In healthy humans, the brain shows typical differences between the left and the right hemisphere in structure and function – so-called hemispheric asymmetries. In different psychiatric and neurodevelopmental disorders like schizophrenia, autism spectrum disorder, dyslexia, depression and posttraumatic stress disorder however, many asymmetries are reduced. Most of these disorders show a small genetic overlap with each other but none with asymmetry-related genes. A common non-genetic factor among these disorders are changes in the stress system as well as intra- and early life stress. A team from the Biopsychology and the Cognitive Psychology lab from the Ruhr University Bochum now propose a model in which early life stress as well as chronic stress not only increases the risk for psychiatric and neurodevelopmental disorders but also changes structural and functional hemispheric asymmetries. This influence might arise from prenatal effects of maternal stress and early life stress on the stress system and disease development: maternal adversity influences the environment in the womb which in turn programs neural systems underlying cognitive-emotional function. This could also be the case for the development of hemispheric asymmetries. Moreover, pathological changes in the stress system as well as hemispheric asymmetries may lead to further dysregulation in the brain. However, the effect of stress on hemispheric asymmetries could depend on the timing and type of the stressor.

Berretz, G., Wolf, O. T., Güntürkün, & Ocklenburg, S. (2020). Special Issue "Brain and cognitive asymmetry": Review. Atypical lateralization in neurodevelopmental and psychatric disorders: What is the role of stress? .