238 Obsessive-Compulsive and Related Disorders
Specifiers
Many individuals with obsessive-compulsive disorder (OCD) have dysfunctional beliefs.
These beliefs can include an inflated sense of responsibility and the tendency to overesti-
mate threat; perfectionism and intolerance of uncertainty; an d over-importance of thoughts
(e.g., believing that having a fo rbidden thought is as bad as acting on it) and the need to
control thoughts. 
Individuals with OCD vary in the degree of insight they have about the accuracy of the
beliefs that underlie their obsessive-compulsive symptoms. Many individuals have good or
fair insight  (e.g., the individual believes that the house definitely will not, probably will not,
or may or may not burn down if the stove is not checked 30 times). Some have poor insight
(e.g., the individual believes that the house w ill probably burn down if the stove is not
checked 30 times), and a few (4% or less) have absent insight/delu sional beliefs  (e.g., the in-
dividual is convinced that the house will burn down if the stove is not checked 30 times).
Insight can vary within an individual over the course of the illness. Poorer insight has been
linked to worse long-term outcome.
Up to 30% of individuals with OCD have a lifetime tic disorder. This is most common
in males with onset of OCD in childhood. Thes e individuals tend to differ from those with-
out a history of tic disorders in the themes of their OCD sy mptoms, comorbidity, course,
and pattern of fam ilial transmission. 
Diagnostic Features
The characteristic symptoms of OCD are the pr esence of obsessions and compulsions (Cri-
terion A). Obsessions  are repetitive and persistent thoughts (e.g., of contamination), images