Relationship between neurocognition and functional recovery in first-episode schizophrenia: Results from the second year of the Oslo multi-follow-up study
Introduction
One of the great challenges of research in schizophrenia is understanding the heterogeneity of outcome following first-episode schizophrenia. Recovery is now acknowledged as a possible outcome, but there is still a lack of consensus on how recovery is defined, making it difficult to draw cross-study comparisons. Recovery in schizophrenia must be defined in ways that will promote replicable research with reliable outcome measures. Recently, more emphasis has been put on recovery as a subjective orientation or attitude (Torgalsbøen, 2005, Bellack, 2006, Lysaker and Roe, 2012) stressing the development of self-concept beyond the illness, of enjoyment of the world and of a sense of well-being, hope and optimism (Torgalsbøen, 2001). These subjective variables are important additions to the more objective measures of outcome (Torgalsbøen and Rund, 2010).
So far, there are very few studies investigating the rate of remission and full recovery in the crucial early phase of the illness, and with frequent assessment in multiple domains over a long period of time, using standardized operational definitions of full recovery (Liberman et al., 2002) including dimensions of functional recovery. Such dimensions may be freedom from psychotic symptomatology, productive activities in daily life such as having a job and an income, living independently, and having social relationships as well as romantic relationships (Harvey and Bellack, 2009). However, as pointed out by Bellack (2006), the criteria for full recovery do not address the person׳s satisfaction with life. Therefore, the criteria of recovery should be expanded to include a measure of quality of life as well as using a reliable measure of real life functioning (Cornblatt et al., 2007).
Although it has been established in numerous studies that cognitive impairment is present in schizophrenia (Mesholam-Gately et al., 2009, Zipursky et al., 2012, Lutgens et al., 2014), the evolution of the deficits over the course of the illness is still debated. Due to the many methodological problems in using cross-sectional design, among them sampling biases, follow-through longitudinal studies is the only design that will give decisive information on the neurocognitive trajectories in schizophrenia (Rund, 1998, Bora and Murray, 2014). Longitudinal studies of neurocognition in first-episode patients include an adequate and realistic baseline measure of neurocognitive performance, while at the same time minimizing the effect of confounding variables associated with chronicity. Results from a recent study (Torgalsbøen et al., 2014) using the MATRICS Consensus Cognitive Battery (MCCB) showed large effect size differences between patients and controls at baseline on every cognitive domain, as well as statistically significant improvements on overall cognitive function at 6 months follow-up for the patient group.
A review of the few longitudinal recent-onset studies of the relationship between neurocognition and outcome (Allott et al., 2011) indicates a predominance of negative findings, suggesting that the relationship between neurocognition and outcome may differ from the findings of cross-sectional studies of chronic patients. The association between cognition and outcome is claimed to be robust (Green and Harvey, 2014), but the results from the Allott review give a more nuanced picture for the recent-onset group. Furthermore, there are limitations of previous studies of the relationship between cognition and later functional outcome, such as: lack of control for potentially confounding variables and high attrition rate. Other longitudinal studies of first-episode patients have described the course of neurocognitive functioning, but not many have included a healthy control group and have conducted fewer assessments, for instance the 2 and 5-year follow-ups from the TIPS study (Rund et al., 2007, Barder et al., 2013a). Another limitation of earlier longitudinal studies of schizophrenia is the assessment of too few neurocognitive domains (Keshavan et al., 2003, Carlsson et al., 2006, Gonzales Blanch et al., 2010).
The importance of cognition for outcome in schizophrenia has been recognized with the development of the MCCB (Nuechterlein and Green, 2006), but so far, there are few studies using this cognitive battery for investigating the longitudinal prospective relationship between cognition and functional outcome in the early course of illness.
In our recent study of neurocognitive functioning, assessed by MCCB, and the influence of neurocognition on remission and real life functioning in first-episode schizophrenia (Torgalsbøen et al., 2014), we found that Attention/Vigilance and Verbal Learning significantly predicted remission status at 6 months follow-up, whereas Attention/Vigilance and Working Memory at baseline predicted the level of social and role functioning. These results are in line with research suggesting that some domains of cognition may be prognostic with respect to functional outcomes, particularly longer term outcomes (Allott et al., 2011).
The Oslo multi-follow-up study (Torgalsbøen et al., 2014) is designed to meet several of the above mentioned requirements. The MCCB (Nuechterlein and Green, 2006), measuring functioning across seven cognitive domains, allows us to determine whether specific cognitive domains predict specific functional outcomes, in line with the suggestion that not all types of cognition are equally important for navigating the real world (Green and Harvey, 2014). The most important cognitive domains for functional outcome seem to be executive function, verbal learning/memory, and attention. In addition, social cognition appears to be strongly related to community functioning. Social cognition refers to the processes by which people are able to navigate the social world, perceiving social cues and using them to guide interpersonal behavior (Fett et al., 2011).
While there are several studies of the relationship between neurocognition and functional outcome in first-episode psychosis (Bilder et al., 2000, Robinson et al., 2004, Addington et al., 2005, Dickinson et al., 2008), no single study has used both published criteria for remission (Andreasen et al., 2005) and full recovery (Liberman et al., 2002, Torgalsbøen and Rund, 2002) and the MCCB to examine the association between baseline neurocognitive function in first-episode schizophrenia and later remission and/or full recovery. The MCCB allows facilitated comparisons across studies, and the consensus based criteria of symptom remission and full recovery permit a more reliable estimate of the degree of both symptom improvement and functional recovery. In this study, first-episode schizophrenia patients are assessed at several follow-up points. This procedure enables us to investigate if the duration criteria of sustained remission and full recovery are fulfilled (Liberman et al., 2002, Andreasen et al., 2005), and to study neurocognitive change and the relationship between neurocognition and functional outcome. It offers an important contribution to present knowledge, since the sample is assessed on multiple cognitive domains as well as symptom ratings every year over a long time-period (10 years). The course of neurocognitive functioning in both the patient and the healthy control sample is investigated. The study is ongoing, and here we present the results from the 2-year follow-up assessment. The current study addresses three research questions:
- 1.
How many first-episode schizophrenia patients meet comprehensive criteria for remission and full recovery at 2-year follow-up?
- 2.
Does the level of neurocognitive functioning in young adults with schizophrenia change from baseline to the 2-year follow-up assessment compared to that of the healthy control group?
- 3.
Is cognition significantly and independently predictive of functional recovery after controlling for non-cognitive baseline factors?
Section snippets
Subjects
Over a period of 4 years (2007–2011) 28 patients with first-episode schizophrenia were referred to the study. The demographic and clinical characteristics of the participants are presented in Table 1. The patients were recruited from mental health service institutions in the Oslo area. Shortly after admittance, their treating clinicians referred them to the project. Inclusion criteria were age>18 years; the first episode of mental illness within the spectrum of schizophrenia and psychosis
Results
At follow-up 20 patients (80.0%) were in remission and 4 (16.0%) fulfilled the criteria for full recovery, i.e. sustained improvement in both symptoms and social/vocational functioning for 2 years or longer. Four patients were partially recovered (i.e. fulfilling all but one criteria of full recovery). Demographic, social and functional characteristics of recovered and remitted patients are shown in Table 3. For the whole sample, PANSS scores are significantly reduced from baseline to follow up
Discussion
The vast majority of subjects showed significant improvement in symptoms, with a smaller proportion of individuals demonstrating adequate social/interpersonal functioning and good role functioning. In addition, they were relatively free of psychopathology and reported a high degree of satisfaction with life.
The amount of patients fulfilling remission criteria is in line with results from a recent review showing that first-episode samples display higher frequencies of remission than
Conflict of interest
None.
Acknowledgments
The authors gratefully acknowledge the contribution of the participants to this study.
This project was funded by the Department of Psychology, University of Oslo.
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