Brain researchers have known for years that people who are abused in childhood often suffer serious impairments, including a high risk of developing psychiatric disorders, from anxiety and depression to addiction and suicide. Yet they have been mystified by the fact that certain individuals who are maltreated, even severely, somehow show no adverse behavioral effects.

A team of investigators led by 2005 and 2001 BBRF Independent Investigator Martin H. Teicher, M.D., Ph.D., and Kyoko Ohashi, Ph.D., both of Harvard Medical School/McLean Hospital, now shed new light on why certain people seem behaviorally resilient despite a history of maltreatment. Their study defined maltreatment as exposure to two or more types of maltreatment, and resilience as an absence of diagnosable disorders and significant behavioral symptoms.

The team was following up on its past research, published in 2017, which showed that maltreatment was associated with brain abnormalities, both in youths who suffered behavioral impacts and in those who did not.

What then is the difference, biologically, between those who are behaviorally susceptible and those who are resilient? In a paper published April 15th in Biological Psychiatry, the team reported that it had identified specific neurobiological changes that appear to enable resilient individuals to compensate for alterations caused by abuse in stress-vulnerable brain structures.

This “potential answer to the puzzle” of resilience to abuse, to use the team’s words, was based on analysis of brain scans made of 342 unmedicated individuals, aged 18-25, of whom 192 had been maltreated. The researchers made use of diffusion tensor imaging, or DTI, which enables them to trace the paths of brain fibers—specifically, those that scientists call white-matter tracts. These reveal the extent and strength of connectivity within and across brain regions.

The team found that the resilient group had abnormalities in overall brain network architecture that were “at least as strong” as those seen in the susceptible group. But the resilient participants had additional abnormalities, which ironically appear to have protected them. These other changes reduced connectivity between certain key brain areas. This, the researchers propose, may partially isolate and limit the harmful impact of susceptible components in the network, resulting in no impacts upon behavior.

One of at least nine potential differences seen in the resilient participants affected the right portion of the amygdala, a brain structure deeply involved in emotional processing. This region is hyperactive in some people who have been subjected to abuse. Reduced connectivity may compensate for this or other abnormalities in resilient individuals, although more research will be needed to demonstrate this.

Overall, these differences in network architecture were clear enough to enable the researchers to differentiate healthy controls from both susceptible and resilient maltreated individuals, with about 80% accuracy.

The scientists said their work suggests the potential of new therapeutic approaches that would aim to bring the brain circuitry of susceptible maltreated individuals “more into line with that of resilient individuals.”