Adapted from the Obsessive-Compulsive Foundation website
Some disorders that closely resemble OCD and may respond to some of the same treatments are trichotillomania (compulsive hair pulling), body dysmorphic disorder (imagined ugliness), severe habit disorders such as nail biting or skin picking, and maybe stuttering. There are also several disorders that frequently co-exist with OCD (called comorbid conditions), such as depression. While they share superficial similarities, impulse control problems such as substance abuse, pathological gambling or compulsive sexual activity are probably not related to OCD in any substantial way.
Tic disorders: The most common conditions that resemble OCD and may be related to OCD are the tic disorders (Tourette syndrome and other motor and vocal tic disorders). Tics are involuntary motor behaviors, such as facial grimacing, or vocal behaviors, such as snorting, that often occur in response to an internal feeling of discomfort or an internal “itch”. More complex tics, like touching or tapping tics, may closely resemble compulsions. Tics and OCD occur together much more often when the OCD or tics begin during childhood. Many people with Tourette syndrome also have OCD.
Depression: Depression and OCD often occur together in adults, and less commonly, in children and adolescents. However, unless depression is also present, people with OCD are not generally sad or lacking in pleasure, and people who are depressed but do not have OCD rarely have the kinds of intrusive thoughts that are characteristic of OCD.
Eating disorders: The relationship between eating disorders (anorexia and bulimia) is complicated. Some people with eating disorders also have OCD symptoms, and some people with OCD have obsessions related to food. However, most people with OCD do not have an eating disorder, and most people with eating disorders do not have obsessions except for those related to food and body image, suggesting that these disorders are not directly related to each other. The exception to this is in children and adolescents, where symptoms of an eating disorder can present as part of OCD.
Post traumatic stress disorder: Although stress can make OCD worse, most people with OCD report that the symptoms can come and go on their own. OCD is easy to distinguish from a condition called post traumatic stress disorder, because OCD is not caused by a terrible event.
Schizophrenia: Schizophrenia, delusional disorders, and other psychotic conditions are usually easy to distinguish from OCD. Unlike psychotic individuals, people with OCD continue to have a clear idea of what is real and what is not. A substantial number of people with these disorders will also have OCD, however, maybe as many as 10-20%.
Bipolar disorder: Bipolar disorder, or manic depressive syndrome, is also easy to distinguish from OCD. The primary feature of bipolar disorder is severe mood swings, from extremely exalted or elevated for no reason, to depressed. Although everyone has mood swings, people with bipolar disorder have extreme shifts in their mood that lead them to excessive or reckless behaviors, or cause them to have psychotic symptoms. As many as 10% of people with bipolar disorder also have OCD.
Behavioral problems: In children and adolescents, OCD may worsen or cause disruptive behaviors, exaggerate a pre-existing learning disorder, cause problems with attention and concentration, or interfere with learning at school. In many children with OCD, these disruptive behaviors are related to the OCD and will go away when the OCD is successfully treated.
ADHD: Although attention deficit hyperactivity disorder (ADHD) is not directly related to OCD, some scientists and clinicians have noticed that some people with OCD have more symptoms of inattention and disorganization. Certain OCD symptoms can look like ADHD, for example, when an overwhelming and impossible need to do something “just right” causes someone not to do it at all, or when someone is repeating something over and over again in their head and thus can’t pay attention to anything else! In children and adolescents, OCD can be particularly difficult to distinguish from ADHD. Also, children and adults with Tourette Syndrome are more likely to have both OCD and ADHD. Often, treating the OCD successfully helps with the problems of inattention and disorganization. Unfortunately, some of the medications that are used to treat ADHD (such as stimulants) can make OCD symptoms worse, so in people who have both, a decision must be made about which is the most problematic.
Substance abuse: Individuals with OCD may have substance-abuse problems, sometimes as a result of attempts to self-medicate. Specific treatment for the substance abuse is usually also needed.
Pervasive developmental disorders: Children and adults with pervasive developmental disorders (autism, Asperger’s disorder) can be extremely rigid and compulsive, with stereotyped behaviors that somewhat resemble severe OCD. However, those with pervasive developmental disorders also have problems relating to and communicating with other people, which do not occur in OCD.
Personality traits: There are no specific personality traits that are associated with OCD, as far as we know. Only a small number of those with OCD have the collection of personality traits that is called obsessive compulsive personality disorder (OCPD). Despite its similar name, OCPD does not involve obsessions and compulsions, but rather is a personality pattern that involves a preoccupation with rules, schedules, and lists, perfectionism, an excessive devotion to work rigidity, and inflexibility. OCPD, unlike OCD, is often not uncomfortable or distressing for the person who has it. However, when people have both OCPD and OCD, the successful treatment of OCD often causes a favorable change in the person’s personality.