As the global population ages, due to advances in medicine and other developments leading to longer life expectancies, interest in what leads to a healthier old age is increasing. Chief among the concerns older adults might have to face is the onset of dementia, as a team of Japanese researchers highlights in the opening to their new paper studying the relationship between adverse childhood experiences and incidence of dementia in older Japanese adults. “Approximately 47 million people had dementia in 2015 worldwide,” the researchers open, “and this number is expected to triple by 2050.” Research has demonstrated that overall health has a crucial impact on chances of developing dementia, but in a recent model, “education showed the second highest percentage in terms of the contribution to the onset of dementia,” which the researchers believe demonstrates the importance of childhood experiences to the later risk of developing this dreaded disease. The researchers speculate that “adverse childhood experiences”—which includes loss of a family member, family psycopathology, and child maltreatment—may play a role in the risk of developing dementia, as previous research has demonstrated that “individuals who experienced adverse childhood experiences showed deficits in brain structure and function.” Japan, the researchers continue, is a “unique case” to study the relationship between adverse childhood experience and risk of dementia for two reasons. First, the Japanese are noted for their longevity. Second, older Japanese adults experienced the consequences of being reared amidst (or shortly after) World War II. To conduct their study, the researchers used data from the Japan Gerontological Evaluation Study, a large-scale survey administered to older Japanese adults (over 65 years of age) in 2013. This data was then linked to the incidence of depression by 2016. Survey participants were born between 1915 and 1948.