Historically, both generalized anxiety disorder (GAD) and obsessive-compulsive disorder (OCD) were considered anxiety disorders. Earlier editions of the Diagnostic and Statistical Manual of Mental Disorders (the DSM), a diagnostic reference guide used by clinicians to classify psychiatric conditions, grouped GAD and OCD within the same section. However, the fifth edition of the DSM published in May 2013, separated these diagnoses into different chapters.
One way to understand the difference between GAD and OCD (as well as the related conditions within that section) is to think about the behavioral component, or lack thereof, to each problem. Though individuals with GAD tend to worry a lot, they do not typically engage in compulsive, ritualistic behaviors to cope with their anxiety. People with OCD, however, commonly use repetitive behaviors (either physical or mental rituals called compulsions) to relieve stress caused by an obsession. Sometimes OCD compulsions result out of a belief that the behavior can keep a feared outcome from occurring.
An example of this would be handwashing excessively and ritualistically to prevent contamination. For people with full-blown OCD, compulsions take up a lot of their time (e.g., > 1 hour/day) and interfere with everyday responsibilities. Even if some behavioral correlate to the worry seen in GAD is present, like repeated reassurance-seeking from others, it is highly unusual for it to occur in a rigid, ritualized or compulsive manner.
The thought patterns characteristic of GAD also distinguish it from OCD. People with GAD tend to worry about real-life concerns; these topics are by-and-large appropriate to worry about, though the degree of worry is clearly excessive. Worries may be about major life issues – such as health, finances, or relationships – but they are also about many minor, day-to-day stresses that others would tend not to perceive as intensely – such as giving a work presentation or not being able to predict what one’s daily schedule will be. Pathological worry, the kind that meets the threshold for a diagnosis of GAD, is pervasive and uncontrollable and tends to involve a lot of catastrophizing or otherwise biased thinking.