Tic Disorders: Introduction | Symptoms and Comorbidity | Differential Diagnosis | Epidemiology | Genetics | Neuroanatomy and Neurophysiology | Assessment | Treatment | Advocacy | Research Directions | Summary Points | References
Tics are sudden, quick, repetitive, stereotyped, "relatively
involuntary" muscle contractions that can occur in any
part of the body. Tic disorders are highly prevalent in children
and adolescents but cause severe impairment in only a small minority.
However, tic disorders also are model neuropsychiatric conditions
that provide a unique window into the interplay of genetic risk,
psychology, experience, and environment. Exploring tic disorders
has led to a deeper understanding of neural pathways and circuits
in the brain that subserve sensory and motor function, linking the
frontal lobes, the striatum, and thalamus. The study of tic disorders
has increased our knowledge of the relationship between cognition
and motor activity and illuminated the role of striatum in motor
planning and execution. Treatments now include interventions that
draw directly on this preclinical and clinical work.