Preventing cognitive decline and the emergence of dementia in later life is one of the most pressing medical challenges facing society. The causes of dementia can broadly be categorized into neurodegenerative disorders, associated with the accumulation of misfolded proteins within the brain; cerebrovascular disease of varying etiologies; and, commonly, combinations of both. As well as major efforts to develop and test pharmacological approaches to delay the onset of specific neurodegenerative diseases, and Alzheimer disease in particular (eg, NCT05026866 and Rafii et al), much can be done to reduce dementia risk via other means: evidence suggests that up to 45% of all-cause dementia may be preventable worldwide through modification of 14 risk factors (education, traumatic brain injury, hearing loss, depression, hypertension, diabetes, obesity, physical inactivity, smoking, excess alcohol intake, high low-density lipoprotein cholesterol, social isolation, exposure to air pollution, and visual loss) exerting influence at various stages throughout life. There is evidence that public health measures may already be having an impact: age-specific declines in the incidence of dementia in the US and other high-income countries have been observed in recent years and may relate in part to improved education and management of cardiovascular risk within these populations in the preceding decades.