The effects of physical exercise on cognition in low-performing individuals provide hopes that such intervention may reduce conversion to clinical dementia. This was directly studied in a RCT of Tai Chi training[18••]. The intervention group (n = 171; mean age = 77 years) was compared with a stretching and toning control group (n = 218; mean age = 78 years). Participants were training for at least 30 min per day and at least 3 days per week over a period of 12 months. Results showed that deterioration to clinical dementia as diagnosed by DSM-IV at the posttest (12-month) assessment tended to be more frequent in the control group (17%) than in the intervention group (4%). Training-related effects on cognitive outcome variables were, however, not observed, limiting the conclusions that can be drawn from this trial. Nevertheless, this study is important because it directly addresses effects of changes in physical activity on the incidence of dementia, and provides some preliminary support suggesting that such lifestyle change may reduce incidence of dementia. In our view, future research must continue this line of work and include dementia diagnosis as an outcome, as well as consider several forms of physical activities as useful targets for intervention.