Patients participating to neurobiological research in early psychosis: A selected subgroup?
Introduction
Exciting or demanding biomedical investigations may attract a specific subgroup of volunteers and conclusions derived from such research may present serious limitations (Gustavsson et al., 1997). Referral questions, motivation and ability to consent may induce selection bias of patients consenting to participate in psychiatric neurobiological research. Moreover many of such studies are based on relatively small number of participants. This might contribute to the lack of consensus between studies and affect findings' generalisation. Selection bias may thus fuel the so-called “replicability crisis” (Barch and Yarkoni, 2013; Gorgolewski and Poldrack, 2016; Tackett et al., 2016).
A study investigating the willingness to take part in research consecutively to psychiatric admission reported high (>70%) readiness to participate, and found that rather than remuneration or other factors, altruistic motivations such as the wish to help science to progress and to allow patients to benefit from better treatments were the most frequent (Zullino et al., 2003). Selection bias is difficult to investigate because data on patients who did not participate are typically not available. Data stemming from prospective clinical cohort studies can offer a context where such a limitation may be overcome. The goal of our study was to compare the characteristics, within a clinical cohort of patients with early psychosis treated at the Treatment and early Intervention in Psychosis Program (TIPP), of patients who consented to neurobiological research with those who didn't.
Section snippets
Participants
TIPP is a specialized early psychosis program at the Department of Psychiatry in Lausanne University Hospital, Switzerland. Inclusion criteria are age between 18 and 35, living in catchment area (population about 300,000) and meeting criteria for psychosis, as defined by the ‘psychosis threshold’ subscale of the Comprehensive Assessment of At Risk Mental States scale (Yung et al., 2005). The program has been detailed elsewhere (Baumann et al., 2013). Patients with psychosis related to
Results
Out of 284 patients, 95 (33.45%) consented to the biomarker study and 189 (66.55%) didn't.
Discussion
Globally, our results suggest that, in our cohort, patients included in a biomarker study were globally representative of all patients treated in our program and that our results can reasonably be generalised to other patients with early psychosis. While this need to be replicated in other samples, this observation is important when considering the important role translational research may play in advancing our understanding of the basic mechanisms linked to severe mental disorders. However,
Conclusion
Our study showed that, although it implied an important number of assessments, patients of our cohort who participated to our biomarker study were globally representative of patients in the entire cohort. While this needs to be replicated in other samples and the few differences identified should be systematically evaluated in future studies, this suggests that findings from neurobiological studies are likely to have a good validity and can be generalised to other patients with early psychosis.
Contributors
PG, PB and PC designed this study. PG analyzed and interpreted the data. PG, PB and RJ drafted the first version of the manuscript. PC and KD critically revised the manuscript for important intellectual content. All authors read and approved the final manuscript.
Conflict of interest with respect to the study and manuscript
The authors declare no conflict of interest in relation to the subject of the study.
Role of the funding source
This study was supported by the Swiss National Science Foundation (#320030_122419 to P.C.), by the FNS SYNAPSY (#320030‑158776) and institutional funding. PSB was financially supported by Leenaards Foundation.
Acknowledgment
We wish to thank the case managers from the TIPP Program for their invaluable work for collecting this data over the years. We also express our gratitude to all patients for their enduring participation.
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