The natural history of TS follows a relatively predictable course, characterized by onset of motor tics between ages 3 and 8 years, followed by vocal tics.[2]Leckman JF, Zhang H, Vitale A, et al. Course of tic severity in Tourette syndrome: the first two decades. Pediatrics. 1998;102:14-19.
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The tics typically wax and wane and vary with different day-to-day environmental factors. Tics typically peak in late childhood before puberty, and usually attenuate or remit during and after adolescence.[3]Bloch MH, Peterson BS, Scahill L, et al. Adulthood outcome of tic and obsessive-compulsive symptom severity in children with Tourette syndrome. Arch Pediatr Adolesc Med. 2006;160:65-69.
http://archpedi.ama-assn.org/cgi/content/full/160/1/65
http://www.ncbi.nlm.nih.gov/pubmed/16389213?tool=bestpractice.com
A prospective longitudinal study of 46 children followed until 14 years of age showed that the most severe period of tics occurs at 10 years of age, and that the severity of tics tends to decrease during adolescence.[3]Bloch MH, Peterson BS, Scahill L, et al. Adulthood outcome of tic and obsessive-compulsive symptom severity in children with Tourette syndrome. Arch Pediatr Adolesc Med. 2006;160:65-69.
http://archpedi.ama-assn.org/cgi/content/full/160/1/65
http://www.ncbi.nlm.nih.gov/pubmed/16389213?tool=bestpractice.com
In these patients, the highest severity of OCD symptoms occurred 2 years after the most severe period of tics. ADHD was not associated with the presence or severity of tics or OCD in TS. Of further prognostic interest is that late childhood tic severity is modestly predictive of severity later in life.[127]Goetz CG, Tanner CM, Stebbins GT, et al. Adult tics in Gilles de la Tourette's syndrome: description and risk factors. Neurology. 1992;42:784-788.
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Other predictors of tic severity in adulthood have been described, including female sex, smaller caudate volumes, and poorer fine-motor control.[128]Lichter DG, Finnegan SG. Influence of gender on Tourette syndrome beyond adolescence. Eur Psychiatry. 2015;30:334-340.
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[129]Hassan N, Cavanna AE. The prognosis of Tourette syndrome: implications for clinical practice. Funct Neurol. 2012;27:23-27.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3812751
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In another study, whereas 81% of patients less than 18 years of age required medication, only 41% of patients over 18 years of age were still taking medication.[130]Erenberg G, Cruse RP, Rothner AD. The natural history of Tourette syndrome: a follow-up study. Ann Neurol. 1987;22:383-385.
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Patients with ADHD may have higher rates of other behavioral disorders, which may be associated with more functional impairment.[2]Leckman JF, Zhang H, Vitale A, et al. Course of tic severity in Tourette syndrome: the first two decades. Pediatrics. 1998;102:14-19.
http://www.ncbi.nlm.nih.gov/pubmed/9651407?tool=bestpractice.com
In a more recent study comparing older adolescents with TS with healthy adolescents in the community, TS patients were found to have higher rates of overall psychiatric comorbidity, OCD, and ADHD.[131]Gorman DA, Thompson N, Plessen KJ, et al. Psychosocial outcome and psychiatric comorbidity in older adolescents with Tourette syndrome: controlled study. Br J Psychiatry. 2010;197:36-44.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2894981
http://www.ncbi.nlm.nih.gov/pubmed/20592431?tool=bestpractice.com
However, independent of ADHD, the TS adolescents had higher rates of major depression. The presence of depression has been related to suicidal ideation[132]Johnco C, McGuire JF, McBride NM, et al. Suicidal ideation in youth with tic disorders. J Affect Disord. 2016;200:204-211.
http://www.ncbi.nlm.nih.gov/pubmed/27136419?tool=bestpractice.com
[133]Storch EA, Hanks CE, Mink JW, et al. Suicidal thoughts and behaviors in children and adolescents with chronic tic disorders. Depress Anxiety. 2015;32:744-753.
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and poorer quality of life in patients with TS.[134]Evans J, Seri S, Cavanna AE. The effects of Gilles de la Tourette syndrome and other chronic tic disorders on quality of life across the lifespan: a systematic review. Eur Child Adolesc Psychiatry. 2016 Feb 15 [Epub ahead of print].
http://link.springer.com/article/10.1007%2Fs00787-016-0823-8
http://www.ncbi.nlm.nih.gov/pubmed/26880181?tool=bestpractice.com
Whether this is a neurobiological risk factor, a result of living with a chronic disease, or both, requires further study.[131]Gorman DA, Thompson N, Plessen KJ, et al. Psychosocial outcome and psychiatric comorbidity in older adolescents with Tourette syndrome: controlled study. Br J Psychiatry. 2010;197:36-44.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2894981
http://www.ncbi.nlm.nih.gov/pubmed/20592431?tool=bestpractice.com
However, the overall picture is favorable and, by early adulthood, only approximately 20% of patients will still have moderately debilitating tics; most will have mild tics and some will have remission of their symptoms.[135]Bruun RD. Gilles de la Tourette's syndrome. An overview of clinical experience. J Am Acad Child Psychiatry. 1984;23:126-133.
http://www.ncbi.nlm.nih.gov/pubmed/6585414?tool=bestpractice.com