Positive symptoms of schizophrenia are inversely correlated with ability to function

Key message: Increase in positive symptoms is directly correlated with a reduction in functional capacity. The correlation between positive symptoms and depression is predictive of impairment in real-world performance measures (as measured by interpersonal skills, community activities, work skills)

Background

• Cross-sectional data was examined from a study of the course of neuropsychological and adaptive life skills patients with schizophrenia (age 50–85) (N=78).
• Functional capacity was examined with a performance-based measure (UCSD Performance-Based Skills Assessment), and case managers rated real-world adaptive functions (i.e., interpersonal skills, work skills, and community activities).
• Real-world functional performance was examined using the Specific Level of Function Scale, which is a 43-item caretaker report of a patient’s behavior and functioning across the following domains: physical functioning (e.g., vision, hearing), personal care skills (e.g., eating, grooming), interpersonal skills (e.g., initiating, accepting and maintaining social contacts; effectively communicating), social acceptability (e.g., absence of verbal and physical abuse, absence of repetitive behaviors), community activities (e.g., shopping, using telephone, paying bills, use of leisure time, use of public transportation) and work skills (e.g., employable skills, level of supervision, punctuality).
• Severity of schizophrenia symptoms was assessed by the Positive and Negative Syndrome Scale (PANSS), which was completed after a structured interview.
• Self-reports of depression were obtained from the patients by using the second edition of the Beck Depression Inventory.
• Confirmatory path analyses were conducted to determine which of the variables predicted or mediated the relationship with the functional outcome domains from the Specific Level of Function Scale. The goodness of fit of these models was tested statistically and compared with several comparison models. In these analyses, the Specific Level of Function Scale domains were used as the outcome variables.

Reference:
Bowie CR, et al. Am J Psychiatry. 2006; 163 (3): 418–25.