The neurophenomenology of early psychosis: An integrative empirical study
Introduction
In recent years there has been considerable interest in the construct of minimal self-disturbance as a phenotypic marker of the schizophrenia spectrum (Maj, 2012, Nelson et al., 2014, Nelson and Raballo, 2015, Parnas and Henriksen, 2014), particularly with regard to its utility in nosological, aetiological and prediction research. The ‘minimal self’, aka ‘basic’ or ‘core’ self, widely discussed in neuroscience, philosophy of mind, and phenomenology, refers to the pre-reflective and immediate consciousness of action, experience, and thought. Two nested concepts can be identified as constituting this aspect of selfhood: sense of ownership/mine-ness and sense of agency (Gallagher, 2011). While the former refers to perceiving my body, perceptions, and thoughts as my own, the latter refers to experiencing myself as the source of my actions and their consequences. These are generally implicit aspects of a normal sense of minimal self and facilitate interactions with others/the world (Zahavi, 2003). A fragile or unstable minimal self can manifest in a variety of anomalous subjective experiences including:
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disturbed sense of ownership of moment-to-moment experience, e.g., the sense that my thoughts or body parts are not my own;
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disturbed agency, e.g., the sense of not being the source or cause of my actions;
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unstable ‘first-person’ perspective, associated with states of depersonalisation, e.g., feeling as though I am watching myself from a distance or somehow alienated from my own body;
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difficulty forming a continuous and coherent identity, e.g., feeling anonymous or without a stable perspective and identity over time.
Such experiences frequently result in perplexity, disorientation, and difficulties with social functioning and understanding, also referred to as a lack of common sense (Blankenburg, 2001), and are profoundly distressing (Nelson et al., 2009). Minimal self-disturbance can intensify and crystallise over time into full-blown positive and negative psychotic symptoms (Davidsen, 2009, Møller and Husby, 2000, Nelson et al., 2012, Parnas, 1999, Parnas, 2000, Sass and Parnas, 2003).
The main measure of minimal self-disturbance is the Examination of Anomalous Self-Experience (EASE) (Parnas et al., 2005a, Parnas et al., 2005b). Empirical findings using the EASE and pre-EASE scales indicate that minimal self-disturbance:
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characterises schizophrenia spectrum disorders independent of presence of frank psychotic symptoms, i.e., is present in schizotypal disorder as well as in psychotic schizophrenia-spectrum disorders (Handest and Parnas, 2005, Nordgaard and Parnas, 2014, Parnas et al., 2005a, Parnas et al., 2005b);
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correlates moderately with clinical features of schizophrenia (Nordgaard & Parnas, 2014);
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is more prominent in schizophrenia than in psychotic disorders outside the schizophrenia spectrum, such as bipolar disorder with psychosis (Haug et al., 2012, Nordgaard and Parnas, 2014, Parnas et al., 2003);
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correlates moderately with prodromal symptoms in non-psychotic adolescents (Koren et al., 2016, Koren et al., 2013, Raballo et al., 2016) and predicts future onset of schizophrenia spectrum disorders in non-psychotic clinical populations (Parnas et al., 2011) and in clinical high risk for psychosis patients (Nelson et al., 2012);
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increases in relation to schizophrenia symptom expression in a large genetic linkage sample (Raballo and Parnas, 2011, Raballo et al., 2011) and in relation to severity of psychotic diagnostic staging (Raballo et al., 2018);
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is related to suicidality (Haug et al., 2012, Skodlar and Parnas, 2010, Skodlar et al., 2008), poor functioning (Haug et al., 2014, Raballo et al., 2016), and longer duration of untreated psychosis (Haug et al., 2015) in schizophrenia, and to failure to achieve symptomatic and functional recovery in patients with psychotic disorders (Svendsen, Merete, Møller, Nelson, Haug, & Melle, 2019).
Together, this body of research indicates that minimal self-disturbance is a trait vulnerability feature that has considerable specificity to schizophrenia spectrum disorders and is present in the prodromal phase of these disorders (Nelson et al., 2014, Nelson and Raballo, 2015, Parnas, 2011, Parnas, 2012, Parnas et al., 2002, Parnas and Henriksen, 2014, Sass and Parnas, 2003). Indeed, disturbed ‘self-experience’ is included in the schizophrenia criteria of the beta version of the International Classification of Diseases 11th revision (ICD-11) (Organisation, 2018).
In our view, schizophrenia research has suffered from a lack of integration across ‘levels’ of analysis, such as phenomenological, psychological, neurocognitive, neurobiological, genetic and social levels (Martin et al., 2014, Nelson et al., 2014a, Nelson et al., 2014b). We have argued that integrative models of vulnerability to schizophrenia spectrum disorders should be guided and constrained by the disorders’ core phenomenological features (Parnas & Zandersen, 2018), which can function as a central organising factor akin to Minkowski (1926) concept of le trouble générateur (generating disorder). Minimal self-disturbance is emerging as a strong candidate for this role. It is not clear at this stage how minimal self-disturbance relates to these different levels of analysis (see Sass, Borda, Madeira, Pienkos, and Nelson (2018) for a recent attempt at theoretical integration). Although there has been considerable recent empirical neuroscientific research into anomalies of bodily (e.g., Benson and Park, 2019, Sestito et al., 2017, Sestito et al., 2015), temporal (e.g., Giersch et al., 2016, Giersch and Mishara, 2017, Martin et al., 2018, Martin et al., 2014) or perceptual experience (e.g., Uhlhaas & Mishara, 2007) in the schizophrenia spectrum, this has tended not to extend to the broader construct of minimal self-disturbance which includes, but is not limited to, anomalous bodily, temporal or perceptual experience.
The theoretical models regarding neuro-correlates (neurocognitive, neurophysiological and neurobiological correlates) of minimal self-disturbance (Borda and Sass, 2015, Mishara et al., 2015, Nelson and Sass, 2017, Nelson et al., 2014a, Nelson et al., 2014b, Parnas et al., 1996, Sass and Borda, 2015) have not been sufficiently empirically examined to date. The four studies that have directly examined neurocognitive correlates of minimal self-disturbance have found no correlation or a weak correlation between the variables (Comparelli et al., 2016, Haug et al., 2012, Koren et al., 2017, Nordgaard et al., 2015). However, the neurocognitive variables examined in these studies were derived from traditional measures of general intelligence, psychomotor speed, working memory and executive function, which may lack specificity to the disturbances at play in minimal self-disturbance (Nelson and Sass, 2017, Nelson et al., 2014a, Nelson et al., 2014b). Indeed, two recent studies are consistent with the suggestion of more specific neuro-disturbances being of relevance to minimal disturbance. Sestito et al. (2015) found that facial reactions in response to negative emotional stimuli, recorded using electromyography, specifically and strongly correlated with minimal self-disturbance in schizophrenia spectrum patients. Martin et al. (2017) findings in schizophrenia indicated a relationship between compromised extraction of temporally predictive information assessed in experimental tasks and minimal self-disturbance. Given the complexity and foundational nature of the minimal self-disturbance construct it is likely that there are multiple rather than single neuro-mechanisms associated with this constellation of anomalous subjective phenomena (Martin et al., 2014).
Nelson et al. (Nelson and Sass, 2017, Nelson et al., 2014a, Nelson et al., 2014b) introduced a theoretical model proposing that the neuro-constructs of source monitoring deficits and aberrant salience may be of particular relevance to minimal self-disturbance in schizophrenia (see supplementary material video 1 for an animated diagram). Both of these constructs have been found to be prominent in schizophrenia spectrum disorders and related to psychosis risk (Gaweda et al., 2018, Gaweda et al., 2013, Waters et al., 2012). Source monitoring deficits refer to difficulties in making attributions about the origins of mental experiences, e.g., whether an experience was real or imagined, or whether its origin was internal (self-generated) or external (other-generated) (Crapse and Sommer, 2008, Stephan et al., 2009, Whitford et al., 2012). Aberrant salience refers to the reduced ability to suppress attention to irrelevant or familiar information or environmental stimuli (in other words, excessive attention to information that is irrelevant or highly familiar), leading to an unusual salience of stimuli (Kapur, 2003, Kapur et al., 2005).
There is strong face validity that the experiential disturbances that might arise from (and in turn consolidate (Sass et al., 2018)) these neuro-disturbances accord with many of the experiential alterations associated with minimal self-disturbance (Nelson and Sass, 2017, Nelson et al., 2014a, Nelson et al., 2014b, Sass et al., 2018). In brief, confusion regarding the origin of mental experiences associated with source monitoring deficits accord with a variety of aspects of minimal self-disturbance:
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diminished ‘ownership’ of mental content;
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confusion of self-other boundaries;
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hyper-reflexivity, i.e., heightened awareness of aspects of one’s experience that are normally tacit and implicit) (Poletti, Gebhardt, & Raballo, 2017).
Aberrant salience, due to the reduction in the constraining and directing role of context, also accords with various aspects of minimal self-disturbance:
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rigidity and perplexity in interaction with others/the world;
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disturbance of ‘common sense’ (intuitive social understanding);
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loosened ‘grip’ on the cognitive/perceptual world, i.e., the sharpness or stability with which meaning or perceptions emerge against a background context;
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frequent shifts in perspective that undermine the possibility of blocking out alternative perspectives (referred to as ‘perspectival abridgement’);
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weakened sense of the functional value (referred to as the ‘affordance value’) of objects;
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hyper-reflexivity (see Nelson et al., 2014a, Nelson et al., 2014b for full explication of this integrated model).
We recently reported the first empirical support for the source monitoring aspect of this model, i.e., an association between minimal self-disturbance and source monitoring deficits in early psychosis patients (Nelson et al., 2019). However, these data, presented in letter format, were only partial data from the study. The purpose of the current report is to present the full data of this first empirical test of the proposed neurophenomenological model. The focus here is on cross-sectional association between variables.
It is particularly valuable to research pathogenic models of psychotic disorders in the early stages of disorder because these stages may allow a clearer view of the mechanisms at play, before the effects of advanced illness stages cloud the clinical picture (Klosterkötter et al., 2001, Nelson et al., 2008, Parnas, 2000, Yung et al., 2004), as well as point towards possible preventative treatment targets. In this study, clinical measures, including the EASE, and neurocognitive and neurophysiological measures of source monitoring deficits and aberrant salience were administered in two patient groups (a first-episode psychosis [FEP] sample and an ultra-high risk [UHR] for psychosis sample), as well as a healthy control (HC) group. We hypothesised that:
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Minimal self-disturbance, source monitoring deficits and aberrant salience would show an increasing gradient of severity from HC to UHR to FEP individuals (HC < UHR < FEP). The expectation that minimal self-disturbance would show this differentiation between groups was based on the fact that schizophrenia spectrum cases are mostly highly represented in the FEP group.
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Minimal self-disturbance would be predicted by source monitoring deficits and aberrant salience in FEP and UHR individuals.
Section snippets
Setting
Patients were recruited from Orygen Youth Health Clinical Program (OYHCP), a tertiary public mental health service for young people aged between 15 and 25 years living in north-western Melbourne, Australia. UHR participants were recruited from the Personal Assessment and Crisis Evaluation (PACE) clinic, a specialist psychosis risk clinic within OYHCP, and FEP participants were recruited from the Early Psychosis Prevention and Intervention Centre (EPPIC), a specialist clinic for first-episode
Demographic and clinical characteristics
The samples consisted of 50 UHR, 39 FEP, and 34 HC participants. Demographic characteristics and clinical scale scores are presented in Table 1. The HC group was older (by a mean of 2 years) than the clinical groups. The UHR sample consisted of the following sub-groups: APS = 37 (74%), APS + Trait Vulnerability = 10 (20%), APS + BLIPS = 2 (4%), and Trait Vulnerability = 1 (2%). SCID diagnoses are presented in Table 2. At the time of assessment, 11 (22%) of the UHR group were taking
Discussion
Our first hypothesis was that minimal self-disturbance, source monitoring deficits and aberrant salience would show an increasing gradient of severity from HC participants to UHR patients to FEP patients (FEP < UHR < HC). There was partial support for this hypothesis. While minimal self-disturbance showed this pattern of severity, the neurocognitive and neurophysiological findings were less clear. One neurocognitive test of source monitoring deficits (the temporal binding task) showed the
Ethics statement
The study was approved by the Melbourne Health Human Research and Ethics Committee (HREC). Study participants provided full written and informed consent.
Acknowledgment
This study was supported by a Brain and Behavior Research Foundation (BBRF) Independent Investigator Award (23199) to BN.
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