UC San Diego

Abstract Background: Recent studies have recognized that signs of functional disability in schizophrenia are evident in early phases of the disorder, and, as a result, can potentially serve as vulnerability markers of future illness. However, functional measures in the psychosis prodrome have focused exclusively on real-world accomplishment (ie, achievement), rather than on the skills required to carry-out a particular real-world function (ie, capacity). From this perspective capacity provides the foundation for what can actually be achieved. This is comparable to the comparison between IQ (capacity) vs grades at school (achievement). In one of the first reports of its kind, we introduced the Map task, a laboratory-based measure specifically designed to assess a young person’s basic capacity to carry-out age-appropriate skills that lead to independent community living (McLaughlin et al., 2016). Poor performance on the Map task was found to be predictive of conversion to psychosis, suggesting that functional capacity in the prodrome may represent a basic biologically-based vulnerability factor. Given that diminished functional capacity is often a key barrier to good functional outcomes in patients with schizophrenia, the current study sought to next evaluate whether deficits in capacity can also predict social and role (ie, academic) functioning in the prodrome. Methods: The Map task was administered to 609 subjects at Clinical High-Risk (CHR) for psychosis and 242 Healthy Controls (HCs) participating in the North American Prodrome Longitudinal Study (NAPLS2). Subjects were required to efficiently complete a set of specified errands in a fictional town. Results: Individuals with poor role functioning at study outcome had a lower Map efficiency score than those with good role outcome. In addition, the Map efficiency score predicted role functioning at outcome (OR = −0.971, 95% CI = 0.946 to 0.997; P = .027), even after accounting for conversion status, baseline IQ, and baseline role functioning). In contrast, the Map Efficiency score did not predict social outcome (OR = 0.989, 95% CI = 0.964–1.015; P = .416), supporting previous findings that social and role functioning are 2 distinct functional domains, with different developmental courses, with each having potential to provide predictors of long-term prognosis. Conclusion: Our findings support the notion that functional capacity may well represent a distinct vulnerability factor related to the multi-faceted long-term disability typically associated with schizophrenia. Poor performance on the Map task was significantly associated with impaired role functioning at study outcome, even after controlling for the contribution of conversion and intellectual performance. Thus, deficits in both role “capacity” and role “achievement” are present before the onset of the illness, and are not an artifact of psychosis onset or intellectual impairments.