The effects of childhood abuse last long into adulthood. The latest study to support just that suggests abuse-associated brain changes (aka “limbic scars”) worsen the severity and frequency of depression in later life.
Researchers at the University of Münster analyzed brain scans of more than 100 people aged 18 to 60 admitted to hospital on depression-related charges, each receiving inpatient treatment for a major depressive episode. They then compared the scans to the patients’ responses to a 25-point questionnaire relating to the severity of their depression and any abuse they may have had as a child, whether that abuse was physical, emotional, or sexual. The results have been published in Lancet Psychiatry.
In sum, the researchers found that those who had reported abuse had developed smaller insular cortexes on average than those who had not. This is an important discovery, they say, because, among other things, the insular cortex is involved in emotional regulation and self-awareness. Hence, it is these structural changes to the brain that they believe increases the chances of relapse later on.
Out of the original pool of 110 patients, 75 had relapsed within a two-year period – 48 experiencing one additional episode, 7 experiencing two, and six experiencing three. The remaining 14 had a remission period of two months or less, which meant they were put down as having chronic depression.
The researchers found that maltreatment in childhood was "significantly associated" with depression after the two-year follow up. Indeed, based on the results of this study, it could raise the risk of relapse by as much as 35 percent.
"Our findings add further weight to the notion that patients with clinical depression who were mistreated as children are clinically distinct from non-maltreated patients with the same diagnosis," lead author Nils Opel, from the University of Münster, Germany, said in a statement.
"Given the impact of the insular cortex on brain functions such as emotional awareness, it's possible that the changes we saw make patients less responsive to conventional treatments. Future psychiatric research should therefore explore how our findings could be translated into special attention, care and treatment that could improve patient outcomes."
Previous studies have linked childhood abuse with changes to brain structure or found associations between abuse and increased depression risk. But this appears to be the first to directly link abuse and brain structural alterations with unfavourable clinical outcomes in severe depression – and to also suggest the physical changes or limbic scars that may be involved.
That's not to say it doesn't have its limitations, not least that the experiences of childhood abuse and depressive symptoms were self-reported and retrospective. Psychotherapeutic treatment was also not standardized across patients, so the team can't rule out the possibility that differing forms of treatment may have biased their findings. The study also didn't account for trauma people may have experienced in their adult life. The researchers acknowledge more work need to be done.
"A key remaining question is whether, in the sample investigated in the study by Opel and colleagues, the observed reduction in insular surface area reflects a stable trait or normalizes over time with remission of depression, since in their previous study the researchers only reported how longitudinal changes in cortical thickness – but not surface area – fluctuate with depression relapse," Lianne Schmaal from the University of Melbourne, Australia, wrote in a linked comment.
"[This] study is an important contribution to our knowledge of mechanisms that confer risk for depression relapse. A better understanding of these mechanisms is crucial to develop or improve risk-adapted interventions for people susceptible to a worse long-term clinical outcome."