Suffering stress during childhood worsens a person’s ability to deal with it in later life, a new study shows.
Researchers found people who suffered high levels of anxiety at a young age had abnormal responses to stress in adulthood.
The levels of the stress-hormone, Cortisol, in their blood remained more constant than is healthy people, according to the findings published in the journal Psychological Science.
Cortisol levels normally peak when we wake up and decrease steadily during the day.
But the research showed childhood trauma “dysregulated” the system controlling its release.
This effect was only seen in adults undergoing high levels of stress having suffered it as children.
It was not seen when they only did during adolescence or adulthood or in adults not from suffering stress, and was not affected by the amount of stress experienced by an individual.
Study author Ethan Young, a psychological scientist at the University of Minnesota in the US, said: “What we find is that the amount of a person’s exposure to early life stress plays an important role in the development of unhealthy patterns of cortisol release.
“However, this is only true if individuals also are experiencing higher levels of current stress, indicating that the combination of higher early life stress and higher current life stress leads to the most unhealthy cortisol profiles.”
Mr Young said the flatter cortisol patterns seen in adults reporting high levels of stress after similar experiences as a child were linked with health problems.
He explained that one of the ways that our brains respond to daily stressors is by releasing the hormone Cortisol.
Typically its levels peak in the morning and gradually decline throughout the day but this system can become dysregulated.
Mr Young explained that rhis results in a flatter cortisol pattern that has been linked with “negative health outcomes”.
Mr Young made his findings after analysing data from 90 people who were part of a high-risk birth cohort in the Minnesota Longitudinal Study of Risk and Adaptation.
He wanted to investigate whether early childhood stress made our stress-response system more sensitive to stressors that emerge later in life.
The researchers used data from answers the participants, all aged 37, gave to the Life Events Schedule (LES) survey.
It assessed individuals’ stressful life events, including financial trouble, relationship problems, and physical danger and mortality.
The responses were rated the level of disruption of each event on a scale from 0 to 3 to create an overall score for that measurement period.
And the participants’ mothers completed the interview when the participants were 12, 18, 30, 42, 48, 54, and 64 months old; and when they were 16 and 17 years old.
The participants completed the LES themselves when they were 23, 26, 28, 32, 34, and 37 years old.
The researchers grouped the LES scores into early childhood (one to five-years), middle childhood, adolescence (16 and 17-years), early adulthood (23-34 years), and current (37 years).
The study participants also provided daily cortisol data over a two-day period.
They collected a saliva sample immediately when they woke up and again 30 minutes and one hour later, in the afternoon and before going to bed.
They sent the saliva samples to a lab for cortisol-level testing.
Mr Young said the results showed that neither total life stress nor early childhood stress predicted cortisol level patterns at age 37.
But the participants’ cortisol patterns depended on both early childhood stress and current levels of stress.
Those who experienced relatively low levels of stress in early childhood showed relatively similar cortisol patterns regardless of their stress level in adulthood.
But participants who had been exposed to relatively high levels of early childhood stress showed flatter daily cortisol patterns – but only if they also reported high levels of stress as adults.
The researchers found no meaningful relationship with adult cortisol patterns with life stress in middle childhood, adolescence, and early adulthood.
Mr Young said the findings suggest that early childhood may be a particularly sensitive time in which stressful life events – such as those related to trauma or poverty – occur.
And he said it can calibrate the brain’s stress-response system, with health consequences that last into adulthood.
His team warned that cortisol is one part of the human stress-response system, and plan to conduct further research on how other components, such as the microbiome in our gut, also play a role in long-term health.