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ICOSR 2013—Is the Psychosis Continuum for Real?

19 May 2013

As part of our ongoing coverage of the 2013 International Congress on Schizophrenia Research (ICOSR), held 21-25 April in Colorado Springs, Colorado, we bring you session summaries from some of the Young Investigator Travel Award winners. For this report, we thank Helen Fisher of the Institute of Psychiatry, London, U.K.

20 May 2013. The symposium "Is the Psychosis Continuum for Real? The Cognitive, Environmental, and Neural Correlates of ‘Real’ Psychotic Experiences in the General Population" sought to further increase awareness of the presence of psychotic symptoms amongst individuals who do not meet diagnostic criteria or require psychiatric care for a psychotic disorder. Numerous studies have now shown that a substantial minority of children and adults in the general population report having psychotic-like experiences (see Kelleher et al., 2012, for a review), while a smaller proportion are likely to have clearly defined psychotic symptoms, and even fewer will be diagnosed with a psychotic disorder during their lifetime, leading to the postulation of a quantitative continuum of psychosis (van Os et al., 2009). For most individuals, subclinical psychotic-like experiences and symptoms appear to be transitory (Cougnard et al., 2007), and it is debatable as to whether they index risk only for psychotic disorders (Fisher et al., 2013; Murray and Jones, 2012; Werbeloff et al., 2012). Nonetheless, psychotic symptoms do persist in some individuals seemingly without their experiencing any palpable distress or requiring psychiatric care (Linscott and van Os, 2013).

The speakers in this symposium examined various ways in which this non-clinical group with psychotic symptoms can be differentiated from individuals with a clinical diagnosis of psychosis. Such comparisons provide promising opportunities to unravel psychosis etiology. By gaining greater insight into why only some individuals with anomalous or unusual experiences develop a need for psychiatric care, it may eventually be possible to halt, or at least reduce the likelihood, of an individual moving along a hypothesized continuum to a full-blown, clinically relevant psychotic disorder.

Iris Sommer, UMC Utrecht, the Netherlands, perfectly set the scene for the symposium by showing a video in which a man without any psychiatric diagnosis described the voices that he has heard for many years. This video clip instantly drew our attention to clear differences in his experience and interpretation of his voices than tend to occur for patients seen in a psychiatric clinic. Namely, the voices he heard mainly said positive things to him, he was not distressed by their occurrence, and he did not provide a delusional interpretation of their presence; rather, he seemed to accept that they were "just there." This comfortableness with ambiguity and lack of a clearly formed belief about why the voices occurred seems to be a key distinguishing feature of non-clinical from clinical voice hearers and fits with research from Smeets et al. (Smeets et al., 2012) that suggested the combination of hallucinations and delusions increased the risk of developing a psychotic disorder. The good social and occupational functioning of the man in the video also set him apart from individuals requiring treatment for a psychotic disorder. However, Sommer also presented findings demonstrating overlap in the brain regions activated during auditory hallucinations in non-clinical and clinical individuals (Diederen et al., 2012), suggesting that the underlying phenomenon may be similar in both groups, but the important difference could be the interpretation of the experience.

The contrasting appraisals of non-clinical and clinical individuals with psychotic symptoms were also the focus of the presentation by Emmanuelle Peters, Institute of Psychiatry, London, U.K. In keeping with cognitive models of psychosis (Garety et al., 2001, 2007), she advocated that the way individuals appraised anomalous experiences, such as hearing or seeing things that other people could not, was a crucial factor in determining whether they developed psychotic symptoms requiring psychiatric care or continued to have non-distressing psychotic experiences. Lovatt et al. (Lovatt et al., 2010) found that non-clinical individuals tended to account for their psychotic experiences by using psychological, spiritual, and normalizing explanations, while the diagnosed group were more likely to think that "other people" were causing their psychotic experiences, and believed they were in danger or being threatened. Peters suggested this more paranoid worldview might have been brought about by exposure to interpersonal trauma (Lovatt et al., 2010) and is likely to result in greater distress (Gaynor et al., 2013) and, thus, subsequent need for psychiatric care.

However, Kirstin Daalman, UMC Utrecht, the Netherlands, presented data that contradicted part of Peters’ hypothesized pathway. Daalman et al. (Daalman et al., 2012) have found that both non-clinical and clinical groups with auditory verbal hallucinations are more likely to report a history of interpersonal forms of trauma in childhood when compared to controls. Instead, it was the emotional valence of the voices that differed between the groups, with non-clinical individuals experiencing voices that were reassuring, and those with a psychotic disorder more frequently reporting their voices as threatening. One possibility is that exposure to prior trauma or revictimization in adulthood might have adversely impacted on the worldview held by those individuals who went on to require psychiatric care. Clearly, more exploration of the full etiological pathway to developing clinically relevant psychosis is required.

The final presenter, Leslie Horton, University of Pittsburgh, Pennsylvania, presented research on schizotypy, which Sommer had earlier suggested lies between psychotic-like experiences and psychotic disorder on the psychosis continuum. Indeed, Horton drew our attention to research by Kwapil et al. (Kwapil et al., 2008), which indicated that both positive and negative forms of schizotypy are associated with impaired functioning. Nonetheless, she suggested that these types of schizotypy may have different etiologies and outcomes. Horton reported that individuals with positive schizotypy did not tend to have schizoid symptoms (Barrantes-Vidal et al., 2013) but were more likely than those with negative schizotypy to feel suspicious or maltreated in the moment and also experience more psychotic-like symptoms when under stress when compared to those with low levels of schizotypy (Barrantes-Vidal et al., unpublished). By contrast, individuals with negative schizotypy tended to have no thoughts or feelings in the moment when assessed using experience sampling methodology. Further work is required to explore the outcomes of individuals with positive and negative schizotypy, and they may also represent a useful group for exploring the etiology of psychotic disorders without the confounding effects of medication and chronic illness.

Tony David, Institute of Psychiatry, London, U.K., rounded off the symposium by reflecting on the possibility of various continua with perhaps the continuum of positive to negative valence of psychotic symptoms being of particular importance. He also raised the interesting question of whether individuals situated at one point on a psychosis continuum could move up or down the continuum. Finally, he cautioned about the need to consider directionality more carefully and explore further the role of dissociation and the possible link between appraisal and biological experience.

The debate concerning the presence of a continuum of psychosis rumbles on (see Linscott and van Os, 2013, for a recent update), with potentially important implications for future editions of DSM and ICD. However, the existence of individuals in the general population who have psychotic symptoms but do not require psychiatric care appears to be very much a reality.—Helen Fisher.