According to new research published in the scientific journal Psychoneuroendocrinology, people who have had negative childhood experiences are biologically older than their peers.
Adverse childhood experiences are a collection of potentially traumatic events that occur before the age of adulthood. These include various forms of abuse and neglect, witnessing intimate partner violence, parental death or serious illness, parental divorce or separation, and a family member's psychiatric illness. In contrast, biological aging refers to the accumulation of damage and loss of function in cells, tissues, and organs.
Previous research has found that people who have had negative childhood experiences are more likely to develop chronic diseases and live shorter lives. The researchers wanted to know if accelerated biological aging could help explain the link between adverse childhood experiences and poor health outcomes later in life.
"This work was part of a team effort at McMaster University led by Dr. Dawn Bowdish to better understand the factors that influence individuals' health trajectories over the life course," said corresponding author Chris Verschoor, a scientist at the Health Sciences North Research Institute and assistant professor at McMaster University and the Northern Ontario School of Medicine.
"I am fascinated by the determinants of health and immunity in older adults, especially how they interact with a person's biology." This study provided a once-in-a-lifetime opportunity to quantify how different types of early life adversity affect a person's 'biological age' 30 to 60 years later."
The researchers examined data from the Canadian Longitudinal Study on Aging, a long-term study of adult development and aging that enrolled 50,000 Canadians aged 45 to 85 at the time of recruitment.
The study included 23,354 people who had completed a 90-minute interview as well as physical and clinical assessments. The researchers looked at albumin, creatinine, glycated hemoglobin (HbA1C), C-reactive protein, lymphocyte percentage, mean cell volume, red blood cell distribution width, and white blood cell count as biomarkers of biological aging.
The participants' average age was 59, and the majority (63 percent) reported having had at least one negative childhood experience. Participants who reported adversity in childhood were biologically older than those who did not. Furthermore, the researchers discovered a stronger link between adverse childhood experiences and biological age for more severe forms of adversity, such as physical and sexual abuse.
According to Verschoor, the findings suggest that "harms in early life can take many forms, and can lead to health consequences many years later." "Our research shows that these consequences manifest as perturbations to multiple biological systems, which can be measured using blood biomarkers."
However, the researchers noted that nearly all of the observed effect sizes were small. Adverse childhood experiences were also linked to educational level and smoking status, both of which were linked to biological age. Future research using longitudinal data, according to the study's authors, could help us better understand the factors that link adverse childhood experiences to biological age.
"What our study does not show is whether the biological changes we discovered were caused by the early life events themselves, or by other events or risky behaviors that occurred later in life as a result," Verschoor explained.
"As previously stated, this was a collaborative effort that could not have occurred without the participation of the Canadian Longitudinal Study on Aging and the involvement of fantastic collaborators," he added. "In particular, Dr. Oxana Mian, the post-doctoral fellow who did the majority of the work, Dr. Dan Belsky of Columbia University, and Dr. Andrea Gonzalez of McMaster University."