A large Danish study reported 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 an age-related decline in tic frequency frequency and severity, but surprisingly the impairment score did not reflect the improvement in tics. severity, but surprisingly the impairment score did not reflect the improvement in tics.
Epidemiology
New and important findings this year involve the previously unappreciated risk of death in TS. \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}.
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}.