Phenomenology and natural history
\citet{28289551} describe 16 people with Tourette syndrome who had experienced a clinical remission or marked improvement of more than 1 year's duration, followed by symptomatic worsening as adults, leading them again to seek treatment. On average the "latent period" (the absence or substantial reduction in tics) had lasted 16 years. Seven of them had worse tics when returning for care than they recalled as children. New substance use was reported as a trigger for exacerbation in 5 patients. This report strengthens evidence that even long-lasting symptomatic improvement in tic disorders may not always be permanent, and that in fact the typical course of TS "is one of occasional recurrences of mild tics throughout adult life" \citep*{Bruun1997}; see also \citep{e1988,Stárková1990,16389220,27158458a}.
Regarding natural course and history, the fate of non-tic symptoms in TS has remained less well explored. A large Danish study reported follow-up data 6 years after enrolling 314 children and teenagers with Tourette syndrome, assessing tics and comorbidities (mainly OCD and ADHD; N=226 at follow-up) \citep{28335874}. Most patients' tics improved over time, but almost a quarter of those over age 16 still had severe tics, and only a sixth had no tics. The severity of OCD and ADHD declined significantly during adolescence, suggesting a shift towards so-called "pure" TS with age. Furthermore, the authors expected tic-related impairment to improve with an age-related decline in tic frequency and severity, but surprisingly the impairment score did not reflect the improvement in tics.
A report on 606 patients with a movement disorder starting in childhood produced an estimate for tic onset of 7.4 ± 3.8 years with a mean delay to diagnosis of 9.9 ± 11 years \citep{Baumer:2016}.
Epidemiology
New and important findings this year involve the previously unappreciated risk of death in tic disorders. \citet{28339122} demonstrated that mortality rates are elevated in TS and other tic disorders, with or without comorbidities. In a very large epidemiological study, tic disorders in adults were associated with a four-fold higher risk of suicide, with the risk not explained by other psychiatric illness such as major depression \citep{27773353}. These researchers analyzed 7736 TD/CTD cases in the Swedish National Patient Register over a 44-year period (1969-2013) and compared them with general population control subjects. TD/CTD patients, compared with control subjects, had an increased risk of both dying by suicide and attempting suicide. Importantly, even after adjusting for psychiatric comorbidities, the risk was reduced but remained substantial. Persistence of tics beyond young adulthood and a previous suicide attempt were the strongest predictors of death by suicide in TD/CTD patients. The authors conclude, and we strongly agree, that suicidal behavior should be monitored in these patients, particularly in those with persistent tics, history of suicide attempts, and psychiatric comorbidities. The same group found a 7- to 10-fold higher risk of completed suicide in people with OCD, even after controlling for comorbid diagnoses \citep{27431293}.
\citet{28071825} review screening instruments and rating scales for tic disorders; see also \citep{28436544,28436554}.