Having a chronic tic disorder like Tourette syndrome (TS) may double the risk of developing cardiometabolic disorders like diabetes or heart disease, according to findings published online on January 14, 2019, in JAMA Neurology.1
The study is the first to evaluate cardiometabolic risk in chronic tic disorders on a nationwide scale. It included data on over 14 million people living in Sweden across a 40 year time span.
Results showed that about 52% of people with a chronic tic disorder would develop at least one cardiometabolic disorder by about age 40, compared with about 30% in the general population. The increased risk appeared to begin in childhood, and may be even higher for people who also have ADHD.
“The results highlight the importance of carefully monitoring cardiometabolic health in patients with TS or other chronic tic disorders across the lifespan, particularly in those with comorbid attention-deficit/hyperactivity disorder,” wrote senior author Lorena Fernández de la Cruz, PhD, of the Karolinska Institutet, (Stockholm, Sweden), and colleagues.
TS and other chronic tic disorders affect about 1% of the population and are more common in males.2 While tic disorders have been linked to increased risk of early death,3 the underlying causes have yet to be understood. Individuals with tic disorders often have chronic stressors in their life, lower education levels and unhealthy lifestyles, all of which may increase cardiometabolic risk.
To study the issue, researchers used Swedish nationwide databases to analyze diagnoses of obesity, dyslipidemia, hypertension, type 2 diabetes, and cardiovascular disease among people with chronic tic disorders, compared to the general population. The study included 14,045,026 individuals living in Sweden between January 1973 and December 2013, of which 7804 had TS or chronic tic disorders. Of these, 76.4% were male.
To weed out factors in the home that could increase cardiometabolic risk, researchers also included comparisons for 5141 families that had at least one sibling with a tic disorder and one sibling without.
They also looked at the influence of antipsychotic medication and comorbid psychiatric disorders (ADHD, obsessive compulsive disorder, bipolar disorder, and anxiety disorders). Results were adjusted for age and sex. Mean followup was 22.2 years
Results showed significantly increased risk of cardiometabolic disorders among people with chronic tic disorders, compared to the general population (HR adjusted by sex and birth year [aHR], 1.99; 95%CI, 1.90-2.09), and compared to siblings without tic disorders (aHR for any disorder, 1.37; 95%CI, 1.24-1.51).
Individuals with tic disorders had about 2.8 times increased risk for obesity, (aHR, 2.76; 95%CI, 2.47-3.09), over 1.5 times increased risk for type 2 diabetes (aHR, 1.67; 95%CI, 1.42-1.96), and about 1.8 times increased risk for circulatory system diseases (aHR, 1.76; 95%CI, 1.67-1.86), compared to the general population.
Cardiometabolic risk in those with tic disorders was significantly increased as early as age 8.
Excluding ADHD from the analysis weakened the association but did not erase it (aHR, 1.52; 95%CI, 1.42-1.62), suggesting that ADHD may substantially add to cardiometabolic risk.
Strangely, use of antipsychotics was not linked to increased cardiometabolic risk at one year (aHR, 0.83; 95% CI, 0.56-1.24), or over the long-term (greater than one year: aHR, 0.27; 95% CI, 0.17-0.43).
Several past studies have linked antipsychotics to increased cardiometabolic risk. The authors noted that individuals on antipsychotics may have closer followup and monitoring of their general health, which may affect cardiometabolic risk.
“Our results should not be taken as evidence that antipsychotics are free from cardiometabolic adverse effects, and they should continue to be used with caution in this patient group,” they wrote.
The authors mentioned several limitations. Until 2001, the Swedish registers did not include patients diagnosed with tic disorders in primary care, so results may not apply to individuals with mild tics. The registers also did not have data on factors such as sedentariness, unhealthy diet and smoking, which could affect cardiometabolic risk.
Take Home Points
• Large, nationwide Swedish cohort study with a 40 year time span found that people with chronic tic disorders had double the risk for cardiometabolic disorders compared to the general population
• Risk for obesity, type 2 diagetes, and circulatory system diseases was significantly increased with tic disorders compared to the general population
• Comorbid ADHD may contribute to increased cardiometabolic risk in tic disorders
1. Brander G, Isomura K, Chang Z. et al. Association of Tourette Syndrome and Chronic Tic Disorder With Metabolic and Cardiovascular Disorders. JAMA Neurol. 2019 Jan 14. doi: 10.1001/jamaneurol.2018.4279.
2. Robertson MM. A personal 35 year perspective on Gilles de la Tourette syndrome: prevalence, phenomenology, comorbidities, and coexistent psychopathologies. Lancet Psychiatry. 2015;2:68-87.
3. Meier SM, Dalsgaard S, Mortensen PB, et al. Mortality risk in a nationwide cohort of individuals with tic disorders and with Tourette syndrome. Mov Disord. 2017;32:605-609.