der must be distinguished from personality change due to another medical condition, in
which the traits that emerge ar e attributable to the effects of another medical condition on
the central nervous system. 
Substance use disorders. Schizotypal personality disorder  must also be distinguished
from symptoms that may develop in a ssociation with persistent substance use.
Other personality disorders and personality traits. Other personality disorders may
be confused with schizotypal personality diso rder because they have certain features in
common. It is, therefore, important to distin guish among these disorders based on differ-
ences in their characteristic features. However, if an individual has personality features
that meet criteria for one or more personality disorders in addition to schizotypal person-
ality disorder, all can be diagnosed. Although paranoid and schizoid personality disor-
ders may also be characterized by social de tachment and restricted affect, schizotypal
personality disorder can be distinguished fr om these two diagnoses by the presence of
cognitive or perceptual distortions and marked eccentricity or oddn ess. Close relation-
ships are limited in both schizotypal person ality disorder and avoidant personality dis-
order; however, in avoidant personality disorder an active desire for relationships is
constrained by a fear of rejection, whereas in schizotypal personality disorder there is
a lack of desire for relationships and persis tent detachment. Indivi duals with narcissistic
personality disorder may also display suspic iousness, social withdrawal, or alienation,
but in narcissistic personality disorder these qualities derive primarily from fears of hav-
ing imperfections or flaws revealed. Individu als with borderline personality disorder may
also have transient, psychotic-like symptoms, but these are usually more closely related to