SCHIZOPHRENIA - A BRAIN DISEASE - A CRITICAL-REVIEW OF STRUCTURAL ANDFUNCTIONAL CEREBRAL ABNORMALITY IN THE DISORDER

Background. With genetic and neurochemical findings pointing to a biol ogical aetiology, considerable effort has been devoted to finding dire ct evidence of brain abnormality in schizophrenia. Method. CT, MRI, po st-mortem and functional imaging studies are reviewed to assess which structural and/or functional brain abnormalities have been consistentl y demonstrated. Results. The only well-established structural abnormal ity in schizophrenia is lateral ventricular enlargement; this is modes t and there is a large overlap with the normal population. There is no consensus on the presence of any localised structural abnormality fro m MRI and postmortem studies, but the most promising findings concern temporal lobe limbic structures. Hypofrontality is not a well-replicat ed finding in schizophrenia under resting conditions, but the evidence is stronger for a selective association with negative symptoms. A num ber of studies have found hypofrontality under conditions of neuropsyc hological task activation. However, findings in these studies are divi ded and a recent methodologically sophisticated study has failed to co nfirm it, although this study suggested a decoupling of prefrontal and temporal function. Conclusion. Schizophrenia is characterised by mino r structural abnormality which, in the case of lateral ventricular enl argement, may be better understood as a risk factor than a causative l esion. The functional imaging findings are not transparent but suggest that, as a disorder, schizophrenia shows complex alterations in regio nal patterns of activity rather than any simple deficit in prefrontal function.