The prognostic value of formal thought disorder following first episode psychosis.

BACKGROUND: Formal thought disorder (FTD) is associated with poor outcome in established psychotic illnesses and it can be assessed as a categorical or dimensional variable. However, its influence on functional outcome and hospitalisation patterns in early psychosis has not been investigated. We evaluated the relationship between FTD and these outcomes in a first episode psychosis (FEP) sample.

MATERIALS AND METHODS: A mixed diagnostic FEP cohort was recruited through an Early Intervention in Psychosis Service in Ireland. Participants were assessed at initial presentation and one year later with the MIRECC GAF to evaluate social and occupational functioning domains. Disorganisation (disFTD), verbosity (verFTD) and poverty (povFTD) dimensions of FTD were examined at both time points, as well as a unitary FTD construct. Analyses were controlled for demographic, clinical and treatment variables.

RESULTS: DisFTD was the only FTD dimension associated with functional outcome, specifically social functioning, on multivariate analysis (beta=0.13, P<0.05). The unitary FTD construct was not associated with functional outcome. DisFTD at FEP presentation predicted a greater number of hospitalisations (adjusted beta=0.24, P<0.001) and prolonged inpatient admission (adjusted OR=1.08, 95% CI 1.02-1.15, P<0.05) following FEP.

CONCLUSIONS: Longitudinal and dimensional evaluation of FTD has a clinical utility that is distinct from a cross-sectional or unitary assessment. Dimensions of FTD may map onto different domains of functioning. These findings are supportive of some of the changes in DSM-V with an emphasis on longitudinal and dimensional appraisal of psychopathology. Communication disorders may be considered a potential target for intervention in psychotic disorders.