Reduced activity of angiotensin-converting enzyme in basal ganglia in early onset schizophrenia

Abstract

The dipeptidyl peptidase, angiotensin-converting enzyme (EC 3.4.15.1), was measured in various regions of post-mortem brains. Results from 51 patients with the hospital diagnosis of schizophrenia who were divided into the clinical categories of ‘schizophrenia’ and ‘schizophrenialike’ illness on the basis of case-note analysis were compared with those from 40 control subjects. A significant reduction in angiotensin-converting enzyme activity was observed only in the substantia nigra pars reticulata and in the lateral and medial segments of globus pallidus in the ‘schizophrenia’ group, with no significant differences in enzyme activity in substantia nigra pars compacta, caudate nucleus, nucleus accumbens, subthalamic nucleus or cerebellar cortex. Reduced enzyme activity was not seen in the ‘schizophrenia-like’ group, and occurred most significantly in ‘schizophrenia’ patients in whom the onset of the illness had occurred between the ages of 15 and 24 years. In the control population the activity of angiotensin-converting enzyme in substantia nigra pars reticulata decreased significantly with age. It is possible that patients with early onset ‘schizophrenia’ may represent a separate disease entity, rather than belonging to a spectrum of a single disease.