Stuttering, a disturbance in the normal fluency and time patterning of speech is usually developmental. In some cases, it is acquired, and causes include
stroke,
brain tumor, and
trauma. Implicated in the causation of
stuttering are overactive presynaptic
dopamine systems in the region of the brain that modulate verbalization. It is a rare side effect of
antipsychotic medications and has been reported with
phenothiazines,
clozapine, and
risperidone. This is a report of a patient who developed
stuttering when treated first with
chlorpromazine and later with
risperidone. Patient had a diagnosis of
schizoaffective disorder and had been treated with
antipsychotic medications including
haloperidol,
olanzapine, and
paliperidone. He developed
stuttering for the first time upon receiving
intramuscular injections of
chlorpromazine for treatment of agitation. The stutter improved and eventually resolved. He subsequently presented with a severe stutter when he was treated with
risperidone. The stutter improved after
risperidone was discontinued. It is speculated that
drug-induced
stuttering may be a manifestation of
akathisia leading to noradrenergic and serotonergic mechanisms being implicated. It could be that either the
cholinergic, dopaminergic or serotonergic systems are involved or that there is an imbalance of these systems that may be relevant.