A research in South Korea found that individuals who survived childhood sexual abuse but are now suffering from major depression disorder had significantly lower gray matter volumes in the right middle occipital gyrus region of the brain. Both healthy individuals and people suffering from depression who did not experience sexual abuse in childhood did not suffer from this condition.
Abuse in childhood has been linked to a number of unpleasant outcomes in adulthood, including poor self-esteem, excessive alcohol abuse, and many more.
Researchers have found that childhood neglect increases a person's risk of a wide spectrum of psychiatric disorders, including major depressive disorder (depression), post-traumatic stress disorder, borderline personality disorder, and panic disorders.
However, the neurobiological mechanisms responsible for this increase in vulnerability are still unknown. Existing studies have linked depression to decreased grey matter volume in the brain, but few studies investigated structural abnormalities related to childhood abuse.
Soo Young Kim and her colleagues hypothesized that a different kind of childhood exploitation will be linked to a decrease in gray matter volume in the brain regardless of whether or not the individual suffers from depression. They also assumed that a history of a specific type of childhood abuse would be linked to a decrease in gray matter volume in the patient's brain.
The researchers recruited 75 individuals suffering from depression and 97 healthy participants for their research. All participants suffering from depression were patients of the Korea University Anam Hospital in Seoul's outpatient psychiatric clinic. Healthy participants were recruited using local advertisements.
Participants from both groups completed assessments of the severity of depressive symptoms and of childhood trauma. Three types of abuse (sexual, physical, and emotional) were assessed in this study, along with physical and emotional neglect.
In comparison to healthy participants, participants with depression showed a decrease in grey matter volume in the anterior cingulate gyrus, left short insular gyrus, and right pars triangularis regions of the brain.
In contrast to participants who did not experience childhood sexual abuse, no cortical regions had higher gray matter volumes than those who did not experience abuse.
Higher scores on the childhood sexual abuse assessment were linked to smaller brain areas in the middle occipital gyrus region, unlike in other types of abuse.
According to the authors, childhood physical 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. "We also compared patients who experienced childhood physical abuse or emotional abuse with those who did not, and no significant differences were found in cortical volumes."
“In patients with major depressive disorder, we observed a decrease in the right anterior cingulate gyrus, compared to that in healthy individuals,” said the authors. “While childhood sexual abuse and major depressive disorder affected the cortical volume of the right middle occipital gyrus, post-hoc analyses showed that even children exposed to childhood sexual abuse saw a significant decrease in the right middle occipital gyrus,” said the authors.
The research advances our understanding of neurobiological connections between unpleasant childhood experiences and subsequent outcomes. Nonetheless, it does have limitations that must be addressed. For instance, in some surveys, groups of participants were too small for differences of the observed size to be detectable using statistical techniques applied.
Soo Young Kim, Seong Joon An, Jong Hee Han, Eun Bit Bae, WooSuk Tae, Byung-Joo Ham, and Kyu-Man Han co-authored the study titled "Childhood abuse and cortical gray matter volume in patients with major depressive disorder."