Clozapine-induced stuttering: an estimate of prevalence in the west of Ireland

Abstract

Objectives: Clozapine is the most effective treatment available for treatment-resistant schizophrenia; however, it is also associated with a large array of adverse effects that limits its tolerability. A number of previous case reports have noted an association between clozapine and stuttering, however the rate of this possible adverse effect is yet to be established. Methods: In this paper, we present six cases of patients treated with clozapine who developed stuttering. Results: Clozapine was associated with stuttering in 0.92% of individuals treated with clozapine in the region. Clozapine-induced stuttering was associated with an increase in treatment dose or with dose titration at initiation of clozapine in five individuals, with dose reduction or slower dose titration associated with a cessation of stuttering in these cases. Conclusions: This is the largest case series to date examining clozapine-induced stuttering and indicates that clozapine-induced stuttering is a relatively common adverse effect that can be managed by a slower titration of clozapine dosage or a modest reduction in dose in most cases.

Clozapine-Induced Microseizures, Orofacial Dyskinesia, and Speech Dysfluency in an Adolescent with Treatment Resistant Early Onset Schizophrenia on Concurrent Lithium Therapy

“…While our case also showed seizure-like activity on an EEG that corresponded to the patient's stuttering, there is a discrepancy in the current literature about the etiology of the stuttering. Murphy et al reported that most of the clozapine-induced symptoms resolved without any antiepileptic treatment and two patients with clozapine-induced seizures showed no EEG abnormalities [ 4 ], although a lack of EEG changes does not necessarily preclude the diagnosis of seizures in a clinical setting. The role of antiepileptic pharmacotherapy in cases of clozapine-induced stuttering remains yet unclear, although antiepileptic therapies may have a role in preventing tonic-clonic seizures.…”

“…The potential to cause microseizures may be increased not only with a high dose but also with quicker titration. Murphy et al reported that several patients developed stuttering when their dosage was titrated too rapidly or the target dose was too high and the symptoms resolved with a reduction of the dose by 25–50 mg or with a slower titration schedule [ 4 ]. However, they also reported that one of the patients developed stuttering without any changes in the medication regimen and a dose reduction resulted in no change in the side effect but a recurrence of their psychosis [ 4 ].…”

“…Some of the commonly observed side effects of clozapine include agranulocytosis, decreased seizure threshold, weight gain, cardiomyopathy, orthostatic hypotension, sialorrhea, sedation, constipation, hyperglycemia, and dyslipidemia, while extrapyramidal symptoms such as tardive dyskinesia are relatively less frequently observed [ 2 , 3 ]. In a case series reporting 6 cases of clozapine-induced stuttering, Murphy et al reported an incidence of 0.92% of clozapine-induced stuttering among 654 Irish patients receiving clozapine [ 4 ]. In a 2012 case report on clozapine-induced stuttering, Grover et al reported 16 previous case reports on clozapine associated stuttering [ 5 ].…”

“I Stopped Hearing Voices, Started to Stutter” - A Case of Clozapine-Induced Stuttering

“…A retrospective study in Ireland estimated the prevalence of stuttering as 0.92% (6 of 654) in patients treated with clozapine. [7]…”

Clozapine-induced Weight Loss and Stuttering in a Patient with Schizophrenia

“…Stuttering happens due to rapid titration of dose and higher dose and presence of multiple drugs leading to drug interactions. [ 4 6 ]…”