The main feature of stuttering is the disturbance in terms of both timing and fluency of speech inappropriate with the age. This disturbance is characterized with the repetition and prolongation of sounds and syllables. There are two types of stuttering as acquired and developmental. Acquired stuttering may begin suddenly at any age and may be seen rarely due to the adverse effects of drugs. Stuttering induced by antipsychotics may develop very rarely. Risperidone is a strong antagonist of dopamin 2 (D2) and serotonin 2A (5 HT2A) and shows a high affinity for α1 and α2 noradrenaline receptors. It's used in a wide spectrum including psychotic disorders, mood disorders, and behavioral disorders, even for the treatment of stuttering. Risperidone treats the symptoms of stuttering by the antagonism of D2 receptors with an increase in striatal metabolism. In literature, we haven't observed any other case reports except the two stuttering cases with psychotic disorders due to the short term and high-dose risperidone treatment. In our case, stuttering adverse effect of chronic low-dose risperidone treatment is remarkable that is discussed for the first time. As well as the use of risperidone for the treatment of stuttering, stuttering adverse effect seems to be interesting as a paradox.
Keywords: Risperidone; adverse effects; antipsychotics; stuttering.