The effects of clozapine on tardive dyskinesia

Article Abstract:

Tardive dyskinesia is repetitive involuntary movements, which can affect the trunk and limbs, but primarily involves the facial muscles; this is a common side effect of prolonged treatment with neuroleptic, or antipsychotic medication. In spite of the attention that this side effect has received, the majority of those suffering from tardive dyskinesia develop only mild, nondistressing symptoms. In more severe cases, symptoms can be life-threatening. While the vast majority of neuroleptics have been associated with the development of tardive dyskinesia, clozapine has not. Clozapine has a different physiological mechanism than traditional neuroleptics, which may explain why the side effect is not present. Research has also suggested that clozapine may be effective in relieving tardive dyskinesia caused by the classic neuroleptics. A treatment protocol was designed for patients who were resistant or intolerant to standard antipsychotic medication. Clozapine was administered to 58 patients; at six weeks patient progress was evaluated to determine if treatment with clozapine should be continued. Evaluations for tardive dyskinesia were performed at 12-week intervals. Of the 58 patients who began the study, 21 discontinued because of noncompliance, side effects, or because of lack of therapeutic response. Of the 37 patients who received clozapine for at least 12 weeks, 13 had symptoms of severe tardive dyskinesia at the study's outset. Approximately 43 percent of those with tardive dyskinesia had a decrease in symptoms; patients with the most severe symptoms showed the greatest improvements. Results were variable, however, making definitive conclusions impossible; further research is needed. (Consumer Summary produced by Reliance Medical Information, Inc.)

Drugs, Testing, Physiological aspects, Clozapine

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The prediction of chronic persistent versus intermittent tardive dyskinesia: a retrospective follow-up study

Article Abstract:

Tardive dyskinesia (TD) refers to the involuntary movements seen in patients who are given neuroleptic (antipsychotic) medications over a period of time. This side effect presents a particular problem because many of the afflicted patients need continued treatment of ongoing psychiatric disorders, but continued treatment may increase the severity of the side effects. TD is not always persistent, however, and some studies have shown that it does not get progressively worse over time, but these studies have used small numbers of subjects or have studied them over too short a time to draw definitive conclusions. In the present investigation 192 TD patients were studied for an average of 7.7 quarterly visits. Subjects were psychiatrically evaluated, severity of involuntary movement was measured, and the natural history of TD was observed. Demographic information was obtained as well. Using statistical analysis to identify which demographic and clinical variables were associated with chronic persistence of TD, being older and the presence of TD affecting areas beside the face were seen to be significant factors. An age increase of 20 years was associated with 1.8-fold increase in the likelihood of chronic persistent TD, and the presence of nonfacial involuntary movements were associated with a 2.7 times greater likelihood of chronicity. Interestingly, ill-fitting dentures arose as a significant predictor as well. This study provides useful information regarding outcome patterns in TD patients who must continue to take neuroleptic medication, although the patterns are not yet definitive. (Consumer Summary produced by Reliance Medical Information, Inc.)

Risk factors, Psychotropic drugs

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Predictors of improvement in tardive dyskinesia following discontinuation of neuroleptic medication

Article Abstract:

Tardive dyskinesia (TD), a condition induced by the long-term use of neuroleptic (antipsychotic) drugs, results in impaired and involuntary body movements which persist long after withdrawal of the neuroleptic. To measure TD outcome, monthly multiple assessments were carried out among 49 chronic psychiatric outpatients (15 males and 34 females) who were followed-up for an average of 40 weeks after discontinuation of neuroleptics. The average age of the patients was 54 years, and average neuroleptic exposure was about nine years. Ten of the patients were schizophrenic, and the remainder had an assortment of diagnoses including bipolar (manic depressive) and schizoaffective disorders. Only two percent of the patients demonstrated a total reversal of TD symptoms. Patients who were able to stay off neuroleptic medication for 24 weeks showed about a 50 percent reduction in TD symptoms. However, many of the improved patients became psychotic and had to be placed on neuroleptics again. Employed patients demonstrated significantly more improvement than unemployed patients. Two puzzling findings were that patients with the longest illness duration demonstrated significantly more improvement than younger patients with shorter illness duration, and that higher neuroleptic doses before discontinuation were predictive of greater improvement. Nonschizophrenic patients were 3.3 times more likely to improve than schizophrenic patients or patients with other diagnoses, suggesting that both type and longevity of psychiatric illness affect TD outcome. (Consumer Summary produced by Reliance Medical Information, Inc.)

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