Reading the newspaper, playing chess or doing other mentally stimulating activity has been linked to a reduced risk of developing Alzheimer's disease.
The results come from a study to be published in Neurology, the medical journal of the American Academy of Neurology.
As part of the Rush Memory and Ageing Project, which looked at the effects of mentally stimulating activity on 1,200 people, of whom 90 developed Alzheimer's.
Those participants who were cognitively active in old age were found to have 2.6 times less chance of developing the disease.
The link remained in light of past cognitive activity, lifetime socioeconomics status and current social and physical activity.
Robert Wilson, study author, said: "Alzheimer's disease is among the most feared consequences of old age. The enormous public health problems posed by the disease are expected to increase during the coming decades."
The findings, according to the researchers, may be used to help prevent Alzheimer's disease.