The use of computed tomography in psychiatry: Recent applications to schizophrenia, manic-depressive illness and dementia syndromes

The technique of CT scanning used in psychiatry has led to a number of important discoveries. The first such finding is that the syndrome of schizophrenia has, in a subgroup of those chronically affected, pathological correlates in the form of several types of cerebral atrophy. Because prospective and follow-up studies have not yet been published, it is unclear when these changes have their onset, and whether they are progressive or reversible. Neuropathologic studies, especially those using cytoarchitectonics, will help elucidate the nature of the abnormality associated with each atrophic subtype. In manic-depressive illness, parallel work needs to be done in the correlation of neurophysiological and psychological variables with neuroradiological subtypes. In neuropsychiatric illness, the correlation of signs and symptoms with localized density changes shown on CT scan provides a useful means of studying brain-behavior relationships. In dementia, a syndrome of diverse etiologies, the use of numerical data is both an aid to differential diagnosis, and a means of following the natural history of the disease. Although the relationship of changes in CT density numbers to neuropathology in dementias remains to be clarified, one potentially useful application of this information could be pre-symptomatic diagnosis in at-risk patients with Huntington's disease.