588 CHAPTER 13
The DSM-IV-TR explicitly notes that cognitive and perceptual distortions may
occur as part of culturally sanctioned or religious rituals or practices, and these
should be distinguished from symptoms of schizotypal personality disorder. Ex-
amples include voodoo experiences, mind reading, and receiving “the evil eye”
(Campinha-Bacote, 1992; Paniagua, 2001).Understanding Odd/Eccentric Personality Disorders
The odd or eccentric elements of Cluster A personality disorders are less intense
manifestations of features of schizophrenia (Chapter 12): Paranoid personality
disorder involves paranoid beliefs; schizoid personality disorder involves fl at af-
fect and a detachment from others; and schizotypal personality disorder involves
cognitive alterations similar to those that arise in schizophrenia—delusions and
unusual perceptions. Schizotypal personality disorder is the most thoroughly re-
searched among the odd/eccentric personality disorders; thus, in this section we
focus predominantly on the neuropsychosocial factors that give rise to this particu-
lar disorder but also include information about the other odd/eccentric personality
disorders where appropriate.Neurological Factors in Odd/Eccentric Personality Disorders
Most of the neurological factors that contribute to schizophrenia have also been
found to contribute to schizotypal personality disorder: genes and prenatal environ-
ment, such as maternal illness and malnourishment, and birth complications (Raine,
2006; Torgersen et al., 2000). In both disorders, researchers have documented ab-
normalities in brain structure (in the frontal and temporal lobes, the thalamus, and
the hippocampus) and abnormalities in neural function (activity of dopamine, se-
rotonin, and glutamate). These abnormalities are generally not as severe in people
with schizotypal personality disorder as in people with schizophrenia (Buchsbaum
et al., 2002; Siever & Davis, 2004).
Genes play a role in all Cluster A personality disorders (paranoid, schizoid, and
schizotypal): First-degree relatives of patients with Cluster A personality disorders
are more likely to develop a schizophrenia-related disorder than are people who are
not related to such patients (Chang et al., 2002; Siever & Davis, 1991). This makes
sense given that schizophrenia shares some symptoms with each of the odd/ eccentric
personality disorders. Additional evidence that genes play a role is the fact that the
rates of schizotypal personality disorder are higher among family members of peo-
ple with schizophrenia than among the general population (Siever & Davis, 2004;
Tienari et al., 2003).Psychological Factors in Odd/Eccentric Personality Disorders
Like people with schizophrenia, those with schizotypal personality disorder tend
to have specifi c cognitive defi cits. These include problems with attention (distin-
guishing relevant from irrelevant stimuli), memory, and executive function (used
in problem solving, planning, and judgment) (Voglmaier et al., 2000). According
to Beck and colleagues (2004), schizotypal personality disorder is unusual among
the personality disorders in that the primary distortions are in mental processes
(e.g., perceptions) rather than in mental contents. However, problems with so-
cial interactions can arise from the cognitive defi cits: People with this personality
disorder tend to have an impaired theory of mind—as refl ected by diffi culty rec-
ognizing emotions in others (Waldeck & Miller, 2000) and taking another’s
point of view or recognizing another’s mental state (Langdon & Coltheart, 2001).
Although people with schizotypal personality disorder have cognitive defi cits, they
generally have better cognitive skills than do people with schizophrenia (Trestman
et al., 1995).
In addition, core maladaptive beliefs and strategies of people with each of the
odd/eccentric personality disorders may differ (see Table 13.10), but all these patientsP SN