Parental verbal abuse (paVA) experience can affect the developmental trajectory of the brain, and may be one of avoidable causes of psychiatric disorders. Previous researches reported a relationship between paVA and brain regions associated with emotional processing, such as cingulate, hippocampus and amygdala. However, little research has been done on neurochemical changes, and recent studies have shown that verbal abuse is not simply a brain damage, but an adaptive change associated with neuroplasticity. In this study, 1) I investigated the effect of paVA on neurochemical properties and connectivity of the brain, and generate model which predicts the perceived intensity of paVA abuse using MRS and diffusion tractogrpahy. 2) Using functional MRS (fMRS) and emotional stroop task, I investigated relationship between perceived intensity of paVA and change in glutamate response to swearing word, and relationship between the change and psychiatric symptoms to identify structural-neurochemical linkage between psychiatric symptoms and paVA. For this purpose, I focused on limbic system, one of the key region for emotional processing. PaVA was positively associated with threat detection circuit, and negatively associated with reward circuit. Further PaVA was related to decrease in myo-inositol concentration, which represents altered glial function.
The partial least square regression model with cross validation showed that individual variance of perceived paVA was associated with chemical properties and structural connectivity of pregenual anterior cingulate cortex (pgACC), regulatory region of limbic system. The fMRS analysis revealed particular association between paVA and glutamate response to swearing word. Furthermore variance of psychiatric symptoms such as trait anxiety, state anxiety and depressive symptoms could be marginally explained by the interaction term of the glutamate response and baseline N-acetyl aspartate concentration.
To summarize, I found the association of paVA with anatomical connectivity and neurochemical properties of limbic system. This study may that structural and functional change of reward circuit and emotional processing may occur in proportion to intensity of paVA, even if they are not enough to cause psychiatric disease, and may contribute to the manifestation of subclinical psychiatric symptoms.