Pérez-Vigil A, et al. - In this Swedish cohort study that involved more than 2 million people, researchers examined the connection of Tourette syndrome and chronic tic disorders with objectively measured educational outcomes, adjusting for measured covariates and unmeasured factors shared between siblings and taking common psychiatric comorbidities into account. Results of this study suggested that help-seeking individuals with Tourette syndrome or chronic tic disorders diagnosed in specialist care can experience substantial academic underachievement across the lifespan.

Methods

• A population-based birth cohort comprising of all people born in Sweden from 1976 to 1998 was followed up until December 2013.
• In this analysis, researchers excluded people with organic brain disorders, mental retardation, and 2 foreign-born parents.
• Families with at least 2 singleton full siblings and families with siblings discordant for Tourette syndrome or chronic tic disorders were identified.
• Main exposures analyzed were previously validated International Classification of Diseases diagnoses of Tourette syndrome or chronic tic disorders in the Swedish National Patient Register.
• Main outcomes measured were eligibility to access upper secondary school after compulsory education, finishing upper secondary school, starting a university degree, and finishing a university degree.

Results

• As per data, out of 2,115,554 people in the cohort, 3590 had registered a diagnosis of Tourette syndrome or a chronic tic disorder in specialist care (of whom 2822 [78.6%] were male; median [interquartile] age at first diagnosis, 14.0 [11-18] years).
• Out of 726,198 families with at least 2 singleton full siblings, 2697 included siblings discordant for these disorders.
• People with Tourette syndrome or chronic tic disorders were significantly less likely to pass all core and additional courses at the end of compulsory school (odds ratios ranging from 0.23 [95% CI, 0.20-0.26] for the handcraft textile/wood course to 0.36 [95% CI, 0.31-0.41] for the English language course) and to access a vocational program (adjusted OR [aOR], 0.31; 95% CI, 0.28-0.34) or academic program (aOR, 0.43; 95% CI, 0.39-0.47) in upper secondary education vs unexposed individuals.
• In addition, people with these disorders were less likely to finish upper secondary education (aOR, 0.35; 95% CI, 0.32-0.37), start a university degree (aOR, 0.41; 95% CI, 0.37-0.46), and finish a university degree (aOR, 0.39; 95% CI, 0.32-0.48).
• In the fully adjusted sibling comparison models, the outcomes were only marginally attenuated.
• Exclusion of subjects with neuropsychiatric comorbidities, especially attention-deficit/hyperactivity disorder and pervasive developmental disorders, resulted in attenuated estimates.
However, patients with Tourette syndrome or chronic tic disorders were still significantly impaired across all outcomes.