• Hamilton Depression Rating Scale [ Time Frame: Measured at Week 6 ] [ Designated as safety issue: No ]
• Positive and Negative Symptom Scale [ Time Frame: Measured at Week 6 ] [ Designated as safety issue: No ]
• Clinical Global Impression Scale [ Time Frame: Measured at Week 6 ] [ Designated as safety issue: No ]

• Hamilton Depression Rating Scale
• Positive and Negative Symptom Scale
• Clinical Global Impression Scale (all measured at Week 8)

This study will determine the effectiveness of guanfacine in improving symptoms of schizotypal personality disorder.

Schizotypal personality disorder is a psychiatric condition that is characterized by deficiencies in interpersonal relationships and disturbances in thought patterns, appearance, and behavior. This disorder is different from schizophrenia. While some of the symptoms of the two disorders are similar, such as the tendency to have unusual beliefs and behaviors, people with schizotypal personality disorder do not experience hallucinations and are not significantly disconnected from reality, both of which are signature symptoms of schizophrenia. Guanfacine is a drug that is often used to treat high blood pressure and attention deficit hyperactivity disorder. There is evidence that guanfacine enhances cognition and diminishes impulsivity. This study will determine the effectiveness of guanfacine in improving symptoms of schizotypal personality disorder.

Participants in this 6-week, double-blind study will be randomly assigned to receive either guanfacine or placebo. Participants receiving guanfacine will remain on the drug for the duration of the study. The other participants will receive placebo for the duration of the study. Guanfacine dosages will not exceed 2 mg per day. All participants will report to the study site weekly for assessments of vital signs, study compliance, medication side effects, and psychological symptoms. Additional cognitive testing will be performed at week 6. Upon study completion, patients will return for a follow-up assessment.

• Schizotypal Personality Disorder
• Personality Disorders

• Drug: Guanfacine
• Drug: Placebo

• Experimental: Participants will take guanfacine.
• Placebo Comparator: Participants will take placebo.

Inclusion Criteria:

• Meets DSM-IV criteria for schizotypal personality disorder (or meets full criteria except for one) OR meets DSM-IV criteria for avoidant personality disorder (without schizotypal, paranoid, and schizoid comorbidities and fewer than two schizotypal criteria) and shows impairment of cognitive functioning according to set markers
• In good psychological health
• Medication-free for at least 2 weeks prior to study entry
• Personality disorder holds primary responsibility for participant's functional impairment (other Axis I disorders will not be criteria for exclusion as long as they are transient and were preceded by the personality disorder diagnosis)
• Control subjects must have no current Axis I or II diagnosis and no family history of psychotic disorders

Exclusion Criteria:

• Meets DSM-IV or RDC criteria for schizophrenia, any schizophrenia-related psychotic disorder, or bipolar disorder
• Significant neurological disease
• Current drug or alcohol abuse or dependence in the last 6 months
• Current major depression
• Vision <20/40, IQ<80, or 20% above ideal weight