Environmental factors account for at least half of the existence of susceptibility to Alzheimer's disease in older people more than genetic factors. Researchers believe that providing interventions among the elderly to maintain cognitive function leads to slowing or delaying the onset of the disease and may reduce the overall incidence of Alzheimer's disease in the population.

a 5-year catamnestic study of 662 pairs of twins over 50 years of age, none of whom were diagnosed with Alzheimer's disease at the start of the study.