in Norwegian samples to 4.6% in a U.S. commu nity sample. The prevalence of schizotypal
personality disorder in clinical populations seems to be infrequent (0%–1.9%), with a
higher estimated prevalence in the general population (3.9%) found in the National Epi-
demiologic Survey on Alco hol and Related Conditions.
Development and Course
Schizotypal personality disorder has a relative ly stable course, with only a small propor-
tion of individuals going on to develop sc hizophrenia or another psychotic disorder.
Schizotypal personality disorder may be firs t apparent in childhood and adolescence with
solitariness, poor peer relationships, social anxiety, underachievement in school, hyper-
sensitivity, peculiar thoughts and language, an d bizarre fantasies. These children may ap-
pear “odd” or “eccentric” and attract teasing. 
Risk and Prognostic Factors
Genetic and physiological. Schizotypal personality disord er appears to aggregate fa-
milially and is more prevalent among the firs t-degree biological relatives of individuals
with schizophrenia than among the general po pulation. There may also be a modest in-
crease in schizophrenia and other psychotic disorders in the relatives of probands with
schizotypal personality disorder.
Cultural-Related Diagnostic Issues
Cognitive and perceptual distortions must be evaluated in the context of the individual’s
cultural milieu. Pervasive cultur ally determined characteristic s, particularly those regard-
ing religious beliefs and rituals, can appear to be schizotypal to the uninformed outsider
(e.g., voodoo, speaking in tongues, life beyo nd death, shamanism, mind reading, sixth
sense, evil eye, magical beliefs related to health and illness).