age, such as cerebral infarction.
Development and Course
The development and course of  obsessive-compulsive and rela ted disorder due to another
medical condition generally follows the course of the underlying illness. 
Diagnostic Markers
Laboratory assessments and/or medical examinations are necessary to confirm the diag-
nosis of another medical condition.
Differential Diagnosis
Delirium. A separate diagnosis of obsessive-compul sive and related disorder due to an-
other medical condition is not given if the disturbance occurs exclusively during the
course of a delirium. Howeve r, a diagnosis of obsessive-compulsive and related disorder
due to another medical condition may be given in addition to a diagnosis of major neuro-
cognitive disorder (dementia) if the etiolo gy of the obsessive-compulsive symptoms is
judged to be a physiological consequence of the pathological process causing the dementia
and if obsessive-compulsive symptoms are a pr ominent part of the clinical presentation. 
Mixed presentation of symptoms (e.g., mood and obsessive-compulsive and related
disorder symptoms). If the presentation includes a mix of different types of symptoms,
the specific mental disorder due to another medical condition depends on which symp-
toms predominate in the clinical picture.
Substance/medication-induced obsessive-compulsive and related disorders. If there
is evidence of recent or pr olonged substance use (including medications with psychoac-
tive effects), withdrawal from a substance, or exposure to a toxin, a substance/medication-
induced obsessive-compulsive and related diso rder should be considered. When a sub-
stance/medication-induced ob sessive-compulsive and related disorder is being diag-
nosed in relation to drugs of abuse, it may be  useful to obtain a urine or blood drug screen