Thirty-four of 170 surveyed individuals with Tourette's syndrome (TS) were treated with CNS stimulants before age 18. In 24% of treated individuals, persistent exacerbation of tics was closely associated with treatment. In 3%, tic response was transient, and in 24%, tics were not obviously associated with treatment. Six pairs of monozygotic twins were discordant for stimulant treatment, and all untreated co-twins also developed TS. The number of individuals in whom stimulants permanently exacerbate tics may be small, but the risk appears to be real. Genetic vulnerability and duration and timing of treatment may mediate response.
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"Tourette syndrome (TS) is a chronic neuropsychiatric disorder which begins in childhood and is characterized by the presence of multiple motor and phonic tics (Singer and Walkup 1991). Support for a genetic component to TS comes from many lines of evidence, including twin studies (Price et al. 1986; Hyde et al. 1992) and family Received November 7, 1995; accepted for publication June 3, 1996. Address for correspondence and reprints: Dr. John T. Walkup, "
[Show abstract][Hide abstract] ABSTRACT: To investigate the transmission of Tourette syndrome (TS) and associated disorders within families, complex segregation analysis was performed on family study data obtained from 53 independently ascertained children and adolescents with TS and their 154 first-degree relatives. The results suggest that the susceptibility for TS is conveyed by a major locus in combination with a multifactorial background. Other models of inheritance were definitively rejected, including strictly polygenic models, all single major locus models, and mixed models with dominant and recessive major loci. The frequency of the TS susceptibility allele was estimated to be .01. The major locus accounts for over half of the phenotypic variance for TS, whereas the multifactorial background accounts for approximately 40% of phenotypic variance. Penetrance estimates suggest that all individuals homozygous for the susceptibility allele at the major locus are affected, whereas only 2.2% of males and 0.3% of females heterozygous at the major locus are affected. Of individuals affected with TS, approximately 62% are heterozygous and approximately 38% are homozygous at the major locus. While none of the families had two parents affected with TS, 19% of families had two parents affected with the broader, phenotype, which includes TS, chronic tic disorder, or obsessive-compulsive disorder.
Full-text · Article · Oct 1996 · The American Journal of Human Genetics
"This concern was later demonstrated to be unwarranted (e.g. Price et al., 1986). Today it is generally believed that stimulant medications may exacerbate tics in a particular subset of the TS population when the drug is first introduced, but that these initial symptom aggravations often later subside (Gilbert, 2001). "