Why do some people experience sudden, uncontrollable movements or sounds known as tics?

Nature · Published 29 September 2026 Swipe more like this →

In short: Tics are repetitive, involuntary movements or vocalizations that often begin with a mounting physical tension. While they are frequently associated with childhood, these neurological phenomena can range from simple blinks to complex, coordinated behaviors. Understanding the urge behind them reveals a complex interplay between brain function and sensory experience.

Tics are defined as sudden, non-rhythmic movements or sounds involving discrete muscle groups. They are classified as either motor or phonic, and further categorized as simple or complex. Simple motor tics might include eye blinking or shoulder shrugging, while complex motor tics involve coordinated patterns like jumping or touching objects. Phonic tics, often preferred over the term vocal tics to acknowledge that vocal cords are not always involved, range from throat clearing to the utterance of taboo words, known as coprolalia.

A defining feature of tics is the premonitory urge—a sensory phenomenon described as a buildup of tension, similar to the need to sneeze or scratch an itch. This urge is often relieved only by performing the tic. While tics are considered semi-voluntary because they can be temporarily suppressed, this suppression typically results in mounting discomfort that eventually demands release. Interestingly, concentration on absorbing tasks can significantly reduce tic frequency, a phenomenon famously illustrated by a surgeon whose tics vanished while operating.

Tic disorders exist on a spectrum, with Tourette syndrome representing the more severe end. Diagnosis is based on symptom type and duration, as outlined in the DSM-5. Provisional tic disorder, the most common type, involves tics lasting less than one year, while persistent tic disorder and Tourette syndrome involve symptoms lasting longer than a year. Tourette syndrome specifically requires the presence of both motor and vocal tics. Although the exact cause remains unclear, researchers believe these conditions stem from changes in brain areas controlling movement and likely involve a genetic component.

Most tics are not serious and often improve or disappear as children mature, typically peaking between age eight and the teenage years. Treatment is only necessary if tics interfere with daily life or cause social or physical distress. Behavioral interventions, such as habit reversal therapy and comprehensive behavioral intervention for tics (CBiT), aim to teach individuals to manage or replace the urge to tic with intentional, competing movements.

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