A large-scale study (7000) of adults 50+ has definitively shown that online mental exercises works to keep minds sharp and help people with everyday skills such as shopping and cooking. The study lasted 6 months, with the volunteers divided into a training group which played online brain training games 10 minutes at a time, and a control group which only performed online searches. Those in the training group who played at least 5 times per week showed benefits, and those 60 and above reported better scores for carrying out essential everyday tasks. Links to articles about the study, together with a link to the published work, have been posted in Mental Agility:
Online brain training ‘helps older adults with everyday tasks’
Brain training improves memory and performance of everyday tasks in older people