How Much Do We Know about Adult-onset Primary Tics? Prevalence, Epidemiology, and Clinical Features

BACKGROUND Tic disorders are generally considered to be of pediatric onset; however, reports of adult-onset tics exist in the literature. Tics can be categorized as either primary or secondary, with the latter being the larger group in adults. Primary or idiopathic tics that arise in adulthood make up a subset of tic disorders whose epidemiologic and clinical features have not been well delineated. METHODS Articles to be included in this review were identified by searching PubMed, SCOPUS, and Web of Science using the terms adult- and late-onset tics, which resulted in 120 unique articles. Duplicates were removed. Citing references were identified using Google Scholar; all references were reviewed for relevance. RESULTS The epidemiologic characteristics, clinical phenomenology, and optimal treatment of adult-onset tics have not been ascertained. Twenty-six patients with adult-onset, primary tics were identified from prior case reports. The frequency of psychiatric comorbidities may be lower in adults than in children, and obsessive compulsive disorder was the most common comorbidity. Adult-onset primary tics tend to wax and wane, occur predominantly in males, are often both motor and phonic in the same individual, and are characterized by a poor response to treatment. DISCUSSION We know little about adult-onset tic disorders, particularly ones without a secondary association or cause. They are not common, and from the limited data available, appear to share some but not all features with childhood tics. Further research will be important in gaining a better understanding of the epidemiology and clinical manifestations of this disorder.