Summary: The occurrence of dementia in old age depends on non-modifiable factors (such as age, sex, genetic, and family conditions) but also a number of potentially modifiable risk factors (hearing loss, brain injuries, obesity, hypertension, diabetes, depression, social isolation, lack of physical activity, lack of education, alcohol abuse, smoking, and air pollution). Effective interventions that could contribute to a significant reduction in the number of dementia in society should be multi-directional and undertaken at the individual and population levels.