Sonnen et alArticle emphasize that Alzheimer disease, cerebral vascular brain injury, and isocortical Lewy body disease are the major contributors to dementia in the following community- and population-based studies: Adult Changes in Thought study (ACT), Honolulu-Asia Aging Study (HAAS), Nun Study (NS), and Oregon Brain Aging Study (OBAS). However, the prevalence of clinically silent forms of these diseases in cognitively normal (CN) adults is less clear. They evaluate 1672 brain autopsies from the ACT study, HAAS, NS, and OBAS, of which 424 met the criteria for CN. Their data show an individually varying complex convergence of subclinical diseases in the brain of older CN adults. Appreciating this ecology should help guide future biomarker and neuroimaging studies and clinical trials that focus on community- and population-based cohorts.