Most of us worry about losing our memory and our general mental sharpness as we age - but there's plenty we can be doing right now to slow the decline.
Researchers have found that social activities that engage the brain - such as reading, writing, doing crossword puzzles, playing card and board games, and having group discussions - all help to keep us sharp.
We can even start these activities late in life, and still delay the onset of memory loss and dementia, as researchers discovered when they tested a group of 488 people aged between 75 and 85 years, who were still mentally sharp.
During the five years of the study, 101 of the group developed dementia - but researchers discovered that those who engaged their brain with one or more of the social activities were able to delay the time their mental functions began to deteriorate.
Of those who developed dementia, most took part in just one of the six activities each day, while 10 did not participate in any of the activities, and 11 reported just one activity a week - in other words, they read or wrote just once a week.
But even doing just 11 of the activities over a week - such as reading every day, and doing a crossword four days a week - meant that, on average, the onset of dementia was delayed by 1.29 years.
(Source: Neurology, 2009; 73: 356-61).