Adverse Childhood Events Tied to Dementia

Children who had multiple adverse experiences growing up were more likely to develop dementia in old age, Japanese researchers reported.

People who had three or more adverse childhood experiences -- physical or psychological abuse, family psychopathology, or loss of a parent -- had twice the risk of developing dementia in later years as other older adults, even after taking into account economic hardship, demographics, education, and nutritional environment, according to Yukako Tani, PhD, of Tokyo Medical and Dental University, and co-authors.

The connection was weaker after adjusting for social relationships, health behavior, and health status, suggesting that these factors may mediate the association between adverse childhood experiences and dementia, the team wrote in JAMA Network Open.

Childhood poverty has been linked to lower cognitive performance in old age, but associations between dementia and other early adverse experiences have not been well studied, Tani noted. "This study provides the possibility that preventing adverse childhood experiences might be important in preventing dementia," she told MedPage Today.

"Adverse childhood experiences have been previously linked to increased risk of several diseases, but the association with dementia was not clear," Tani added. "We examined this association using a large-scale cohort study of an aging society in Japan, and found that three or more adverse childhood experiences were associated with dementia incidence among older Japanese adults."

This is "an incredibly valuable and important contribution to research demonstrating that social conditions, including social adversity, are important for later-life memory health and dementia risk," observed Megan Zuelsdorff, PhD, of the University of Wisconsin in Madison, who was not involved with the study.

"Dementia risk and protection really does begin in childhood," she told MedPage Today. "The biological stress processes that are activated when trauma -- especially chronic trauma -- is experienced are not only directly toxic to brain cells and structures, but can provoke dysregulation of immune, endocrine, and cardiovascular systems and actually age us prematurely, making us more vulnerable to age-related diseases like hypertension, diabetes, and dementia earlier in life."

"With all the characteristics the research team was able to look at -- education access, financial hardship as an adult, depression -- they were able to illustrate something really important," Zuelsdorff added. "Adverse events don't happen in isolation. They ripple outward and often create more hardship, putting you at risk for more trauma. If you experience abuse or neglect, you're at risk for leaving school earlier than you might have hoped, earlier than your peers, and that changes the trajectory of your life."

In this study, Tani and her team looked at 17,412 participants in the Japan Gerontological Evaluation Study, a population-based cohort study of adults ages 65 and older. The researchers used public long-term care insurance records to assess dementia onset and data from baseline surveys conducted in 2013 to determine adverse childhood experiences.

The cutoff point on the scale that defined dementia corresponded to a score of 16 on the Mini-Mental State Examination (moderate dementia). The adverse childhood experience questionnaire consisted of seven questions about whether the participants had experienced interpersonal loss (parental loss or divorce), family psychopathology (parental mental illness or family violence), or abuse and neglect (physical abuse, psychological neglect, or psychological abuse) before age 18.

The average age of the sample was 73.5, and 53% were women. Dementia occurred in 703 people during a mean follow-up of 3.2 years.

Among all 17,412 participants, 10,968 (63.0%) reported no adverse childhood experiences; 5,129 (29.5%) reported one experience, 964 (5.5%) reported two experiences, and 351 (2.0%) reported three or more. The most common adverse experiences were parental death (22.6%) and psychological neglect (12.2%).

After accounting for age, sex, childhood economic hardship, nutritional environment, and education, people who had three or more adverse events were twice as likely to develop dementia (HR 2.18, 95% CI 1.42-3.35).

Further adjustment for potential mediators -- adult sociodemographic characteristics, social relationships, health behavior, and health status -- weakened the relationship, but it still was significant (HR 1.78, 95% CI 1.15-2.75; P=0.009), the researchers reported.

Physical abuse (HR 2.61, 95% CI 1.65-4.14), psychological neglect (HR 1.26, 95% CI 1.02-1.55), and psychological abuse (HR 1.65, 95% CI 1.23-2.20) were associated with dementia incidence. Associations between dementia and physical abuse or psychological abuse remained after adjusting for potential mediators.

Parental death alone was not associated with the risk of dementia in old age, but became a factor if the child also experienced neglect or abuse. In men, dementia was tied to physical abuse; in women, it was tied to psychological neglect or psychological abuse. A dose-response association between adverse childhood experiences and dementia incidence emerged for women, but not for men.

The study had several limitations, Tani and colleagues noted. The cutoff point used to define dementia may have missed dementia cases, and retrospective surveys, which are subject to recall bias, were used to assess adverse childhood experiences.

The findings are limited to an older society in Japan. The study did not directly assess the experience of World War II: people who had severe war experiences also may have had multiple adverse childhood experiences, the researchers added.

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