million people developed dementia worldwide in 2023. That figure is projected to reach 24.7 million new cases a year by 2050, according to new global estimates led by the Centre for Healthy Brain Ageing at UNSW Sydney and published in JAMA Neurology.
The researchers pooled data from more than 287,000 person-years of follow-up, during which 3,001 participants developed dementia. The global age- and sex-standardised incidence rate was 9.7 new cases per 1,000 person-years.
Women and lower-income countries carry more of it
After adjusting for age, incidence was higher among women at 10.6 cases per 1,000 person-years, compared with 8.6 among men. The study did not establish why. Researchers pointed to possible factors including the higher frequency of Alzheimer's disease among women, hormonal changes around menopause and metabolic conditions that affect heart health.
The gap between rich and poor countries was wider still: 13.6 new cases per 1,000 people in low- and middle-income countries against 8.3 in high-income countries. Population ageing means the absolute growth will be concentrated where health systems are least prepared to absorb it.
What can change the curve
Dementia has no cure, but the risk is not fixed. Studies estimate that a large share of cases is linked to modifiable factors such as untreated high blood pressure, midlife obesity, smoking, high blood sugar, hearing loss and social isolation. Public health researchers argue that acting on those factors earlier would reduce the number of future cases rather than merely treating them.
The authors of the new study made a similar point: waiting for people to develop dementia and then responding is not a plan. They called for work across the whole chain, from risk reduction and earlier identification of high-risk patients to better diagnosis, treatment and care.
The economic weight is already visible. Families provide most dementia care without pay, and the cost of formal care rises steeply as the condition advances. Those costs will grow faster than the number of cases, because the fastest growth is expected in countries where formal care systems are thin.