654 Personality Disorders
they lack emotion. Their lives sometimes se em directionless, an d they may appear to
“drift” in their goals. Such individuals ofte n react passively to adverse circumstances and
have difficulty responding appropriately to im portant life events. Because of their lack of
social skills and lack of desire for sexual experiences, individuals with this disorder have
few friendships, date infreque ntly, and often do not marry. Occupational functioning may
be impaired, particularly if interpersonal involvement is required, but individuals with
this disorder may do well when they work un der conditions of soci al isolation. Particu-
larly in response to stress, individuals with this disorder may experience very brief psy-
chotic episodes (lasting minutes to hours) . In some instances, schizoid personality
disorder may appear as the pr emorbid antecedent of delusional disorder or schizophre-
nia. Individuals with this disorder may so metimes develop major depressive disorder.
Schizoid personality disorder most often co-occurs with schi zotypal, paranoid, and avoid-
ant personality disorders.
Prevalence
Schizoid personality disorder is uncommon in clinical settings. A prevalence estimate for
schizoid personality based on a probability su bsample from Part II of the National Co-
morbidity Survey Replication suggests a pr evalence of 4.9%. Data from the 2001–2002
National Epidemiologic Survey on Alcohol and Related Conditions suggest a prevalence of
3.1%.
Development and Course
Schizoid personality disorder may be first apparent in childhood  and adolescence with
solitariness, poor peer relationships, and underachievement in school, which mark these
children or adolescents as different and make them subject to teasing.
Risk and Prognostic Factors
Genetic and physiological. Schizoid personality disorder may have increased preva-