A study in South Korea found that people who survived childhood sexual abuse and currently suffer from major depression disorder had significantly lower gray matter volume in the right middle occipital gyrus region of the brain. Their grey matter volume in this specific region was lower than both healthy adults and people suffering from depression who did not experience sexual abuse in childhood. The study was published in Psychiatry Research.
Abuse in childhood has been shown to be associated with a number of negative outcomes in adulthood. These include negative perceptions of oneself, easily losing one’s temper, verbal aggression, drug and alcohol abuse, sexual misconduct, and many other issues.
Research has shown that childhood abuse also makes a person more vulnerable to a broad range of psychiatric disorders that include major depressive disorder (depression), post-traumatic stress disorder, borderline personality disorder, and panic disorders. Depending on the type of abuse experienced, researchers found between 1.5 and more than 3 times higher risk of depression in individuals who suffered abuse as children.
However, the neurobiological mechanisms responsible for this increase in vulnerability are currently unknown. Existing studies have linked depression with reduced grey matter volume in the brain, but few studies investigated structural abnormalities of the brain related to childhood abuse.
Study author Soo Young Kim and her colleagues hypothesized that different type of childhood abuse would also be associated with a decrease in gray matter volume in the brain regardless of whether the person suffers from depression or not. They also expected that even in patients suffering from depression, a history of a specific type of childhood abuse would be associated with a decrease in the volume of gray matter.
For their study, the researchers recruited 75 persons suffering from depression and 97 healthy participants. This took place between May 2019 and February 2021. All participants suffering from depression were patients of the outpatient psychiatric clinic of Korea University Anam Hospital in Seoul. Healthy participants were recruited using advertisements from the local community. All participants were right-handed. The average age of participants was around 37 years.
Participants from both groups completed assessments of the severity of depressive symptoms and of childhood trauma. The childhood trauma assessment assessed three types of abuse (sexual, physical, and emotional) along with physical and emotional neglect. In this study, the researchers focused on the three types of abuse. Based on the results of this assessment, the participants were further divided into “childhood abuse” and “non-abuse” groups. Participants also underwent magnetic resonance imaging.
Results showed that participants suffering from depression had lower grey matter volume in the anterior cingulate gyrus, left short insular gyrus, and right pars triangularis regions of the brain compared to healthy participants.
Participants who experienced childhood sexual abuse showed a significantly smaller cortical gray matter volume in the right middle occipital gyrus, right pars orbitalis, left superior parietal lobule and left pars triangularis regions of the brain compared to participants who did not experience childhood sexual abuse (in the total sample). No cortical regions of participants who experienced childhood sexual abuse had higher gray matter volumes compared to participants who did not experience abuse.
Results also showed that higher scores on the childhood sexual abuse assessment were related to lower sizes of the middle occipital gyrus region of the brain. This association was not present in survivors of other types of abuse.
“Our results suggest that exposure to childhood sexual abuse is related to a significant decrease in the cortical volume of the right middle occipital gyrus – which corresponds to a visual cortex – in a group of adult patients with major depressive disorder and healthy participants,” the study authors wrote. “We also compared patients who experienced childhood physical abuse or childhood emotional abuse with those who did not; however, no significant differences were found in cortical volumes.
“Moreover, we observed a reduced volume in the right anterior cingulate gyrus in patients with major depressive disorder compared to that in healthy participants,” they continued. “While childhood sexual abuse and major depressive disorder affected the cortical volume of the right middle occipital gyrus and anterior cingulate gyrus, respectively, post-hoc analyses showed that even patients in the major depressive disorder group who were exposed to childhood sexual abuse showed a pronounced decrease in the right middle occipital gyrus volume.”
The study contributes to the knowledge about neurobiological underpinnings of relations between adverse childhood experiences and later outcomes. However, it also has limitations that need to be taken into account. Notably, in some comparisons, groups of participants were too small for differences of the observed size to be detectable using statistical procedures applied. Additionally, the study design does not allow any cause-and-effect conclusions to be made about the observed associations.
The study, “Childhood abuse and cortical gray matter volume in patients with major depressive disorder”, was authored by Soo Young Kim, Seong Joon An, Jong Hee Han, Youbin Kang, Eun Bit Bae, WooSuk Tae, Byung-Joo Ham, and Kyu-Man Han.
