Schizotypal Personality Disorder (Last Updated - 5/27/2003)
-subtype of Cluster A personality disorder
-char. by discomfort w/ social relationships (interpersonal awkwardness), thought discomfort & illusions
-odd preoccupations, speech & affect
-peculiar patterns of thinking (ideas of reference, persecutory illusions & magical thinking (lucky shoes or rituals)) -> differentiates
   schizotypal PD and schizoid PD
-more common among relatives w/ schizophrenia
-PD most resembling schizophrenia -> differentiate by the duration of symptoms:
   -Schizotypal (always) vs. Schizophrenia (more recently)
-decreased platelet monoamine oxidase (MAO) levels -> less social (platelet MAO levels correlate w/ social functioning)

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References:

1) First Aid for the USMLE Step 1. Bhushan et al. 2002. pg. 135.
2) Kaplan USMLE Step 2 Lecture Notes: Psychiatry and Epidemiology & Ethics. Gonzalez-Mayo A. and Shaner, R. 2002. pg. 74.
3) Kaplan & Sadock's Synopsis of Psychiatry. 8th Edition. Kaplan, H. and Sadock, B. 1998. pg. 783-784.