Systematic Review of the Relationship of Premorbid Functioning and Psychosocial Outcomes in Longitudinal Studies of Early Psychosis

Background and Purpose: Schizophrenia is the 11^th leading cause of disability worldwide, and despite the success of antipsychotic medication in reducing clinical symptoms, psychosocial outcomes have remained stagnant for over 70 years (Fusar-Poli, 2017). Psychosocial outcomes are overall poor, but heterogeneity is present. The critical period hypothesis suggests that active psychotic symptoms cause the most neural damage during the first 2—5 years of illness leading to long-term disability in schizophrenia. Premorbid functioning, the ability to perform socially and academically before the onset of psychosis, is a well-known prognostic indicator, but is understudied in relationship to psychosocial outcomes. These patterns are highly heterogenous, and detailed examinations are likely to provide insight into predicting post-illness psychosocial functioning while highlighting strengths for interventions.

Methods: A systematic review was completed to identify all studies from 2007 until August 2019 that examined premorbid functioning to predict future psychosocial outcomes in early stage psychotic disorders. Inclusion criteria for the clinical samples were: majority of non-affective psychotic disorders, use of structured diagnostic system, and within three years of psychosis onset. Objective measures of psychosocial functioning and use the Premorbid Adjustment Scale (PAS) (Cannon-Spoor, 1982) to measure pre-illness functioning were required for standardization across studies.

Results: Initially, 426 articles were identified. After close review of study abstracts and articles a remaining 14 studies were determined to meet all criteria. Results were grouped by use of the PAS: domain of academic and/or social functioning or developmental periods of childhood, early and late adolescence, and young adulthood.

Premorbid Functional Domains: Eight out of ten included studies found significant relationships between premorbid functional domains and longitudinal post-illness psychosocial functioning. Social premorbid functioning was a consistent, robust predictor of global and social functional outcomes up to 5 years post-diagnosis. Academic premorbid functioning was a consistent predictor of occupational outcome up to 5 years post-diagnosis.

Premorbid Developmental Stage: Just four studies investigated functional changes across developmental stage as it relates to psychosocial outcomes with mixed findings. The importance of pre-illness functioning during late adolescence in predicting longitudinal post-illness outcome was replicated. Significant findings for functioning during childhood and early adolescence were also found.

Conclusions and Implications: These results signify the important relationship of pre-illness developmental functioning in predicting longitudinal psychosocial outcomes in psychotic disorders. Support for the detailed use of functional domain and developmental periods of the PAS in predicting longitudinal outcomes is provided. Implications of these results include highlighting the opportunity for preventative interventions prior to illness onset in psychotic disorders, known to cause severe and lasting disability. Predicting those with the worst psychosocial consequences of psychosis can inform prevention and intervention strategies. Targeting interventions for youth who may begin to deteriorate socially or academically, in middle or high school, could lessen the severity of psychosis and resulting psychosocial impairments. These results are particularly of interest to clinical social workers in youth focused practice and researchers motivated to promote recovery and reduce the suffering caused by severe mental illness.