Baseline factors predicting functional outcome after first-episode psychosis differ depending on whether the psychosis is caused by schizophrenia or another type of disorder, a team of researchers in Spain has found.
In a study that enrolled 95 people with first-episode psychosis who were followed up for 2 years, processing speed significantly predicted most functional outcome measures in patients who were found to have schizophrenia spectrum disorders.
Among people who were later diagnosed with bipolar disorder and other nonschizophrenic syndromes, however, visuospatial functioning (spatial orientation, motion detection, and stimulus perception) was the only significant predictor of functional outcomes.
For both groups together, higher levels of negative symptoms at baseline predicted worse functional outcomes, a finding consistent with those of many previous studies.
For the current study, published in the Journal of Psychiatric Research (2012;46:774-81), Javier Peña of the University of Deusto in Bilbao, Spain, and colleagues recruited 109 patients who were admitted to one psychiatric hospital’s first-episode psychosis unit.
After patients were stabilized for positive symptoms, each underwent an extensive neuropsychological evaluation and completed a battery of cognitive tests. Subjects’ functional outcomes were measured using three standardized exams: the WHODAS (WHO Disability Assessment Schedule), the GAF (Global Assessment of Functioning) scale, and the CGI (Clinical Global Impression) scale.
Of the 95 subjects who completed follow-up and were entered into analysis, 58 were ultimately diagnosed with schizophrenia syndromes and 37 were diagnosed with nonschizophrenia psychotic syndromes (including bipolar disorder, delusional disorder, and acute/transient psychosis).
The two subgroups were closely matched in terms of age (mean, 28 years in both groups at baseline), sex, vocabulary, and duration of untreated psychosis, although the schizophrenia group had fewer years of education and worse premorbid functioning. During the follow-up period, patients were treated with atypical antipsychotic medications at doses determined by their clinicians.
The authors found that low processing speed at admission significantly predicted most functional outcome measures at follow-up in patients with schizophrenia after investigators controlled for the effects of other variables. Processing speed explained 10% and 11% of the variance, respectively, on the CGI and GAF exams at the 2-year follow-up.
But for patients without schizophrenia, visuospatial functioning was found to be the best predictor of functional outcome, explaining 21%, 40%, and 21% of the variance on the CGI, GAF, and WHODAS measures for the subgroup at last follow-up.
The investigators noted as limitations of their research the fact that the variables they sought to test – sociodemographics, clinical variables, neuropsychological domains, premorbid functioning, and duration of untreated psychosis – were not necessarily the only variables that could affect functional outcomes after first-episode psychosis.
They also noted that "scarce attention" has been given to the question of whether the same factors serve as functional outcome predictors in both schizophrenic and nonschizophrenic patient groups. However, they said, their findings suggested that regardless of diagnosis, patients suffering a first psychotic episode could benefit from rehabilitation programs intended to improve neuropsychological function.
"Obtaining symptomatic improvement as the only treatment goal incurs the risk of overestimating patients’ overall functioning," the investigators wrote in their analysis.
The study was funded by the Spanish Ministry of Health and the Basque government. The authors stated that they had no conflicts of interest.