“The first large trial of a multimodal lifestyle intervention combined with a nutritional supplement for dementia prevention was unsuccessful and adds to conflicting evidence from similar studies. Whether lifestyle interventions are biologically ineffective or whether the lack of efficacy is due to methodological limitations remains to be determined.” Selection of participants was pointed out as one possible factor, since the trial population might have been enriched with relatively healthy individuals who had a low probability of cognitive decline. Additional factors are discussed.
Scarmeas N: Dementia: Multimodal dementia prevention – does trial design mask efficacy? Nature Reviews Neurology 13(6): 322-323 (2017).