Multivariate analysis of monoamine indices in patients with chronic schizophrenia

Levels of dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), noradrenaline (NA), 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid and serum levels of prolactin (PRL) and dopamine-beta-hydroxylase (DBH) were measured in 42 chronic schizophrenic inpatients grouped according to their scores on the Brief Psychiatric Rating Scale (BPRS) and the Abnormal Involuntary Movement Scale (AIMS). Factor analysis was carried out on various combinations of variables. In patients with tardive dyskinesia (TD), cerebrospinal fluid DA, DOPAC, HVA, NA, and serum DBH were distributed into three factors; in patients without TD, these substances were assembled in only one factor. Cerebrospinal fluid DA, DOPAC, and HVA were dispersed in two factors in patients with severe positive symptoms versus one factor in subjects with mild productive signs. Factor structures diverged only when the variables listed above were included in the analysis. These findings support the hypothesis that both the dopaminergic and the noradrenergic system contribute to TD and that positive schizophrenic symptoms are associated with dopaminergic dysregulation.