Is there a tardive dysmentia?

Antipsychotic-induced supersensitivity - A reappraisal

OBJECTIVES

Tardive dyskinesia, psychotic relapse and treatment-refractory psychosis have long been associated. A common underlying mechanism involving antipsychotic-induced 'supersensitivity', albeit in different brain pathways, was proposed as early as 1978. This piece seeks to reappraise the concept and potential implications of antipsychotic-induced supersensitivity.

CONCLUSIONS

Evidence increasingly suggests that chronic antipsychotic exposure induces neuroadaptive physiological changes in dopaminergic, and other, neurotransmitter systems that may render some individuals more vulnerable to psychotic relapse - including those receiving continuous antipsychotic treatment. It is possible that in treating every episode of psychosis with prolonged or indefinite antipsychotic therapy, we paradoxically increase the risk of psychotic relapse in a significant proportion of people. A greater appreciation of supersensitivity may allow us to optimise any potential benefits of antipsychotics while minimising the risk of inadvertent iatrogenic harms. More research is needed to improve our understanding of the underlying neurophysiology of supersensitivity and to better identify which individuals are most vulnerable to its development. It is time we paid more attention to the concept, emerging evidence and potential implications of antipsychotic-induced supersensitivity and, where appropriate, adjusted our practice accordingly.

Mood and emotional disorders associated with parkinsonism, Huntington disease, and other movement disorders

This chapter provides a review of mood, emotional disorders, and emotion processing deficits associated with diseases that cause movement disorders, including Parkinson's disease, Lewy body dementia, multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration, frontotemporal dementia with parkinsonism, Huntington's disease, essential tremor, dystonia, and tardive dyskinesia. For each disorder, a clinical description of the common signs and symptoms, disease progression, and epidemiology is provided. Then the mood and emotional disorders associated with each of these diseases are described and discussed in terms of clinical presentation, incidence, prevalence, and alterations in quality of life. Alterations of emotion communication, such as affective speech prosody and facial emotional expression, associated with these disorders are also discussed. In addition, if applicable, deficits in gestural and lexical/verbal emotion are reviewed. Throughout the chapter, the relationships among mood and emotional disorders, alterations of emotional experiences, social communication, and quality of life, as well as treatment, are emphasized.

The current status of tardive dyskinesia

OBJECTIVE

This paper aims to provide an overview of the current knowledge on neuroleptic-induced tardive dyskinesia (TD) in relation to its clinical features, risk factors, pathophysiology and management.

METHOD

The published literature was selectively reviewed and assessed.

RESULTS

Tardive diskinesia is a common neurological side-effect of neuroleptic medication, the cumulative incidence of which increases with increasing duration of treatment. Its clinical manifestations are diverse and subsyndromes have been described. Many risk factors for TD are now recognised, but increasing age remains pre-eminent as a risk factor. The pathophysiology of TD is not completely understood. Of the neurotransmitter hypotheses, the dopamine receptor supersensitivity hypothesis and the gamma-aminobutyric acid insufficiency hypothesis are the main contenders. There is increasing recognition that TD may in fact be caused by neuroleptic-induced neuronal toxicity through free radical and excitotoxic mechanisms. The occurrence of spontaneous dyskinesias in schizophrenic patients and even healthy subjects suggests that neuroleptics act on a substratum of vulnerability to dyskinesia. As no effective treatment for TD is available, the primary emphasis is on prevention. Many drugs can be tried to reduce symptoms in established cases. The increasing use of atypical neuroleptics has raised the possibility of a lower incidence of TD in the future.

CONCLUSIONS

After four decades of clinical recognition, the pathophysiology of TD is still not understood and no effective treatment is available. Its prevention with the optimal usage of currently available drugs and regular monitoring of patients on long-term neuroleptic treatment remain the best strategies to reduce its impact.

Free radical mechanisms in schizophrenia and tardive dyskinesia

The present article discusses the distribution of free radical processes in the central nervous system (CNS). Specifically, we discuss the involvement of oxyradicals in the normal metabolism of catecholamine. We also review some proposals related to the possible importance of these compounds in the development of neuropsychiatric and movement disorders such as schizophrenia and neuroleptic-induced tardive dyskinesia (TD), respectively. Clinical studies have shown that antioxidant treatment can attenuate the movement abnormalities observed in TD. Further studies are necessary to evaluate the status of specific scavenging systems in these two disorders. The prophylactic use of antioxidants in patients who are treated with neuroleptics needs also to be considered.

Loss of striatal cholinergic neurons as a basis for tardive and L-dopa-induced dyskinesias, neuroleptic-induced supersensitivity psychosis and refractory schizophrenia

In the first section of this paper several aspects of tardive dyskinesia (TD) (clinical, epidemiological, pharmacological) are reviewed. We propose that this syndrome is not the consequence of dopamine receptor proliferation, but results from damage or degeneration of striatal cholinergic interneurons. We suggest that this cellular damage is caused by prolonged overactivation of these neurons, which occurs when they are released from dopaminergic inhibition following neuroleptic administration. Overactivity of central cholinergic systems during akinetic and motor retarded depression could be a contributory cause. The predisposition to L-DOPA-induced peak-dose dyskinesia in Parkinson's disease may depend on the same type of striatal neuronal loss. In the second part of the paper, the subject of supersensitivity psychosis and drug-resistant schizophrenia is reviewed. These two syndromes, are commonly associated with TD, have similar predisposing factors and pharmacology to TD, and are potentially persistent. We suggest that these conditions also result from degeneration of cholinergic striatal interneurons following chronic neuroleptic administration. The efficacy of clozapine for such treatment-refractory psychoses is explained in terms of its blockade of D-1 dopamine receptors. Other drugs effective against refractory psychoses (e.g. risperidone) are predicted to reduce activation at D-1 receptors.

Late-onset schizophrenia: relationship to awareness of abnormal involuntary movements and tobacco addiction

Although schizophrenia usually emerges at mid to late-adolescence, it has been estimated that almost 20% of schizophrenic patients develop their first symptoms in mid to late life (late-onset schizophrenia). The biological characteristics that distinguish patients with early onset from those with late-onset schizophrenia have not been well delineated. A subgroup of neuroleptic-treated schizophrenic patients develops tardive dyskinesia (TD) and the majority of these patients are unaware of their movements. To investigate whether early and late-onset schizophrenic patients with TD could be differentiated on the basis of awareness of involuntary movements, we compared the prevalence of awareness of these abnormal movements in patients with early (N = 40) and late-onset (N = 15) schizophrenia. We found a significantly higher prevalence of awareness of involuntary movements in patients with late-onset schizophrenia as compared to those with an earlier age of onset (86.6% vs. 25.0%, p < .0001). In a second study, we investigated whether early and late-onset schizophrenia could be differentiated on the basis of dopamine functions in the mesolimbic system. Since tobacco addiction is mediated via limbic dopaminergic functions, we investigated the prevalence of tobacco addiction in patients with early (N = 51) and late-onset (N = 13) schizophrenia. We found a significantly lower prevalence of tobacco addiction in patients with late-onset schizophrenia as compared to those with an earlier age of onset (15.4% vs. 54.9%; X2 = 6.49; p < .01). Our findings support the notion that distinct pathophysiological mechanisms underlie the development of early and late-onset schizophrenia.

Subjective awareness of abnormal involuntary movements in schizophrenia

A wide majority of schizophrenic patients with Tardive dyskinesia, a neurological disorder produced by chronic neuroleptic therapy, lack awareness of their involuntary movements. This by contrast to patients with Parkinsonism who usually are aware of their abnormal movements. In the following communication we present a series of studies which are aimed at providing further insight into the issue of awareness of involuntary movements in schizophrenic patients with tardive dyskinesia. In addition, we investigated whether edentulosness, which may be a risk factor for orofacial dyskinesias in the elderly, is also a risk factor for neuroleptic-induced orofacial dyskinesias. We found that: (a) one's awareness of involuntary movements is related to some but not all muscle groups, (b) tardive dyskinesia may be associated with a significant distress, (c) lack of awareness may be a feature of frontal lobe dysfunction in schizophrenia, (d) patients who lack awareness of their involuntary movements have a higher prevalence of pineal calcification, and (e) edentulosness, which is related to deficits in the orofacial sensorimotor system, increases the risk for neuroleptic-induced orofacial dyskinesias.

Facial dyskinesia: a 16-year follow-up study

The 109 female survivors of a mental hospital population surveyed in 1965 for facial dyskinesia were followed up 16 years later. The 99 survivors with non-organic brain syndromes were analysed. Prevalence of dyskinesia had risen from 18.4% to 46.5% during follow-up and its development was significantly associated with neuroleptic dosage. Enlarged ventricles on brain scans were significantly associated with dyskinesia, cognitive impairment and neuroleptic prescribing.

Regional brain glucose metabolism in drug free schizophrenic patients and clinical correlates

Regional brain glucose metabolism was investigated in healthy volunteers (n = 10) and in drug free schizophrenic patients (n = 20). The metabolism was determined by positron emission tomography (PET) with 11C-glucose as the tracer. Diagnosis of schizophrenia was made according to RDC and DSM III. Eight patients had their first psychotic episode, four patients had a subchronic course and eight patients had a chronic course with an exacerbation of their illness. Computed tomography (CT) of the brain were made in all the subjects. Regions of interest (n = 35) were drawn on displayed CT images and the marked regions were transferred to the corresponding slice of the PET examination. The PET investigation was made in a dimly lit, quiet room with the eyes of the subject covered. The time course of the 11C-glucose uptake was measured by a four ring PET scanner (PC-384-7B). Metabolic rates of glucose varied greatly among the schizophrenic patients investigated. The variance was significantly greater than that of the controls in most regions. Decreases in mean levels of metabolic rates were related to patients with subchronic or chronic courses. Changes in metabolism were not related to previous duration of neuroleptic treatment of the patients. Left-right asymmetries were found in the temporal lobe (area 22) and the basal frontal cortex (area 11), the metabolic rates of the patients being lower on the left side compared to the controls. Asymmetry of the metabolic rate of the amygdala in hebephrenic patients was the opposite of that found in paranoid patients and controls. Negative correlations between regional metabolic rates and autistic or negative symptoms were found. Thus, the lower the metabolic rate was, the more autistic the patient. Metabolic rates were not correlated to atrophic changes of the brain. No basis for a specific alteration in frontal cortical metabolism of schizophrenics was obtained. Changes in regional metabolic rates in schizophrenia are suggested to reflect disturbances in more general mechanisms which are of importance in neuronal function.