What You Need to Know about ADHD Tic and Stimming Behaviors

When my son was in high school, he had the opportunity to participate in a research study on the neurobiology of ADHD in children and adolescents. My son has always been open about his ADHD, so I asked him if he wanted to participate in the study (I am not ashamed to admit that the neuroscientist in me just wanted an image of my son’s ADHD brain). My son agreed, so I contacted the study organizer to schedule the interview to see whether my son would qualify for the study.

Among the list of questions from the interviewer was whether my son had any tics—the repetitive facial movements and vocalizations common in ADHD. My son did have ADHD-associated tics, including rubbing his lips raw until they would bleed, repetitively squeezing his eyes closed then opening them, and opening his mouth wide. The interviewer asked me if my son had any repetitive vocalizations and I mentioned that he frequently cleared his throat and often hummed.

A few days later I received a call from the lead investigator wanting to know more about my son’s facial movements and vocalizations. After some discussion he disqualified my son from the study explaining that he may have a mild form of Tourette syndrome.

Tics and Tourette Syndrome in ADHD

Tics are common in childhood, with boys three times more likely than girls to have tics. Children with ADHD exhibit tic behaviors more often than their neurotypical peers, with approximately 20% of ADHD children developing a chronic tic disorder. A tic is a sudden, repetitive motor movement or vocalization and may include:

• eye blinking
• mouth opening
• facial grimacing
• head movements
• shoulder shrugging
• throat clearing
• coughing
• sniffing
• barking
• snorting
• repeating parts of words or phrases.

Tics are involuntary and can be a single behavior or a combination of several behaviors.

Interestingly, there may be an overlapping neurological component of ADHD and tic disorders underlying their frequent co-occurrence. Abnormal levels of monoamine neurotransmitters (e.g., dopamine and norepinephrine) and a dysfunction in the communication between certain brain regions involved in movement, cognition, and behavior may contribute to disinhibition behaviors like the impulsivity in ADHD and the urges that prompt uncontrollable tic behaviors.

Tic disorders are neurodevelopmental disorders, and diagnosis is made when symptoms occur before the age of 18. Tic disorders can last a year or more or become severe enough to be diagnosed as Tourette syndrome. Tourette syndrome is a potentially lifelong condition characterized by frequent and numerous motor and vocal tics. Approximately half of children diagnosed with Tourette syndrome also have ADHD.

We never had my son evaluated; however, based on the diagnostic criteria, I don’t believe that he has Tourette syndrome. Interestingly, when the lead investigator of the ADHD study contacted a colleague who was studying Tourette syndrome and ADHD, my son didn’t qualify for that study either, since his tics weren’t severe.

In general, tics don’t cause a significant problem that requires treatment. However, if tics are severe enough, treatment may include ways to manage stress and anxiety through mindfulness or meditation, academic accommodations, parent training, family support, or medication. Currently, research data suggest that treating ADHD with stimulant medications will not increase tic behaviors. In cases of Tourette syndrome, Comprehensive Behavioral Intervention for Tics (CBIT) is the recommended treatment.

Stimming and ADHD

Stimming, or self-stimulating behavior, is another repetitive motor or vocal behavior associated with ADHD. All of us stim from time to time. My husband will point out when my leg shaking is vibrating the couch while we are watching a movie. Stims are purely sensation-seeking (tactile, auditory, visual, olfactory) and can be self-soothing or a way for our brains to stay engaged. I will frequently hear my son humming when he is trying to focus on a task. Stimming behaviors can include:

• hand flapping
• finger waving or wiggling
• foot tapping
• leg shaking
• rocking back and forth
• spinning
• head bobbing
• groaning
• screeching
• humming.

Fidgeting is a well-known behavior associated with ADHD; it helps with maintaining attention and may be considered stimming in this population. For example, children with ADHD have better focus when they manipulate something with their hands. Physically moving their hands to manipulate something provides tactile stimulation and helps to increase attention by affecting the levels of dopamine in certain brain areas.

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In contrast to tics, stimming may be beneficial for kids with ADHD. It might help them to manage in difficult situations, a way of relieving stress, tolerating boredom, expressing happiness, or coping with sensory overload.

Although my son’s tics have subsided (they usually do in adolescence and adulthood), they will sometimes occur when he is fatigued. I gently remind him of the behavior to make him aware, as I did when he was young, and within a day or two the behavior stops. More common is the humming I hear from his bedroom when he is trying to keep his ADHD brain engaged.