we hold that design of trials must be informed by the principle of an inverted U-shaped association between nutrient levels and function. Basic work on cognitive and neural plasticity, for example[22,25], may also be helpful for the design of lifestyle interventions, and especially for cognitive training interventions. In our opinion, it is crucial that transfer tasks are elevated to the primary outcome measures for future trials on the effects of cognitive training interventions. Ongoing trials, such as the multidomain Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability and the Multidomain Alzheimer Preventive Trial,[32] incorporate several of these design features. The evidence on the utility of lifestyle changes for preventing dementia will be much clearer in a few years.