Only when these traits become extreme, maladaptive, and cause clinically significant impairment in several aspects of ones life should a diagnosis of OCPD be considered. Personality change due to another medical condition. Obsessive–compulsive personality disorder must be differentiated from a personality change due to a medical condition, which affects the central nervous system, and may cause changes in behavior and traits. Substance use disorders. Substance use may cause the advent of obsessive-compulsive traits. It is necessary that this is distinguished from underlying and persistent behavior, which must occur when a person is not under influence of a substance. ICD-10
The World Health Organizations ICD-10 uses the term anankastic personality disorder (F60.5). At least four of the following must be present:

Feelings of doubt
Perfectionism
Excessive conscientiousness
Checking and preoccupation with details
Stubbornness
Caution
Rigidity
Insistent and unwelcome thoughts or impulses that do not attain the severity of an obsessive-compulsive disorder. Millons subtypes
In his book, Personality Disorders in Modern Life, Theodore Millon describes 5 types of obsessive–compulsive personality disorder, which he shortened to compulsive personality disorder. Comorbidity
Obsessive–compulsive disorder
OCPD is often confused with obsessive-compulsive disorder (OCD). Despite the similar names, they are two distinct disorders. Some OCPD individuals do have OCD, and the two can be found in the same family, sometimes along with eating disorders.The rate of comorbidity of OCPD in patients with OCD is estimated to be around 15–28%.
Restricted emotions and interpersonal functioning
Individuals with this disorder may display little affection and warmth; their relationships and speech tend to have a formal and professional approach, and not much affection is expressed even to loved ones, such as greeting or hugging a significant other at an airport or train station.They are extremely careful in their interpersonal interactions. They have little spontaneity when interacting with others, and ensure that their speech follows rigid and austere standards by excessively scrutinising it. They filter their speech for embarrassing or imperfect articulation, and they have a low bar for what they consider to be such. They lower their bar even further when they are communicating with their superiors or with a person of high status. Communication becomes a time-consuming and exhausting effort, and they start avoiding it altogether. Others regard them as cold and detached as a result.Their need for restricting affection is a defense mechanism used to control their emotions. They may expunge emotions from their memories and organize them as a library of facts and data; the memories are intellectualized and rationalized, not experiences that they can feel. This helps them avoid unexpected emotions and feelings and allows them to remain in control. They view self-exploration as a waste of time and have a patronising attitude towards emotional people. Interpersonal control
Individuals with OCPD are at one extreme of the conscientiousness continuum. While conscientiousness is a desirable trait generally, its extreme presentation for those with OCPD leads to interpersonal problems.