How quickly does the risk of Alzheimer's disease increase as you get older?
The risk of Alzheimer's disease clearly increases with age, but the risk within each age group has remained stable over recent decades. An ageing population is driving the growing number of cases worldwide, which makes factors you can influence all the more relevant.
Your age is the strongest predictor of Alzheimer's disease. In Europe, an average of 5.05% of the population has the condition, but that figure rises sharply in older age groups. Each year, roughly 11 in every 1,000 Europeans receive the diagnosis for the first time.
Women are affected more often than men. In Europe, the share of women living with the condition is 7.13%, compared with 3.31% for men. Looking at new cases per year: women account for 13.25 new cases per 1,000 people annually, men for 7.02. This difference has been found worldwide and in China as well, but the available research does not allow us to say why women are more susceptible.
Globally, the absolute number of new cases per year rose from just over 4 million in 1992 to nearly 10 million in 2021. That doubling sounds alarming, but it is almost entirely explained by an ageing population and population growth: the risk within each age group itself remained virtually unchanged over those thirty years. The condition is not becoming more dangerous as such; there are simply more people reaching the ages at which risk is high.
Looking ahead to 2036, projections estimate that the annual number of new cases worldwide will rise to nearly 19 million. Here too, an ageing population is the driving force, not a rising risk per person. For you personally, this means that growing older substantially increases the chance of Alzheimer's, but that the risk within each age group has remained stable: lifestyle and other factors you can influence therefore genuinely matter.
This answer draws on two large summaries of European and worldwide research, and an overview of studies among older adults in China (more than 626,000 participants). The European and global figures come from broad analyses with large numbers of participants and are considered reliable. The Chinese figures are somewhat more variable due to differences in how studies diagnosed Alzheimer's. Projections to 2036 are model estimates and are therefore inherently uncertain.