Syntactic and semantic correlates of verbal tics in Gilles de la Tourette's syndrome: A quantitative case study

Abstract

A two-hour sample of the speech of a patient suffering from Gilles de la Tourette's syndrome was analyzed. Coprolalic verbal tics are a major symptom of this disorder. In contrast to findings with other speech dysfluencies, verbal tics in Gilles de la Tourette's syndrome tend to occur at points of low information or uncertainty in sentences. They were found to be especially probable before conjunctions and pronouns. Sentences containing verbal tics exhibited more primary process and less secondary process content than sentences not containing tics. Tic sentence words were connotatively less potent, less active, less evaluatively negative, and more aggressive than words in nontic sentences. A neurolinguistic model of the syndrome is proposed: Necessity for grammatical coordination elicits the tic because of overactivity of subcortical centers that mediate this operation. Semantic determinants of the tic hypothetically operate by influencing cortical arousal which in turn triggers the subcortical centers.