More than two years after its release, one estimate still stands as a landmark in what we can do about dementia. In 2024 an international commission of experts estimated that about 45 percent of dementia worldwide could be prevented or delayed if 14 ordinary risk factors were fully addressed across a lifetime, and it added two new ones to its list.
The work is the Lancet Commission on dementia prevention, intervention, and care, led by Gill Livingston, which gathers the strongest global evidence and names the factors linked to risk. Its 2024 report counts 14 of them: in early life, too little education; in midlife, hearing loss, high LDL cholesterol, depression, head injury, physical inactivity, diabetes, smoking, high blood pressure, obesity, and heavy drinking; and in later life, social isolation, air pollution, and untreated vision loss. The two newcomers, untreated vision loss and high LDL cholesterol, are both things a clinic can check for and help manage, and together they account for roughly 9 percent of dementia in the commission’s model. The commission estimates that if all 14 were fully addressed, close to half of dementia could be prevented or delayed.
Why a list like this is good news
Researchers think many of these factors affect the brain through familiar channels, such as blood vessel health, inflammation, and the reserve of mental capacity built over the years. The links are strong associations, and scientists are still working out how much of each is direct cause. What makes the list encouraging is that many of the items are things a person or a family can act on, and a few, like air pollution, also depend on the places we live. Most of the factors sit in midlife, and the commission’s message is that it is never too early or too late to act. This is the fuller picture behind an idea we explored when the earlier estimate stood near 40 percent, now updated and more hopeful.
On the best evidence, almost half of dementia sits within reach of ordinary care.
The menu, and the two new dishes
The practical version is a checklist any family can keep: have hearing and vision tested and corrected, keep blood pressure, cholesterol, and blood sugar in good range, stay active and socially connected, protect the head, and avoid smoking while limiting exposure to polluted air. The two newest items are among the easiest to miss and to manage: book the eye exam and get the right glasses, and ask the doctor about cholesterol. Small, ordinary acts, each one trimming a sliver of risk.
A fair caveat: the 45 percent is a population estimate built from observational studies. It describes the share of cases that might be avoided if everyone’s risks were fully addressed, and no one can promise that for any single life. What stands is a message of real agency: a great deal of what shapes the aging brain is within reach of ordinary care, and the list of levers we can pull is still growing.