Tardive dyskinesia and plasma homovanillic acid

Using 61 patients with tardive dyskinesia (TD) and 25 normal controls, we explored the possibility that plasma HVA may reflect alterations in central dopamine activity or clinical aspects of TD. There were no significant differences between the two groups in plasma HVA level. Analyses of variance with age and sex as independent variables revealed that the major variance in plasma HVA was accounted for by age in both TD patients (p less than 0.001) and normals (p less than 0.049). Examining the TD patients alone, using multiple regression analysis, revealed that age, neuroleptic dose, and severity of TD accounted for 40% of the variance in plasma HVA in males, with age alone accounting for 28%. By comparison, females showed no association to neuroleptic dose or severity, and age only accounted for 8.9%. When severity of TD was the criterion variable, neuroleptic dose, plasma HVA, and age accounted for 20% of the variance in severity in female TD patients and showed no relationship in males. Possible implications of these differing findings in male and female TD patients are discussed.