A large brain imaging study led by psychologists at UCLA has found that abuse in childhood can change how the brain is built. The team studied MRI scans and compared them with how severe each person’s mistreatment had been. They looked at the thickness of the brain’s outer layer, the size of its surface, and the volume of deeper structures. The links were strongest in young women. They were weaker in men and in children. This is the largest study of its kind, and it included people from around the world.
Professor Tiffany Ho of UCLA is the senior author of the paper, which appears in the journal Biological Psychiatry. She explained that childhood mistreatment is a major risk factor for stress-related illnesses, including depression and post-traumatic stress disorder. The team wanted to know if these painful experiences have a lasting impact on the brain.
Earlier studies mostly looked at the combined effect of many harmful events. This team took a different view. A child’s brain is still forming its main networks, so it reacts strongly to the world around it. Scientists call this heightened plasticity. Because of this, harm at an early age could shape the brain more than harm later in life. The researchers suspected that the timing of abuse would matter.
Haley Wang, now a postdoctoral fellow in UCLA Psychiatry, worked with an international group called the ENIGMA Consortium. Together they reviewed brain scans from 1,389 people with PTSD or major depression. They also reviewed scans from 2,322 healthy volunteers. The scans came from eight countries.
Each person filled out a standard questionnaire about their childhood. It asked about physical abuse, emotional abuse, sexual abuse, physical neglect, and emotional neglect. Participants answered by looking back on their past. From the answers, the team built two scores. One showed how severe the abuse was overall. The other showed how severe the neglect was. Neglect was scored separately so its effects would not be mixed up with those of trauma.
The scans measured the thickness of the cortex, which is the outer layer of the brain. They also measured the volume of the subcortex, the deeper layers, and the total surface area.
To judge what was normal, the researchers used a reference tool built from years of brain data. It works like a growth chart for the brain. It shows how the brain usually changes with age. People with high maltreatment scores showed a clear but uneven set of differences from this chart. This suggests that adversity changed the path along which these brain areas developed.
Severe abuse was linked to a larger thalamus and pallidum than expected for a person’s age. It was also linked to a smaller isthmus cingulate cortex and a bigger surface area in the medial orbitofrontal cortex. These changes were clearest in young women. Older women still exhibited many of the same patterns.
Wang and Ho offered two possible reasons for the stronger effects in women. Girls face sexual trauma more often than boys during this sensitive stage. Alternatively, female brains may respond more intensely to trauma. More research is needed to know for sure.
Neglect showed narrower effects. In young women, it changed the surface area mainly in the cingulate regions, near the middle of the brain. In young men, it was tied only to a smaller right middle temporal cortex.
Wang noted that the cortex was split into more than 70 regions, and they did not all behave alike. Some areas were thinner, some thicker, some larger, and some smaller. The results indicate that childhood trauma has no single fixed effect. They reveal nothing about abilities. NIH helped fund the work.
