Definition of Schizoid personality disorder:

Schizoid personality disorder is a psychiatric condition characterized by a lifelong pattern of indifference to others and social isolation.

Causes, incidence, and risk factors:

Personality disorders are chronic behavioral and relationship patterns that interfere with a person's life over many years. The cause of schizoid personality disorder is unknown, and estimates of its incidence vary.

This disorder may be associated with schizophrenia and shares many of the same risk factors. However, schizoid personality disorder is not as profoundly disabling as schizophrenia, since it is not marked by hallucinations, delusions, or the complete disconnection from reality that occurs in untreated (or treatment-resistant) schizophrenia.