Stuttering: Neuropsychiatric features measured by content analysis of speech and the effect of risperidone on stuttering severity

Abstract

Positron-emission tomographic (PET) studies and genetic research of stuttering have recently revealed underlying cerebral neurobiologic contributing factors in this disorder. We aimed to assess whether cognitive impairment and other neuropsychiatric dimensions could be detected through computerized content analysis of short samples of speech from stutterers, and whether administration of risperidone in a double-blind placebo-controlled study could decrease the severity of stuttering, as well as any of the neuropsychiatric features of these stutterers. A group of 21 stutterers with the developmental form of stuttering, an onset before age of 6 years, aged 20 to 74 years, and who were otherwise free of major medical or psychiatric problems, initially gave a 5-minute tape-recorded speech sample in response to purposely ambiguous instructions to talk about any interesting or dramatic life experiences. Then, half of these subjects (n = 10) were randomly selected to receive 6 weeks of risperidone treatment up to 2.0 mg/d and the other half (n = 11) were administered a placebo. Both groups of subjects gave a second verbal sample after 6 weeks of treatment. Significantly elevated cognitive impairment and social alienation-personal disorganization scores, derived from the computerized content of the initial 5-minute speech samples, were found. After 6 weeks, the risperidone group improved significantly on a measure of severity of stuttering but did not improve on the percentage of time spent stuttering. The placebo group did not improve on either measure of stuttering. The psychopathological processes of subjects who received risperidone treatment, including those with elevated cognitive impairment and social alienation-personal disorganization, did not change significantly. However, stutterers who had lower scores on verbal content analysis-derived shame anxiety, guilt anxiety, or hostility inward measures improved significantly more with risperidone than stutterers with higher scores on these measures. The findings of elevated cognitive impairment and social alienation-personal disorganization scores of adult stutterers with the early developmental form of stuttering are consistent with the neurobiologic abnormalities found in PET scan and genetic research involving stutterers. Risperidone (≤2.0 mg/d) can reduce the severity of stuttering while not significantly affecting the magnitude of neuropsychiatric dimensions such as cognitive impairment or social alienation-personal disorganization. The less the inward shame, guilt, or hostility of the stutterers, the better the beneficial effect of risperidone on the severity of stuttering.