Ten people reported no activities, and 11 reported only one activity per week.

The researchers then looked at the point when memory loss started accelerating rapidly for the participants. They found that for every additional activity a person participated in, the onset of rapid memory loss was delayed by 0.18 years.

'The point of accelerated decline was delayed by 1.29 years for the person who participated in 11 activities per week compared to the person who participated in only four activities per week,' said study author Charles B. Hall, Albert Einstein College of Medicine in the Bronx, NY.

The results remained valid after researchers factored in the education level of the participants. 'The effect of these activities in late life appears to be independent of education,' Hall said.

The study was published in the Tuesday issue of Neurology.