Risperidone treatment of drug-related psychosis in patients with parkinsonism

Adverse reactions to antipsychotics in Parkinson disease: an analysis of the Spanish pharmacovigilance database

PURPOSE

Although antipsychotics are well known for causing a plethora of adverse drug reactions (ADRs), the main concern when used to treat psychosis in Parkinson disease (PD) has traditionally been motor function worsening. The limited number of patients included in clinical trials contributes to underreport less common ADR. The aims of this study were to describe ADR to antipsychotics occurring in patients with PD notified to the Spanish Pharmacovigilance System and to contrast them with published reports.

METHODS

All notifications from the Spanish Pharmacovigilance System for the last 30 years (1984-2014) where an antipsychotic was considered suspicious of the ADR in patients who were also on dopaminergic therapy were reviewed. In addition, a systematic search of MEDLINE (1966-2014) was conducted with the following Medical Subject Headings (MeSH) terms: "Parkinson disease" and "antipsychotic agents" or "psychotic disorders" and "drug-related side effects" or "adverse reactions."

RESULTS

Forty-four notifications were selected for evaluation. Quetiapine was the most frequently implicated drug since 2002, and previously clozapine was the drug implied in higher number of notifications. The most severe ADR was neuroleptic malignant syndrome, which was described in 5 patients (3 cases related to quetiapine, one to haloperidol, and another to olanzapine).

CONCLUSIONS

Some previously unreported ADRs caused by antipsychotic drugs in patients with PD have been described for the first time in this study, although there are in general well-known antipsychotic adverse effects. It is remarkable that some notifications involve the use of drugs not recommended in these patients.

[Parkinson's disease and psychoses]

Psychotic symptoms are common in Parkinson's disease (PD) and are associated with increased disability, worsened quality of life, and poor long-term prognosis. In this article, clinical features, hypotheses on pathogenesis, and current treatment strategies for Parkinson's disease psychosis (PDP) are reviewed. According to epidemiological studies, the prevalence of PDP is between 20 to 40 %. Complex visual hallucinations are the most common psychotic symptoms and are present in 17-72 % of the patients. Other sensory disturbances encompass tactile hallucinations and minor hallucinatory phenomena, such as sense of presence and visual illusions. Hallucinations are often accompanied by delusions, whose most frequent themes are persecution and jealousy. The pathophysiology of PDP remains unclear. Different factors have been implicated, including Levo-dopa and dopaminergic medications, neurotransmitter imbalances, neuroanatomic alterations, abnormal visuospatial processes, and genetic predisposition. The first-line strategy in the treatment of persistent and problematic PDP is represented by reduction in anti-PD medications. Second-generation antipsychotics are the treatment of choice, with clozapine being demonstrated as the most effective and tolerable drug for PD patients.

Summary of the recommendations of the EFNS/MDS-ES review on therapeutic management of Parkinson's disease

OBJECTIVE

To summarize the 2010 EFNS/MDS-ES evidence-based treatment recommendations for the management of Parkinson's disease (PD). This summary includes the treatment recommendations for early and late PD.

METHODS

For the 2010 publication, a literature search was undertaken for articles published up to September 2009. For this summary, an additional literature search was undertaken up to December 2010. Classification of scientific evidence and the rating of recommendations were made according to the EFNS guidance. In cases where there was insufficient scientific evidence, a consensus statement ('good practice point') is made.

RESULTS AND CONCLUSIONS

For each clinical indication, a list of therapeutic interventions is provided, including classification of evidence.

Psychiatric care in Parkinson's disease

OBJECTIVE

Parkinson's disease (PD) is a degenerative and disabling disease in which medical providers focus mainly on ameliorating problems in day-to-day functioning. This review summarizes current knowledge about the efficacy and tolerability of psychopharmacological agents in the treatment of depression, anxiety, psychosis, and insomnia in patients with PD. Recommended or promising nonpharmacological interventions are also reviewed.

METHOD

Studies were identified using computerized searches, with further references obtained from the bibliographies of the reviewed articles.

RESULT

Findings in the research literature provide growing evidence concerning the antidepressant treatment of patients with PD. Psychoeducational interventions for managing depression and anxiety symptoms also appear promising. Music therapy has proven to be particularly effective for patients with PD. Psychosis is common in patients with PD. When psychosis is induced by antiparkinson drugs, a dose reduction can be considered, but it is seldom successful. Patients with PD do not generally tolerate conventional antipsychotic medications, justifying evaluation of newer atypical agents in this population. Cholinesterase inhibitors have also become increasingly important in the treatment of PD in recent years. Finally, insomnia is a very frequent complaint in patients with PD and may also contribute to the development of depression. Patients should be encouraged to improve sleep hygiene and use behavioral interventions. Definitive trials of treatments for sleep disorders in this population are also warranted.

CONCLUSION

Therapeutic approaches to the treatment of PD and its associated psychiatric symptoms must be individualized and may involve a combination of antiparkinson drugs, psychopharmacological treatment, and/or psychotherapeutic interventions.

Nonmotor symptoms in Parkinson’s disease: the dark side of the moon

Nonmotor symptoms may appear during the course of Parkinson’s disease, complicating the advanced phase in particular, but are also common in the premotor phase of Parkinson’s disease. The appearance of nonmotor manifestations represents a milestone, determining a worse prognosis and lower quality of life; however, they are often misdiagnosed and untreated. The spectrum of nonmotor symptoms encompasses mood disorders, psychosis, dementia, sleep disorders, impulse-control disorders and autonomic dysfunctions. This article describes these nonmotor symptoms and their management.

Pharmacological management of psychosis in elderly patients with parkinsonism

Parkinsonism is a characteristic feature of Parkinson's disease and dementia with Lewy bodies and is commonly seen in Alzheimer's disease. Psychosis commonly appears during the course of these illnesses. Treatment of parkinsonism with antiparkinsonian medications constitutes an additional risk factor for the appearance or worsening of psychosis. Conversely, treatment of psychosis with antipsychotic drugs in patients with parkinsonism might worsen the underlying movement disorder, especially in the elderly. In this article, we review parkinsonian conditions in the elderly and offer guidelines to assess and manage comorbid psychosis. We focus on the pharmacologic management of psychosis with atypical antipsychotic medications and briefly review the role of acetylcholinesterase inhibitors.

The safety of dopamine agonists in the treatment of Parkinson's disease

Dopamine agonists are highly effective as adjunctive therapy to levodopa in advanced Parkinson's disease. These drugs have rapidly gained popularity as a monotherapy in the early stages of Parkinson's disease for patients < 65-70 years old, because they are about as effective as levodopa, but patients demonstrate a lower tendency to develop motor complications. However, dopamine agonists could have peripheral and central side effects, which are often the reason for the discontinuation of the treatment. This review focuses on the potential negative effects related to the use of dopamine agonists in the treatment of Parkinson's disease.

Course, prognosis, and management of psychosis in Parkinson's disease: are current treatments really effective?

It is essential to recognize and treat psychosis in Parkinson's disease for several reasons. Studies have shown that psychosis in Parkinson's disease patients is a strong risk factor for nursing home placement. Psychosis may be the greatest source of stress for caretakers of Parkinson's patients; it is often persistent, and its presence markedly increases mortality. Treatment of psychotic symptoms should occur only after potential medical and environmental causes of delirium have been eliminated or addressed. Initial pharmacologic changes should include limiting the patient's antiparkinsonian medications to those that are necessary to preserve motor function. Should that fail, an atypical antipsychotic is presently the treatment of choice. An emerging treatment option is acetylcholinesterase inhibitors. This article reviews what is currently known about the course, prognosis, and treatment strategies in Parkinson's disease psychosis.

New approaches to understanding hallucinations in Parkinson's disease: phenomenology and possible origins

The authors review current literature on hallucinations in Parkinson's disease (PD). Recent neuropathological studies showed that hallucinations occur in synucleinopathies and are a significant predictor of Lewy Body depositions. Therefore, hallucinations are a hallmark of PD and of dementia with Lewy Bodies. Visual hallucinations are mostly complex and kinematic; preserved or disturbed insight on the nature of hallucinations is a major prognostic factor, although eventually all hallucinators will present with reduced insight. Current theories on the origin of hallucinations point to visual dysfunction, dream overflow and cognitive impairment, yet objection can be raised on each one of the putative models of hallucinations. Understanding of the origin of hallucinations is required in order to develop treatments: all treatment evaluations were focused in general on psychosis, and only clozapine obtained positive evidence-based ratings on efficacy. However, it is likely that cholinesterase inhibitors, antipsychotics and anti-5-hydroxytryptamine(3) agents and drugs acting on sleep regulation will have different and perhaps opposite effects on different types of hallucinations, whether they are accompanied by disturbed insight, sleep disorders or other psychotic features. Further studies will try to separate phenomenology and responses to treatment and will investigate the relevance of concomitant sleep disorders and abnormality of frontoparietal networks involved in the attention process.

Drug-induced parkinsonism in the elderly

Drug-induced parkinsonism is primarily caused by drugs that interfere with dopamine stimulation. Antipsychotic drugs are the most common offenders, but drug-induced parkinsonism may be seen with many other drugs, such as antiemetics and certain calcium-channel blockers. These medications are widely used in the elderly. Unlike the first generation of antipsychotic drugs, all of which cause parkinsonism and other extrapyramidal side effects, atypical antipsychotics have motor side effects that are not uniform. Among the atypicals, only quetiapine and clozapine are not associated with drug-induced parkinsonism. Since drug-induced parkinsonism is frequently under-recognized, it may be devastating in an elderly person with already compromised gait.

Review of the therapeutic management of Parkinson's disease. Report of a joint task force of the European Federation of Neurological Societies (EFNS) and the Movement Disorder Society-European Section (MDS-ES). Part II: late (complicated) Parkinson's disease

To provide evidence-based recommendations for the management of late (complicated) Parkinson's disease (PD), based on a review of the literature. Complicated PD refers to patients suffering from the classical motor syndrome of PD along with other motor or non-motor complications, either disease-related (e.g. freezing) or treatment-related (e.g. dyskinesias or hallucinations). MEDLINE, Cochrane Library and INAHTA database literature searches were conducted. National guidelines were requested from all EFNS societies. Non-European guidelines were searched for using MEDLINE. Part II of the guidelines deals with treatment of motor and neuropsychiatric complications and autonomic disturbances. For each topic, a list of therapeutic interventions is provided, including classification of evidence. Following this, recommendations for management are given, alongside ratings of efficacy. Classifications of evidence and ratings of efficacy are made according to EFNS guidance. In cases where there is insufficient scientific evidence, a consensus statement ('good practice point') is made.

Cognitive deficits and psychosis in Parkinson's disease: a review of pathophysiology and therapeutic options

Parkinson's disease is a neurodegenerative disorder causing not only motor dysfunction but also cognitive, psychiatric, autonomic and sensory disturbances. Symptoms of dementia and psychosis are common: longitudinal studies suggest that up to 75% of patients with Parkinson's disease may eventually develop dementia, and the prevalence of hallucinations ranges from 16-17% in population-based surveys to 30-40% in hospital-based series. These cognitive and behavioural features are important in terms of prognosis, nursing home placement and mortality. The pattern of cognitive deficits in Parkinson's disease is variable, but often includes executive impairment similar to that seen in patients with frontal lesions, as well as episodic memory impairment, visuospatial dysfunction and impaired verbal fluency. The most common manifestation of psychosis in Parkinson's disease is visual hallucinations, but delusions, paranoid beliefs, agitation and florid psychosis can also occur. An understanding of the pathophysiology underlying these symptoms is essential to the development of targeted therapeutic strategies. Post-mortem studies suggest an association between Lewy body deposition and dementia in Parkinson's disease, and indeed Parkinson's disease and dementia with Lewy bodies may form part of the same disease spectrum. Whether Lewy bodies actually play a causative role in cognitive dysfunction, however, is unknown. Deficits in neurotransmitter systems provide more obvious therapeutic targets and dysfunction of dopaminergic, cholinergic, noradrenergic and serotonergic systems have all been implicated; these may each underlie different features of Parkinson's disease dementia, perhaps explaining some of the heterogeneity of the syndrome. Psychosis has traditionally been considered as a dopaminergic drug-induced phenomenon, but factors intrinsic to the disease process itself also cause hallucinations and delusions. These factors may include Lewy body deposition in the limbic system, cholinergic deficits and impairments of primary visual processing. Therapeutic intervention for cognitive and behavioural symptoms in Parkinson's disease currently focuses on two main groups of drugs: cholinesterase inhibitors and atypical antipsychotics. A recent large, randomised, controlled trial suggests that cholinesterase inhibitors can produce a modest improvement in cognitive function, as well as psychotic symptoms, generally without an adverse effect on motor function. Certain atypical antipsychotics allow hallucinations, delusions and behavioural problems to be brought under control with minimal deleterious effects on motor function and cognition, but their safety in elderly patients has recently been called into question. Deep brain stimulation does not appear to be a useful treatment for cognitive and psychiatric dysfunction in patients with Parkinson's disease. Modafinil improves alertness in Parkinson's disease and warrants further investigation to establish its effects on cognitive performance.

Use of atypical antipsychotics in neurodegenerative diseases

Behavioral and psychotic disturbances are common symptoms in neurodegenerative disorders, and can lead to caregiver stress, nursing home placement and mortality. There is an expanding literature evaluating the effects of atypical antipsychotic (AA) drugs for treating these problems. The results in both primary dementias and Parkinson’s disease suggest that not all AA drugs are equal in terms of efficacy or safety. Furthermore, Parkinsonian and other side effects of the AAs are important to consider when evaluating outcomes. The recent US FDA warning of increased mortality has increased uncertainty in using these drugs. This article reviews the AAs and their use in Parkinson’s disease, dementia with Lewy bodies, Alzheimer’s disease and other associated dementias.

Combating psychosis in Parkinson's disease patients: the use of antipsychotic drugs

Parkinson's disease (PD) patients commonly experience psychotic symptoms, with the most frequent manifestation being visual hallucinations. In PD, psychosis is predominantly drug induced and an important issue for clinicians to address as it increases the risk of nursing home placement as well as mortality. This review summarises the current knowledge regarding the clinical manifestations, pathophysiology and risk factors for drug-induced psychosis in patients with PD and focuses on treatment, especially with regard to the atypical antipsychotics.

Clinical, diagnostic, genetic and management issues in dementia with Lewy bodies

DLB (dementia with Lewy bodies) is a syndrome associated with underlying LBD (Lewy body disease), with manifestations in the cognitive, neuropsychiatric, motor, sleep and autonomic domains. The variable symptomatology and complex array of neuronal involvement and neurotransmitter deficiencies make the diagnosis and management of patients with DLB challenging. The genetic underpinnings of DLB have only recently begun to unfold. In this review, the clinical features, diagnostic criteria, genetics and treatment issues relating to DLB will be discussed, in which a comprehensive approach to the diagnosis and management is emphasized.

Quetiapine Use in a Patient with Chronic Schizophrenia and Severe Parkinsonism

A 52-year-old patient with treatment-resistant paranoid schizophrenia developed severe parkinsonian features after more than 20 years of antipsychotic drug therapy. The role of this therapy was thought to have been a contributing factor to the patient's clinical presentation, although Parkinson's disease could not be ruled out. Originally, parkinsonian symptoms developed acutely and progressed to hand tremor, sialorrhea, upper body rigidity, masked facies, striatal hand, bradykinesia, and a severe, unsteady, shuffling gait. Tremor and rigidity were the only parkinsonian symptoms that responded to anticholinergic therapy. After converting from a first- to a second-generation antipsychotic drug, the patient maintained psychiatric stability, with some improvement in motor functioning-most notably decreased upper body rigidity. Our findings are consistent with the literature on quetiapine therapy in patients with Parkinson's disease in terms of adequately controlling psychosis without worsening motor symptoms. The difference, however, was that in most cases reported, psychotic features were the result of dopamine-enhancing treatments and not schizophrenia.

Double-blind, placebo-controlled, unforced titration parallel trial of quetiapine for dopaminergic-induced hallucinations in Parkinson's disease

We completed a single site, double-blind, placebo-controlled, parallel design study of quetiapine for hallucinations in PD. Thirty-one subjects with PD and prominent visual hallucinations and Mini-Mental State Examination score >21 were randomly assigned in a 2:1 drug to placebo ratio, up to 200 mg daily of quetiapine or matching placebo given in two doses. They were seen at 3 weeks (100 mg/day) and 12 weeks (200 mg/day, with optional dose reduction). Evaluation included the Unified Parkinson's Disease Rating Scale (UPDRS), the Baylor PD Hallucination Questionnaire, and a battery of neuropsychological tests. The demographics between subjects randomized to drug (n = 21) vs. placebo (n = 10) were similar. The final dose of active drug was 200 (n = 11), 150 (n = 2), 100 (n = 3), and 75 (n = 1) mg per day. All placebo subjects were on the equivalent of 200 mg per day. The UPDRS Activities of Daily Living and Motor scores did not significantly change compared to placebo. Compared to placebo, there were no significant changes in our hallucination questionnaire, the Brief Psychiatric Rating Scale (BPRS), or question 12 (hallucination item) of the BPRS. There were no significant changes on any of the neuropsychological measures. Adverse events on drug included sedation (n = 9), but no drug-related adverse events precipitated discontinuation and none were rated as serious. Quetiapine, up to 200 mg daily, was well tolerated and did not worsen UPDRS scores; however, there was no significant improvement in psychosis rating scales compared to placebo. Larger doses of drug and greater sample sizes might be considered in future studies.

Treatment of psychosis in Parkinson's disease: safety considerations

Psychosis only rarely occurs in patients with untreated Parkinson's disease. Much more commonly, psychosis is induced by drug therapy for Parkinson's disease and is the strongest known risk factor for nursing home placement. Delusions are less frequent than hallucinations, but are more concerning as they are often paranoid in nature. Treatment begins with a search for correctable infectious, toxic, and metabolic aetiologies. If symptoms persist, anti-Parkinson's disease medications are slowly reduced. However, withdrawal of these drugs usually worsens parkinsonism and is often not tolerated. Certain atypical antipsychotics can be used to treat psychosis without compromising motor function. The choice of atypical antipsychotic is largely based on ease of use and adverse effect profile as most have comparable efficacy in improving psychosis. Currently, there are five marketed atypical drugs - clozapine, risperidone, olanzapine, quetiapine and ziprasidone. Ziprasidone is the only agent whose adverse effect profile has not been reported in Parkinson's disease. The most common adverse effects of clozapine in Parkinson's disease are sedation, orthostatic hypotension and sialorrhoea. Sedation is generally helpful since these patients are frequently awake at night and tend to have worse behavioural problems then. Clozapine does not induce deterioration of motor function, but it has the potential to cause agranulocytosis, which is idiosyncratic and not dose-related. In risperidone-treated Parkinson's disease patients, reported adverse effects include somnolence, sialorrhoea, dizziness, palpitations, constipation, delirium, fatigue, leg cramps, depression, urinary incontinence and hypotension. Although in some Parkinson's disease studies, risperidone has been well tolerated, others have shown that many patients are unable to tolerate the drug due to deterioration of motor function. While an initial study of olanzapine in Parkinson's disease psychosis showed the drug to be effective without deterioration of motor function, succeeding reports demonstrated a deleterious effect of the drug on motor functioning. The most common adverse effects of quetiapine in Parkinson's disease patients are sedation and orthostatic hypotension. There is a lack of double-blind trials; however, cumulative reports involving >200 Parkinson's disease patients strongly suggest that quetiapine is well tolerated and effective. Unlike clozapine, it does not improve tremor and may induce mild deterioration of motor function. Recently, cholinesterase inhibitors have been reported to alleviate psychosis in Parkinson's disease. Although ondansetron, an antiemetic with antiserotonergic properties, has been reported to relieve psychosis in Parkinson's disease, its prohibitive cost has prevented further study in this population. Electroconvulsive treatment is generally reserved for the patient with psychotic depression who is unable to tolerate any pharmacological therapy.

Atypical antipsychotics in Parkinson-sensitive populations

Drug-induced iatrogenic hallucinations and psychosis occur in about 30% of Parkinson's disease (PD) patients and are the single most important precipitant for nursing home placement, which carries a grave prognosis. In addition, parkinsonism is a frequent accompaniment to the more common dementing syndromes, Alzheimer's disease (AD), vascular dementia, and dementia with Lewy bodies (DLB). The five most recent antipsychotic drugs approved by the Food and Drug Administration in the United States have been marketed as "atypical" antipsychotics (AA) due to their relative freedom from extrapyramidal symptoms when used in schizophrenia patients. The use of these newer antipsychotic drugs in PD and other parkinson-sensitive populations represents the most stringent test to their freedom from motor side effects. To date, clozapine, risperidone, olanzapine, and quetiapine have been studied in parkinson-vulnerable populations. This article reviews the data and highlights the differences that these four drugs have on motor function. It also emphasizes the challenges in evaluating the available data on the motor effects of AA, especially on the non-PD elderly and cognitively impaired population. Suggestions are made for future research to improve the interpretability of these studies.

5-hydroxytryptamine (5-HT, serotonin) and Parkinson's disease - opportunities for novel therapeutics to reduce the problems of levodopa therapy

While Parkinson's disease is undoubtedly a disorder with a primary pathology of dopamine neuronal loss, that loss of dopamine and subsequent dopamine replacement therapy leads to imbalances in many non-dopaminergic transmitter systems, including 5-hydroxytryptamine (5-HT). Recent advances in understanding the role of 5-HT in parkinsonism and the generation of side-effects of dopamine replacement therapy (e.g. wearing-off and levodopa-induced dyskinesia) have identified 5-HT1A, 5-HT1B and 5-HT2C receptors as potential therapeutic targets in Parkinson's disease.

Effects of newer antipsychotics on extrapyramidal function

Following acceptance of clozapine as a superior antipsychotic agent with low risk of adverse extrapyramidal syndromes (EPS), such as dystonia, parkinsonism, akathisia or tardive dyskinesia, several novel antipsychotic drugs have been developed with properties modelled on those of clozapine. Though generally considered 'atypical' in their relatively low risk of inducing EPS, these agents vary considerably in their pharmacology and impact on neurological functioning. Although few comparative data are available, the atypical antipsychotics can be tentatively ranked by EPS risk (excluding akathisia and neuroleptic malignant syndrome) in the following order: clozapine < quetiapine < olanzapine = ziprasidone. At higher doses, risperidone is ranked with a higher EPS risk than olanzapine and ziprasidone, but its risk of EPS is lower with lower doses. In general, this ranking is inversely related to antidopaminergic (D2 receptor) potency. The high antiserotonergic (5-HT2A receptor) potency of risperidone, clozapine, ziprasidone and olanzapine, but not quetiapine, as well as the antimuscarinic activity of olanzapine and clozapine may also limit EPS. For the treatment of psychotic reactions to dopamine agonist therapy in Parkinson's disease, clozapine is both effective and relatively well tolerated; quetiapine may be tolerated, olanzapine is not well tolerated, risperidone is poorly tolerated, and amisulpride and ziprasidone have not been well evaluated. Clozapine, perhaps because of its anticholinergic activity, can reduce parkinsonian tremor. It is useful for ongoing psychosis with tardive dyskinesia, especially for dystonic features. No atypical antipsychotic is clearly effective for motor abnormalities in Huntington's disease or Tourette's syndrome, and the effect of these drugs on other neurological disorders have been well evaluated in only small numbers of patients. In summary, with the exception of clozapine, and perhaps quetiapine, atypical antipsychotics have brought only relative avoidance of EPS, strongly encouraging continued searches for novel antipsychotic agents.

Management of psychosis in Parkinson's disease

Psychosis is quite common in Parkinson's disease (approximately 25% of patients) and therefore constitutes a serious public health problem. All patients suffering from idiopathic Parkinson's disease, and especially elderly and demented patients, are at risk of developing delusions or hallucinations. The most prominent psychotogenic factors are dopaminomimetic agents, which may induce dopamine hypersensitivity in the frontal and limbic dopamine projection regions, and consequently, either directly or indirectly, elicit psychotic signs and symptoms. A Parkinson's disease-related cholinergic deficit in combination with an age-related further loss of cholinergic integrity also plays a prominent role. Psychosis in Parkinson's disease patients appears to be a more important contributor to caregiver distress than motor parkinsonism. Psychosis therefore probably represents the single greatest risk factor for nursing home placement. Typical antipsychotic drugs, because of their selective dopamine receptor antagonistic effects, can reduce psychotic signs but at the cost of an increase in parkinsonism. As a consequence of a non-selective antagonism at both serotonergic and dopaminergic receptors, atypical antipsychotic drugs are associated with fewer extrapyramidal side-effects. On the other hand, hypersensitivity to these agents may induce delirium or a malignant neuroleptic syndrome. Atypical antipsychotic agents such as clozapine, quetiapine and olanzapine should therefore be started at very low doses that are increased gradually. Cholinomimetic therapy may prove to be helpful in the prevention and treatment of psychotic manifestations in Parkinson's disease patients, given the effects observed in patients suffering from dementia with Lewy bodies.

Parkinson's disease: the treatment of drug-induced hallucinations and psychosis

Drug-induced psychosis is one of the most disabling complications of advancing Parkinson's disease. It has also been one of the most difficult to treat. Clozapine was the first medication shown to be safe and effective in this setting, and it remains the standard by which newer atypical antipsychotics are measured. However, due to the small but significant risk of agranulocytosis and the need for frequent blood testing, alternatives have been sought. Risperidone, olanzapine, and quetiapine are new atypical antipsychotics that have each been proposed as an alternative to clozapine, but the literature concerning their use in Parkinson's disease is conflicted and confusing. Although quetiapine appears to be the best current choice, none of these medications have equaled clozapine's ability to safely treat drug-induced psychosis without the risk of worsening parkinsonism.

Psychosis Due to Neurologic Conditions

Psychosis arises with considerable frequency in a number of neurologic conditions. The treatment of such patients is often challenging, as many of the treatments for psychosis pose some risk of worsening the underlying neurologic condition. Although psychosis may emerge in the context of any neurologic condition that sufficiently disrupts the functioning of or connections between limbic, paralimbic, frontal, subcortical areas mediating complex sensory perception, interpretation, and thought or language organization, secondary psychoses are most often encountered in patients with Alzheimer's disease (Parkinson's disease receives dopaminomimetic therapies) and epilepsy. Psychosis, and particularly delusions and visual hallucinations, may arise in Alzheimer's disease. Based on the available literature, the first-line therapy for this problem is risperidone 0.5 to 3 mg per day. If this treatment proves unsuccessful, low-dose haloperidol or olanzapine should be considered next. If these treatments prove unsuccessful, quetiapine should then be considered. Finally, clozapine may be useful for treatment-refractory psychosis due to Alzheimer's disease, but due caution is warranted given its considerable anticholinergic properties and potential for worsening cognition in these patients. Although disease-emergent psychosis (paranoid delusions and visual hallucinations) may develop in patients with Parkinson's disease, psychosis due to dopaminomimetic therapy is much more common. When such symptoms develop, the accepted first step is to taper anti-parkinsonian medications were possible. Anticholinergic medications, amantadine, selegiline, and dopamine receptor agonists should be reduced or discontinued, provided that the patient can tolerate changes in motor symptoms attendant to such reductions. When these reductions are not feasible or fail to improve treatment-emergent psychosis, low-dose quetiapine or clozapine may be useful. The greatest body of evidence supports the effectiveness of these treatments and their relative lack of adverse effects on motor function. When psychosis develops in the context of epilepsy, the generally accepted first step is to maximize anticonvulsant therapy in an effort to reduce the possible contribution of electrophysiologic disturbances in the described areas to psychotic symptoms. When interictal psychosis persists despite such adjustments, initiation with low-dose atypical antipsychotics carries the least risk of lowering seizure threshold and should be considered.

Does risperidone have a place in the treatment of nonschizophrenic patients?

There is a now a substantial body of evidence that suggests the new antipsychotic agent, risperidone, may be safe and effective for treating psychotic, affective or behavioural symptoms associated with various disorders other than schizophrenia, schizophreniform disorder or schizo-affective disorder. These conditions include bipolar disorder, obsessive-compulsive disorder, Tourette's syndrome, dementia, Lewy body disease, mental retardation, Parkinson's disease, idiopathic segmental dystonia and organic catatonia. Although much of the data is anecdotal or in the form of open studies, there is now emerging a small number of well controlled investigations supporting efficacy for mania, dementia, behavioural disturbance in mental retardation and conduct disorder. Conventional antipsychotics have long been used, either in a primary capacity or as an adjunct to treat these disorders; however, they have limited benefit, pose significant risks of extrapyramidal side-effects, and may cause the potentially life-threatening neuroleptic malignant syndrome. In contrast, risperidone at the recommended low doses may be efficacious and pose reduced risk of motor side-effects. This article reviews the evidence that risperidone may be an effective new treatment for disorders other than schizophrenia.