Speech and language difficulties have also been implicated. Recent research has focused on linguistic aspects of vocal tics, suggesting that such tics do not occur randomly but are located according to the clausal boundaries or at points of low information within sentences. Other research indicates word finding and speech volume regulation difficulties.
The incidence of TS appears to be unrelated to race or socioeconomic status, although individuals of Jewish or East European heritage may be more commonly affected. People with these origins may have a greater genetic predisposition toward TS, but it seems more likely that referral bias and other cultural factors affect the expression and tolerance of the symptoms. There is no apparent relation of TS to birth weight, birth order, parental age, medical history of individuals or families, or psychiatric history. TS is understood generically to be a complex tic disorder with a lifelong course. A triad of components is necessary to make the diagnosis; the presence of generalized tics and involuntary utterances that may be obscene or suggestive, onset in childhood, and a course that involves a fluctuation of signs throughout the life span but typically is not severely disabling (Heyman and Chowdhury, 2004). The factors that influence the continuity of tic disorders from childhood to adolescence to adulthood are not well understood. Researchers (Waltz, 2001) assume that there is probably an interaction between maturation of the central nervous system and emotional distress along the maturational course. Environmental factors (e.g., toxins and infections) and genetic factors have been cited as possible etiologic factors in this group of disorders. Also, "and physical exhaustion will increase the likelihood of tics occurring" (Hendren 2002, p. 22).
Neurobiological models TS stress the role of 5-HT in pathophysiological mechanisms. In some studies, pharmacological challenge with oral m-chlorophenylpiperazine (m-CPP), a partial serotonergic agonist, produced increased severity of TS symptoms in a subgroup of obsessive-compulsive disorders patients studied (Heyman and Chowdhury, 2004). The factors that determine the degree of disability probably include the presence of additional developmental, mental and behavioral disorders. The level of resilience may depend upon support and understanding from parents, peers, and educators and the presence of special abilities or personal attributes. When TS was first identified, the prognosis was thought to be poor, and the majority of cases were assigned to long-term hospitalization. Today, the outlook for TS generally is considered to be good; most individuals experience their worst tic symptoms between nine and 15 years of age (Shimberg, 1995).
TS is considered a genetic disease. In spite of the fact that its basic cause is still unknown, researchers found that TS is caused by an abnormal gene that alters functions of neurotransmitters such as dopamine, norepinephrine and serotonin. Current research presents considerable evidence that TS stems from the abnormal metabolism of at least one brain chemical, the