Impaired Prefrontostriatonigral Functional Connectivity and Substantia Nigra Hyperactivity in Schizophrenia

Diagnostic and Symptom Quantification Procedures Masters or Doctoral-level clinicians conducted diagnostic evaluations and clinical ratings. Diagnoses were confirmed by consensus conference. Among a random sample of 10 subjects, the level of inter-rater agreement for diagnosis was high, with kappa = 0.86. Symptoms were quantified with the Brief Psychiatric Rating Scale (BPRS), Scale for the Assessment of Positive Symptoms (SAPS) and Scale for the Assessment of Negative Symptoms (SANS). Inter-rater agreements as quantified by intraclass correlation were 0.93, 0.96 and 0.81 respectively, p < 0.05 for all. The total SANS and SAPS scores were used to quantify negative symptoms and psychosis severity respectively. Level of disorganization was quantified by adding the following sub-scores: Conceptual Disorganization, Mannerism and Posturing, and Disorientation from the BPRS; Attention from SANS; Formal Thought Disorder, and Bizarre Behaviour from SAPS (1).