“We already knew childhood trauma is associated with the later development of depressive and anxiety disorders, but it’s been unclear what makes sufferers of early trauma more likely to develop these psychiatric conditions,” study investigator Erika Kuzminskaite, PhD candidate, department of psychiatry, Amsterdam University Medical Center (UMC), the Netherlands, told this news organization.
“The evidence now points to unbalanced stress systems as a possible cause of this vulnerability, and now the most important question is, how we can develop preventive interventions,” she added.
The findings were presented as part of the Anxiety and Depression Association of America Anxiety & Depression conference.
Elevated cortisol, inflammation
The study included 2,779 adults from the Netherlands Study of Depression and Anxiety (NESDA). Two thirds of participants were female.
Participants retrospectively reported childhood trauma, defined as emotional, physical, or sexual abuse or emotional or physical neglect, before the age of 18 years. Severe trauma was defined as multiple types or increased frequency of abuse.
Of the total cohort, 48% reported experiencing some childhood trauma – 21% reported severe trauma, 27% reported mild trauma, and 42% reported no childhood trauma.
Among those with trauma, 89% had a current or remitted anxiety or depressive disorder, and 11% had no psychiatric sequelae. Among participants who reported no trauma, 68% had a current or remitted disorder, and 32% had no psychiatric disorders.
At baseline, researchers assessed markers of major bodily stress systems, including the hypothalamic-pituitary-adrenal (HPA) axis, the immune-inflammatory system, and the autonomic nervous system (ANS). They examined these markers separately and cumulatively.
In one model, investigators found that levels of cortisol and inflammation were significantly elevated in those with severe childhood trauma compared to those with no childhood trauma. The effects were largest for the cumulative markers for HPA-axis, inflammation, and all stress system markers (Cohen’s d = 0.23, 0.12, and 0.25, respectively). There was no association with ANS markers.
The results were partially explained by lifestyle, said Ms. Kuzminskaite, who noted that people with severe childhood trauma tend to have a higher body mass index, smoke more, and have other unhealthy habits that may represent a “coping” mechanism for trauma.
Those who experienced childhood trauma also have higher rates of other disorders, including asthma, diabetes, and cardiovascular disease. Ms. Kuzminskaite noted that people with childhood trauma have at least double the risk of cancer in later life.
When researchers adjusted for lifestyle factors and chronic conditions, the association for cortisol was reduced and that for inflammation disappeared. However, the cumulative inflammatory markers remained significant.
Another model examined lipopolysaccharide-stimulated (LPS) immune-inflammatory markers by childhood trauma severity. This provides a more “dynamic” measure of stress systems than looking only at static circulating levels in the blood, as was done in the first model, said Ms. Kuzminskaite.
“These levels should theoretically be more affected by experiences such as childhood trauma and they are also less sensitive to lifestyle.”
Here, researchers found significant positive associations with childhood trauma, especially severe trauma, after adjusting for lifestyle and health-related covariates (cumulative index d = 0.19).
“Almost all people with childhood trauma, especially severe trauma, had LPS-stimulated cytokines upregulated,” said Ms. Kuzminskaite. “So again, there is this dysregulation of immune system functioning in these subjects.”
And again, the strongest effect was for the cumulative index of all cytokines, she said.