NEUROIMAGING STUDIES OF SCHIZOPHRENIA

Neuroimaging studies of schizophrenia have identified abnormalities in neuroanatomy, regional brain metabolism and receptor physiology. Computerized tomographic (CT) studies have demonstrated gross ventricular and sulcal enlargement. These findings are probably nonprogressive, and it is not yet clear whether they are present only in a subgroup of patients; whether they represent a reduction in tissue from a previously normal condition or an abnormality in brain development; and what relationship they have to genetic risk for schizophrenia, clinical features, or longterm prognosis. Magnetic resonance imaging (MRI) studies, which offer higher resolution and greater flexibility in imaging plane, are currently focussing on specific neuroanatomic sites, such as the limbic system, basal ganglia and frontal cortex, implicated by neuropathological or clinical studies in the pathophysiology of schizophrenia. Positron emission tomographic (PET) scanning now enables investigators to study brain metabolism and receptor physiology. Evidence to date suggests that there may be significant abnormalities in the pattern of cerebral glucose utilization as well as in the density of dopamine receptors in patients with schizophrenia. Much future work is needed to determine the sensitivity and specificity of these observations as well as the extent to which they are affected by changes in clinical state, attention and medication exposure.