Some epidemiological studies have showed that people who smoke tend to have lower incidences of Parkinson's disease and Alzheimer's disease; this has been widely attributed to nicotine. However, nicotine's harmful effects make it a poor drug candidate.

A study following 837 people with

A review of 23 longitudinal studies of older adults (65+) has found that small amounts of alcohol were associated with lower incidence rates of overall dementia and Alzheimer dementia, but not of

A two-year study involving 53 older adults (60+) has found that those with a mother who had Alzheimer's disease had significantly more brain atrophy than those with a father or no parent with Alzheimer's disease.

Data from the Baltimore Longitudinal Study on Aging, begun in 1958, has revealed that seniors with hearing loss are significantly more likely to develop dementia than those who retain their hearing.

Research into the link, if any, between cholesterol and dementia, has been somewhat contradictory. A very long-running Swedish study may explain why.

A study involving 360 patients with degenerative dementia (109 people with dementia with

Clinical records of 211 patients diagnosed with probable Alzheimer's disease have revealed that those who have spoken two or more languages consistently over many years experienced a delay in the onset of their symptoms by as much as five years.