The clinical utility of the tic-related obsessive-compulsive disorder diagnostic specifier

DSM Digest

Eapen et al. (2015) report that health-related quality of life is significantly negatively predicted by the co-occurrence of attention deficit hyperactivity disorder (ADHD), but not by the co-occurrence of obsessive-compulsive disorder (OCD). Considering that OCD is rated among the most distressing and disabling psychiatric disorders (Jayakumar et al., 2002), it would initially seem counter-intuitive. These findings have implications for our understanding of the relationship between OCD and tic disorders and for the clinical utility of the tic-related OCD specifier.

Tic disorders have been reported to co-occur at rates of 10–40% in patients with OCD (Gomes de Alvarenga et al., 2012). Tic-related OCD has been recognized as a diagnostic specifier in Diagnostic and Statistical Manual of Mental Disorders–Fifth Edition (DSM5). It is defined as a current or past history of a tic disorder, and it has been associated with several important clinical variables, such as earlier age of onset, male gender, greater likelihood of family members also having OCD and a poorer response to selective serotonin reuptake inhibitors (SSRIs) (Gomes de Alvarenga et al., 2012). Patients with OCD and co-occurring tic disorder are more likely to have other co-occurring disorders, e.g., ADHD (Wanderer et al., 2012). There may also be genetic links between OCD, tic disorders and ADHD as the three disorders co-occur in family members (Mathews and Grados, 2011).

The absence of an association between health-related quality of life and the co-occurrence of OCD in patients with tic disorders tells us not to expect each disorder to contribute to reduced health-related quality of life to a similar extent. Although there are similarities among the three disorders on neuroimaging and psychometric testing, there are also some differences. There are also differences in the course of the disorders (with OCD persisting into adulthood) and in their treatment (with each disorder being primarily treated by different classes of psychotropic medication, i.e., OCD with selective serotonin reuptake inhibitors, ADHD with stimulants and tic disorders with antipsychotics). Although the tic-related OCD specifier is clinically popular and has reasonable empirical support, the findings of Eapen et al. (2015) remind us that the three disorders do have distinct characteristics and that they are likely to vary in the extent to which they contribute to health-related quality of life.