Schizophrenia and hemispheric brain functioning : a neuropsychological case study of a monozygotic twin case.

Abstract

Schizophrenia is a debilitating mental illness which is complex and multifactorial in nature. Currently a full understanding of the exact aetiological and treatment pathways is yet to be understood, with effective treatment of the debilitating and pervasive negative symptoms particularly lacking. However recent advances in neurophysiological and neuropsychological research seem to be converging on theories of the central role of lateralised functional systems. These models implicate right hemispheric hyperactivation in negative symptom patterns, while positive symptoms are thought to be associated with left frontal hypoactivation resulting in compensatory left temporal hyperactivation. Through the use of the Cognitive Neuropsychological case study methodology, this research took an inductive and exploratory approach to a unique case of 41 year old monozygotic twins concordant for schizophrenia and discordant for a right frontal cerebrovascular accident (CVA). From various records the CVA seemingly had a positive effect on the affected-twin's negative symptoms. By means of a selected battery of neuropsychological tests this research focused on patterns of test performance for known functional systems and identified neuropsychological correlates of the CVA and the negative symptom improvement. Statistically significant differences were found between the twins, particularly in the right medial and ventral prefrontal areas. These areas, with their projections to the limbic system and other sub-cortical structures, were highlighted as being important to these differences. From these findings working hypotheses regarding specific lobal structures, relating to existing theories and research in schizophrenia, were posited for future research.