New neuroscience research published this week in the Proceedings of the National Academy of Sciences reports that male and female adolescents who reported maltreatment during childhood showed weaker connections between the hippocampus and the prefrontal cortex. In addition, the girls showed weaker connections between the amygdala and the prefrontal cortex. Put simply, the amygdala is the site of fear reactions, the hippocampus governs memory, and the prefrontal cortex is responsible for rational thought and regulating emotions.
“Weaker connections between the prefrontal cortex and the amygdala and hippocampus may cause teenagers to have difficulty judging, based on past situations, whether a situation is safe or not, as well as an exaggerated fear response,” says lead author Dr. Ryan Herringa, assistant professor of child and adolescent psychiatry at the University of Wisconsin School of Medicine and Public Health.
“This could put maltreated youth at risk for developing mental illness such as anxiety, depression, and post-traumatic stress disorder. In addition, the double hit on the fear circuitry associated with early maltreatment in girls may help to explain why they are more likely to experience depression and anxiety.”
Herringa said the results are more striking because the adolescents are part of a long-running community study in which maltreatment did not often rise to the level of reportable child abuse. Instead, it includes more normative child experiences such as emotional neglect as well as abuse, physical neglect, and harsh parenting.
The 64 adolescents in the study came from the long-running Wisconsin Study of Families and Work (WSFW). In 1990 and 1991, 570 newborns and their families, all of them born in the Madison or Milwaukee areas, were enrolled by Dr. Marilyn Essex, a UW professor of psychiatry and Dr. Janet Hyde, a UW professor of psychology, co-directors of the WSFW. In collaboration with Dr. Richard Davidson, a UW professor of psychiatry and psychology, Dr. Essex began collecting brain imaging on subsets of this sample when they were age 15. Over the years, the study has resulted in important findings on the social, psychological, and biological risk factors for child and adolescent mental health problems.
In the current study, 64 18-year-olds underwent resting-state functional connectivity (fcMRI), which looks at the brain connections while the brain is at rest.
“Maltreatment experiences were associated with weaker connections between the hippocampus and the frontal cortex in both boys and girls, but with weaker connections between the amygdala and prefrontal cortex in girls only. This suggests that girls may be more vulnerable to these levels of maltreatment,” Herringa says.
The research also correlated the adolescents’ reports of childhood maltreatment experiences with responses their mothers made to a stress survey when the children were younger. Mothers who reported “negative parenting,” such as feeling angry towards their child or often having conflict with them, had children who later reported more childhood maltreatment experiences when asked as teenagers. This provides some evidence that the maltreatment memories of the teens were not simply due to their symptoms of depression and anxiety.
“The results from our study and many others make the case that, as a society, it is important to support the caregivers of children in stressed families,” says Herringa, who treats children and adolescents with PTSD. “Caregivers need help so they can help their children develop in a healthy way”
Collaborators on the paper are Dr. Rasmus Birn, Dr. Paula Ruttle and Essex, all of the department of psychiatry in the UW School of Medicine and Public Health; and Davidson, Dr. Cory Burghy, and Diane Stodola, all of the Waisman Laboratory for Brain Imaging and Behavior.
Their work was supported by US National Institutes of Health grants P50 MH084051, R01-MH044340 and P50-MH052354; the John D. and Catherine T. MacArthur Foundation Research Network on Psychopathology and Development; and the HealthEmotions Research Institute.
University of Wisconsin School of Medicine and Public Health