The research, published in the online issue of journal journal Neurology, looked at 1,978 people with an average age of 80 who did not have dementia at the start of the study and were followed for seven years.

 

People with the highest levels of activity, on average, developed dementia at age 94. The people with the lowest cognitive activity, on average, developed dementia at age 89, a difference of five years.

 

"The good news is that it's never too late to start doing the kinds of inexpensive, accessible activities we looked at in our study," said Robert S. Wilson, from Rush University Medical Center in Chicago.

 

"Our findings suggest it may be beneficial to start doing these things, even in your 80s, to delay the onset of Alzheimer's dementia," Wilson added.

 

To test the idea that low cognitive activity may be an early sign of dementia, not the other way around, researchers also looked at the brains of 695 people who died during the study.

 

Brain tissue was examined for markers of Alzheimer's like amyloid and tau protein deposits, but researchers found no association between how active they were cognitively and markers of Alzheimer's disease and related disorders in their brains.

 

"It is important to note, after we accounted for late life level of cognitive activity, neither education nor early life cognitive activity were associated with the age at which a person developed Alzheimer's dementia. Our research suggests that the link between cognitive activity and the age at which a person developed dementia is mainly driven by the activities you do later in life," Wilson noted.