Early life adversity impacts cognitive function in later adulthood

New findings suggest that allostatic load mediates the association between early life adversity and global cognition, as well as executive function. This research was published in the scientific journal Psychoneuroendocrinology.

“I was personally interested in this topic because of my lived experience having a grandparent with Alzheimer’s disease. It was the catalyst for my interest in understanding modifiable factors that can preserve cognitive health with aging” said study author Danielle D’Amico (@daniellendamico), a doctoral candidate at Toronto Metropolitan University.

“Throughout my studies, I became interested in life course models of cognitive aging, as more and more research is showing that age-related cognitive decline and risk of dementia can be prevented and detected decades before older adulthood. I am specifically interested in early life because childhood and adolescence is a critical period of brain development that sets the tone for cognitive aging throughout the life course.”

Cognitive function has implications for well-being, such as one’s quality of life, independence, and risk of developing a neurodegenerative disease. Chronic stress can negatively impact cognitive function; notably, during early life, the nervous system is especially sensitive to the effects of chronic stress. However, the mechanism through which chronic stress influences cognitive function is unclear.

One possible explanation is allostatic load, which “refers to multisystem physiological dysregulation due to cumulative wear-and-tear from chronic stress.” Prior studies have linked early life adversity with higher allostatic load in adults, as well as poorer cognitive function, suggesting it may mediate the association between early life adversity and later life cognitive function.

A total sample of 1541 participants were included in this research. Participants were drawn from the National Survey of Midlife in the United States (MIDUS) conducted between 2004-2006. Participants provided sociographic and health-related information, such as sex, age, education level, race, medical diagnoses and medication use (eg, hypertension, use of antidepressants in the past month).

They responded to numerous questions assessing perceived socioeconomic position, current levels of physical activity, substance use (ie, alcohol and cigarettes), and childhood trauma (ie, physical/sexual/emotional abuse, physical/emotional neglect). Biological assessments were conducted during overnight visit to three clinics, for 20 biomarkers “to index functioning of the neuroendocrine, immune, metabolic, and cardiovascular systems.”

Seven areas of cognitive function were measured via various batteries of neurocognitive tasks; these areas included immediate and delayed verbal episodic memory, working memory span, verbal fluency, inductive reasoning, processing speed, and attention switching.

“Adversity experienced in early life is associated with poorer cognitive health in middle and later life,” D’Amico told PsyPost. “This relationship can be explained by biological dysregulation from chronic stress that builds up in the body over time, otherwise known as allostatic load. In the current study, these effects were apparent only for executive functioning (higher order processes like problem solving and multitasking), but not memory performance. Also, the effects were only seen in women, not men.”

With regard to study limitations, the researcher said, “Overall, the study sample was relatively healthy with low levels of stress, low allostatic load, and performed well on the cognitive tasks. Also, the vast majority of the sample self-identified as White, which limits the ability for us to generalize the findings to other racial and ethnic groups. This is important in aging research because previous research has shown that the risk of cognitive decline and dementia differs between racial and ethnic groups.”

D’Amico added, “Another caveat is that the study design was cross-sectional – measurement of early life adversity, the biological markers making up the allostatic load score, and the cognitive tasks all took place in the same time frame. This makes it difficult for us to make causal claims about the results. For example, those with poorer cognitive performance might have reported less adversity in early life due to poorer recall.”

As for future research, the author said, “The findings need to be replicated in other samples to see how the results hold up in different populations. We also want to understand how healthy behaviors can lower allostatic load and minimize the effects of early life adversity and cognitive health in later years. Based on prior research, these healthy behaviors include physical activity, social engagement, consuming a healthy diet, and managing stress through relaxation techniques.”

The study, “The mediating role of allostatic load in the relationship between early life adversity and cognitive function across the adult lifespan”, was authored by Danielle D’Amico, Maya E. Amestoy, and Alexandra J. Fiocco.

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