It is 10.30pm. I lie in bed. My eyes close but I cannot sleep. I hear my twelve-year-old son from his room. He lies in bed and snorts. The air leaves his nostrils in loud dramatic puffs. I count the repetitive sounds. He snorts about every three seconds. This behaviour continues until he finally sleeps. I doze off. Snorting is just one of his tics.
My son has Tourette’s syndrome. He displays unusual repetitive behaviours. These include both vocal tics and motor, or physical, tics. Tourette’s patients exhibit at least one vocal and one motor tic at any given time for at least one year. Tics wax and wane in their intensity. Tics appear and disappear without warning. One tic may replace another, but a child is rarely tic-free.
The Bigger Picture
My son also displays Attention Deficit Hyperactivity Disorder (ADHD). He blurts out information and fidgets incessantly. He also manifests obsessive-compulsive behaviours. He scrubs his teeth several times before sleep.
According to a 2015 case study published by The Journal of Child and Adolescent Psychopharmacology, my son is not alone in his triple diagnosis. Dr. Rice, the study’s lead researcher, refers to the co-occurrence of Tourette’s syndrome, Obsessive Compulsive Disorder (OCD), and ADHD as the “triad.”
Dr. Rice states that while the disorders often co-occur, symptoms have a unique developmental course in each child. My son displayed the “triad” just shy of his seventh birthday.
The Basal Ganglia
Dr. Rice states that the brain region called the Basal Ganglia connects the three disorders. The Basal Ganglia sits at the bottom of the forebrain. Researchers believe the basal ganglia co-ordinates voluntary motor movements. Voluntary movements include the learned repetitive behaviours witnessed in Tourette’s patients and OCD. The Basal Ganglia connects to the Pre-Frontal Cortex, the centre of higher reasoning. Dr. Rice explains that the two regions work together to improve memory and decision-making functions. Impulsive behaviours may result from deficits in connectivity between the regions.
Is it Genetic?
Research suggests all three disorders share genetic links, yet to date, no research has identified the culprit. Dr. Rice describes the inherited deficit as “a punitive phenotype,” or an inherited lack of inhibitory control.
The developmental course of the disorder means the most disruptive behaviours associated with ADHD often appear in early childhood. Tics usually manifest in the early school years, while obsessions and compulsions often peak in adolescence.
Medication and Tics
Many children with ADHD take medication to aid concentration and curb hyperactivity. Previous research failed to prove whether these medications aggravate tic behaviours. But current research by the American Academy of Child and Adolescent Psychiatry reports that medications used to treat symptoms of ADHD do not exacerbate tics in children.
The findings of the study are particularly pertinent because most prior research suggests that psycho-stimulant medications trigger tics. As a result, the Food and Drug Administration Agency of the United States (FDA) issues warnings on all psycho-stimulant medications listing tics as an adverse effect. The warnings deter doctors from prescribing psycho-stimulants to any child with a family history of tics. Psycho-stimulants remain the best-known solution for ADHD symptoms.
What are Psycho-stimulant Medications?
Psycho-stimulants, or amphetamines, activate the central nervous system to increase dopamine in the brain. Dopamine is an important neurotransmitter. Neurotransmitters help connectivity between brain regions. For ADHD patients, increasing connectivity between brain regions improves concentration and reduces the behavioural issues associated with impulsivity.
Researchers performed a meta-analysis to examine whether medications increased tics. A meta-analysis looks at previous studies and compares results. Researchers compared twenty-two previous studies from a total of 2385 children with ADHD. The twenty-two studies together included data sets collected between 1974 and 2011.
All studies reported some increased tic behaviour after either trials with a psycho-stimulant medication, or a non-active placebo medication. All trials lasted at least seven days. The Yale Global Tic Severity Scale considers a seven-day trial the minimum sufficient for successful clinical testing.
Results of the Study
Tic behaviours increased the most after placebo treatments. Psycho-stimulant medications designed for ADHD did not increase tics. Researchers examined all FDA approved ADHD medications.
What Causes the Tics?
This new study shows ADHD medications do not exacerbate tics. Aligning with Dr. Rice’s claims, the new study suggests that tics probably result from an underlying predisposition to a tic disorder. Twenty percent of children diagnosed with ADHD posses an underlying tic disorder. Psycho-stimulant treatments generally commence before tics appear. Increases in subsequent tic behaviour may be coincidental.
Should We Medicate?
Although the new study indicates that ADHD medications do not intensify tics in children, other known side effects exist. Common side effects include appetite loss and insomnia. It is important to remember, however, that poor social skills and low academic performance often affect young ADHD patients more than any known side effect.
For my son, treating his ADHD with medication improves his social and educative success.
As for his tics, we hope they will wane naturally with age.
Berman, S. M., Kuczenski, R., McCracken, J. T., & London, E. D. (2009). Potential adverse effects of amphetamine treatment on brain and behavior: A review. Molecular Psychiatry, 14(2), 123–142. http://doi.org/10.1038/mp.2008.90
Cohen, S. C., Mulqueen, J. M., Ferracioli-Oda, E., Stuckelman, Z. D., Coughlin, C. G., Leckman, J. F., & Bloch, M. H. (2015). Meta-analysis: Risk of tics associated with psychostimulant use in randomized, placebo-controlled trials. Journal of the American Academy of Child & Adolescent Psychiatry, 54(9), 728-736. doi:10.1016/j.jaac.2015.06.011
Himle, M. B., Chang, S., Woods, D. W., Bunaciu, L., Pearlman, A., Buzzella, B., & Piacentini, J. C. (2007). Evaluating the contributions of ADHD, OCD, and tic symptoms in predicting functional competence in children with tic disorders. Journal of Developmental and Physical Disabilities, 19(5), 503-512. doi:10.1007/s10882-007-9066-4
Hirschtritt, M.E., Lee, P.C., Pauls, D.L., Dion, Y., Grados, M.A., Illmann, C., King, R.A., Sandor, P., McMahon, W.M., Lyon, G.J., Cath, D.C., Kurlan, R., Robertson, M.M., Osiecki, L., Scharf, J.M. &, Mathews, C.A. (2015). Lifetime prevalence, age of risk, and genetic relationships of comorbid psychiatric disorders in Tourette syndrome. JAMA Psychiatry.72(4), 325–333. doi:10.1001/jamapsychiatry.2014.2650
Khajehpiri, Z., Mahmoudi-Gharaei, J., Faghihi, T., Karimzadeh, I., Khalili, H., & Mohammadi, M. (2014). Adverse reactions of methylphenidate in children with attention deficit-hyperactivity disorder: Report from a referral center. Journal of Research in Pharmacy Practice, 3(4), 130–136. http://doi.org/10.4103/2279-042X.145389
Lebowitz, E., Motlagh, M., Katsovich, L., King, R., Lombroso, P., Grantz, H., Lin, H., Belntley, J., Gilbert, D., Singer, H., Coffey, B., Kurlan, R., & Leckman, J. (2012). Tourette syndrome in youth with and without obsessive-compulsive disorder and attention deficit hyperactivity disorder. European Child & Adolescent Psychiatry, 21(8), 451-457. doi:10.1007/s00787-012-0278-5
Rice, T., & Coffey, B. (2015). Pharmacotherapeutic challenges in treatment of a child with “the triad” of obsessive compulsive disorder, attention- deficit/hyperactivity disorder and tourette’s disorder. Journal of Child and Adolescent Psychopharmacology, 25(2), 176-179. doi: 10.1089/cap.2015.2522
Published in Communicating Science. A text for the University of Toronto, 2019
Chronic smoking blackens your lungs, blocks your arteries, and causes bad breath. But how does excessive pregnant puffing affect the unborn child? Could the drag of a smoke while pregnant cause Tourette’s syndrome?
Between 1996 and 2002, the Danish National Birth Cohort (DNBC) interviewed, observed, and collected data about the lifestyle, health, and habits of nearly 100,000 pregnant Danish women. By October 2013, after re-interviewing, observing, and collecting new data from the Danish mother’s, the DNBC composed a complete data set of 73,076 women and their now teenage children.
In 2017, Dr. Browne and her team from the Icahn School of Medicine in New York studied the comprehensive Danish data to determine whether chronic smoking during pregnancy might cause Tourette’s syndrome, a neurological disorder responsible for chronic tic behaviours.
Before we delve into Dr. Browne’s findings, let’s first examine the symptoms of Tourette’s syndrome and how it affects the brain.
Tourette’s Syndrome and Tics
Doctors believe that Tourette’s syndrome arises from alterations in the development of brain circuits during pregnancy. Specifically, subtle changes may occur in the Thalamus, Basal Ganglia, and the Pre-Frontal Cortex. Tics, or sudden repetitive movements observed in patients with Tourette’s syndrome likely result from deficits in connectivity between these regions. Patients with Tourette’s syndrome display both physical and vocal tics over the course of at least one year.
Dr. Herrero and his associates from University of Murcia, Spain, explain that the Thalamus and Basal Ganglia sit at the bottom of the forebrain and help coordinate voluntary motor movements and behaviours. The two areas connect to the Pre-Frontal Cortex, the centre of higher reasoning. Dr. Herrero claims that together, the three regions aid working memory, decision-making functions, and voluntary movement.
According to Dr. Herrero, the Thalamus, Basal Ganglia, and the Pre-Frontal Cortex work together to coordinate voluntary movements
Tic behaviours also likely occur because of altered dopamine levels.
Dr. Herrero explains that dopamine, a neurotransmitter or a chemical messenger in the brain, allows information to pass from one neuron to another. Altered dopamine levels likely reduce connectivity between brain regions. Altered dopamine may explain the reduced voluntary control, or tics behaviours, observed in Tourette’s patients.
Dopamine, a neurotransmitter, sends a chemical message from one neuron to another.
The DNBC interviewed pregnant women at their 17th and 32nd week of pregnancy, and again six months after the birth of their child. During interviews, each mother disclosed whether or not she smoked. Researchers categorised the mothers’ daily cigarette consumption as either light or heavy. Light smokers puffed fewer than ten daily cigarettes, while heavy smokers dragged on more than ten.
The DNBC also collected data on the child’s sex, birth weight, mother’s age, mother’s pregnant body mass index (BMI), parental income, and parental alcohol, hashish and caffeine consumption. 73,076 of the participants possessed a complete set of data. Dr. Browne and her team or possibly influential variables from the complete data set to ensure no other factor influenced a diagnosis of Tourette’s syndrome.
The team linked the information from the DNBC with information from the Danish National Psychiatric Central Register (DNPCR). They discovered 906 reported cases of chronic tic behaviours or diagnosed Tourette’s syndrome among the teenage cohort.
Dr. Browne and her team confirmed prenatal smoking increases the risk of the child developing Tourette’s syndrome, stating, “Heavy smoking was associated with a 66% increased risk.”
Data from the DNPCR also showed increased links between chronic prenatal smoking and Attention Deficit Hyperactivity Disorder (ADHD). Children with ADHD display attention difficulties and hyperactive behaviour. Dr. Browne and her team claim heavy prenatal smoking doubled the risk of acquiring both ADHD and Tourette’s syndrome in the sample of teens.
Eight percent of mothers in the study confessed to heavy daily smoking during their pregnancy.
Smoking and the brain
Research suggests that prenatal exposure to nicotine affects foetal brain maturation. Affected children’s brain circuitry may wire unconventionally as a result. Their altered dopamine levels may cause neurons to fire with no target in sight.
Brain structures may also look different. Depleted behavioural and voluntary motor control observed in Tourette’s syndrome and ADHD might result from these brain re-structures.
Browne, H. A., Modabbernia, A., Buxbaum, J. D., Hansen, S. N., Schendel, D. E., Parner, E. T., Grice, D. E. (2016). Prenatal maternal smoking and increased risk for Tourette syndrome and chronic tic disorders. Journal of the American Academy of Child & Adolescent Psychiatry, doi:10.1016/j.jaac.2016.06.010 Herrero, M., Barcia, C., & Navarro, J. (2002).
Functional anatomy of thalamus and basal ganglia. Child’s Nervous System, 18(8), 386-404. doi:10.1007/s00381-002-0604-1 4 1
Published in Communicating Science. A text for the University of Toronto, 2019