Disability in schizophrenia. Intrinsic factors and prediction of psychosocial outcome. An analysis of literature

Abstract

Many different factors, both related to the individual and illness ("intrinsic" factors) and to the environment ("extrinsic" factors), contribute in different ways to the development of disability. Basing on data of literature, this review focuses the main "intrinsic" factors predicting disability in schizophrenia. A systematic search on Mediline of all papers published during the period 1965-2001 was performed, using "schizophrenia", "outcome", "psychosocial outcome", "social disability" and "social adjustment" as key words. Only papers reporting specifically data about predictive factors and psychosocial outcome variables were considered; prospective follow-up studies were considered, but retrospective and cross-sectional studies were also taken into account when data deriving from prospective studies were inconsistent. Male sex predicts a higher disability among demographic factors; lower social and occupational adjustment are premorbid personality factors associated with higher disability; among factors related to illness, younger age at onset of illness, "nuclear", "non paranoid" and in particular "deficit" forms of schizophrenia seem to predict more disability. The latter seems to be predicted also by higher levels of negative symptoms and neuropsychological deficits; the role of depressive symptoms seems to be less supported by follow-up data; a continuous course of the illness predicts more disability, although some evidences show a progressive reduction of disability, at least in the long term. Disability shows a largely autonomous course respect to symptoms and has to be considered an independent parameter of outcome. Few intrinsic factors show a predictive role also in the long term.