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 involving 70 older adults (60-83) has found that those with at least ten years of musical training performed the best on cognitive tests, followed by those with one to nine years of musical study, with those with no musical training trailing the field.

A study following 837 people with

Supporting earlier research, a study involving 8,534 older adults (65+; mean age 74.4) has found those who were obese in middle age had almost four times (300%) more risk of developing dementia. Those who were overweight in middle age had a 1.8 times (80%) higher risk of developing dementia.

A study in which mice were exposed to polluted air for three 5-hour sessions a week for 10 weeks, has revealed that such exposure damaged neurons in the

Adding to the growing evidence that social activity helps prevent age-related cognitive decline, a longitudinal study involving 1,138 older adults (mean age 80) has found that those who had the highest levels of social activity (top 10%) experienced only a quarter of the rate of cognitive declin

A study involved 117 older adults (mean age 78) found those at greater risk of coronary artery disease had substantially greater risk for decline in verbal fluency and the ability to ignore irrelevant information. Verbal memory was not affected.

A study involving 200 older adults (70+) experiencing a stay in hospital has found that at discharge nearly a third (31.5%) had previously unrecognized low cognitive function (scoring below 25 on the MMSE if high-school-educated, or below 18 if not).