Researchers at the Mayo Clinic found that elderly people who are computer savvy and physically active decrease their likelihood of developing dementia. 

For the study, researchers surveyed 926 people aged 70 to 93 in Olmstead County, MN on their daily activities, including activities deemed physically and mentally stimulating.  Participants who reported moderate computer use, combined with five to six mild workouts per week, were least likely to display age-related memory loss. 

Bottom line: Accept your grandmother's Facebook friend request.