**2.1. Some psychotic-like experiences could be less worrisome than others, but might some also be beneficial?**

[30, 31]. Therefore, two corresponding items were dropped from the analyses in a subsequent study [29]. This time, PLE clustered into four classes, i.e. BE, PI, PA, and grandiosity while all subtypes were associated with one or more indicators of disadvantage. The authors speculated that PI and BE might lead to more evident symptoms than PA and GR, as they are more invasive experiences and more disruptive of the self-structure. Importantly, the studies showed that all forms of PLE were associated with disadvantage, once items specifically related to paranormal beliefs (but not grandiosity) were removed. At the same time, however, they indicated that PLE might be maladaptive in different ways and it was speculated that

Subtypes of Psychotic-Like Experiences and Their Significance for Mental Health

http://dx.doi.org/10.5772/intechopen.78691

7

they may confer varying levels of risk for psychosis and other mental disorders [29].

The latter studies inspired a more extensive investigation of the specific relationships between different subtypes of PLE and "co-morbid" subclinical symptoms in healthy adults [28]. The study aimed at gaining first information about possible symptom-level mechanisms implicated in the emergence of mental disorders featuring psychotic symptoms and a meaningful categorization of PLE. Importantly, the researchers not only included experiences that are relevant regarding the specific extended psychosis phenotype (i.e., including positive-, negative-, and disorganized-like symptoms) but also those that are associated with the more recent notion of a transdiagnostic extended psychosis phenotype (i.e., also including affective symptoms). PLE were operationalized using the positive scales of the Schizotypal Personality Questionnaire (SPQ), (see [49]). Further extending the description of PLE, a novel questionnaire was included whose items were not derived from clinical symptom presentations (the revised Questionnaire for Assessing the Phenomenology of Exceptional Experiences (PAGE-R), see [50]) and that had just recently been introduced into psychosis research [44]. Whereas most subclinical symptoms were correlated, the researchers found unique associations between certain PLE and subclinical symptoms that were consistent across the numerous applied scales when co-occurring PLE were controlled for: paranoia-like experiences (suspiciousness) were uniquely associated with various scales measuring negative-like experiences. In contrast, different hallucination-like experiences (including dissociation) exclusively predicted different anxiety-related experiences while ideas of reference appeared to be specifically implicated with affective symptoms (anxiety and depression). Importantly, numerous negative associations between PLE and other subclinical difficulties were detected, namely between ideas of reference and physical anhedonia, magical thinking and constricted affect, PAGE-R odd beliefs (e.g., seeing meaning in coincidences) and depression, emotional instability, as well as unspecific symptoms (e.g., difficulties falling asleep). Notably, unlike suspiciousness and ideas of reference, magical thinking and PAGE-R odd beliefs did not positively predict any subclinical symptoms. While these results pointed to possible symptom-level interactions implicated in the development of psychosis spectrum disorders [37, 38], they also contributed to an empirically founded and much-needed categorization of PLE [30, 39]. Furthermore, the findings suggested that negative associations between PLE and other subclinical symptoms might be more extensive than previously thought and indicated that some delusion-like PLE *per se* might be associated with less psychological difficulties while being indicative of increased psychological burden at the same time (as indicated by their positive correlations with diverse psychological difficulties). Interestingly, there are complementary findings suggesting that some PLE might not only go along with less co-occurring subclinical symptoms but also with well-being. In a sample of university students, it was found that ideas of reference positively predicted subjective well-being, (e.g., standard of living, community-connectedness), when

Some of the earliest evidence raising the question if different PLE might be variably associated with disadvantage and mental health comes from research using the Wisconsin Schizotypy Scales [40–42]. It was found across several studies that PLE relating to magical thinking (MT) (and perceptual aberrations) were negatively correlated with physical anhedonia, but not other scales measuring negative-like symptoms [28, 41, 43, 44]. Notably, the negative associations were detected in samples of college students and healthy adults while the correlation was close to zero in outpatient clinic clients and schizophrenics [40, 43]. However, analyses indicated a true incompatibility of magical ideation and physical anhedonia rather than sampling effects as a cause for this pattern [43]. It was suggested that people scoring high on both magical ideation and physical anhedonia are more likely to become hospitalized, which might cancel out the otherwise negative correlation in these populations. Whereas these findings still remain to be explained, it has been speculated that magical ideation might reduce physical anhedonia by conveying meaning to (sensory) experiences or that both are linked through a third factor, e.g., extraversion and emotional stability [28, 45]. However, room for interpretation is limited, as most of the aforementioned scales for PLE may contain several different constructs rather than one. For example, the Magical Ideation Scale (MIS), (see [41]) includes paranormal beliefs, superstitious beliefs, ideas of reference, and suspiciousparanoid thoughts [46]. Hence, it is not clear which of the contained constructs are ultimately responsible for the observed associations. Nonetheless, the results indicated that it might be important to differentiate between subtypes of PLE, as they might be variably associated with other psychological (risk) factors.

Less ambiguous evidence for differences in the psychopathological significance of PLE comes from more recent research using the Community Assessment of Psychic Experiences Questionnaire (CAPE), (see [47]). The CAPE was constructed to investigate the extended psychosis phenotype [15] and has become one of the most frequently used self-report instruments for PLE [34]. A few studies have investigated which categories underlie PLE in the CAPE and how they are related to factors indicating risk for transition to psychotic disorder, i.e. distress, depression, and impairment [48]. Using exploratory factor analyses, one study identified bizarre experiences (BE), persecutory ideas (PI), and magical thinking (MT) to underlie the CAPE positive dimension in a sample of non-psychotic help-seekers [31]. Interestingly, only BE and PI were found to be associated with distress, depression, and poor functioning while MT was not. Notably, reminiscent of the aforementioned studies implementing the MIS, the researchers also found that MT was not correlated with anhedonic depression, unless accompanied by distress. Further, MT even turned out to be a negative predictor of anhedonic depression when adjusted for BE and PI. The apparent lack of associations of MT with any maladaptive feature such as depression and poor functioning lead the researchers to suggest that MT might be benign. Similarly, in a community sample of high school students, four types of PLE were found, namely BE, perceptual abnormalities (PA), PI, and MT [30]. Again, only BE, PI, and PA but not MT were strongly associated with distress, depression, and poor functioning. It was thought that the lacking association of MT with indicators of disadvantage could be explained with the finding that two items referring to paranormal beliefs were more closely associated with age and cultural background than psychopathology [30, 31]. Therefore, two corresponding items were dropped from the analyses in a subsequent study [29]. This time, PLE clustered into four classes, i.e. BE, PI, PA, and grandiosity while all subtypes were associated with one or more indicators of disadvantage. The authors speculated that PI and BE might lead to more evident symptoms than PA and GR, as they are more invasive experiences and more disruptive of the self-structure. Importantly, the studies showed that all forms of PLE were associated with disadvantage, once items specifically related to paranormal beliefs (but not grandiosity) were removed. At the same time, however, they indicated that PLE might be maladaptive in different ways and it was speculated that they may confer varying levels of risk for psychosis and other mental disorders [29].

**2.1. Some psychotic-like experiences could be less worrisome than others, but might** 

Some of the earliest evidence raising the question if different PLE might be variably associated with disadvantage and mental health comes from research using the Wisconsin Schizotypy Scales [40–42]. It was found across several studies that PLE relating to magical thinking (MT) (and perceptual aberrations) were negatively correlated with physical anhedonia, but not other scales measuring negative-like symptoms [28, 41, 43, 44]. Notably, the negative associations were detected in samples of college students and healthy adults while the correlation was close to zero in outpatient clinic clients and schizophrenics [40, 43]. However, analyses indicated a true incompatibility of magical ideation and physical anhedonia rather than sampling effects as a cause for this pattern [43]. It was suggested that people scoring high on both magical ideation and physical anhedonia are more likely to become hospitalized, which might cancel out the otherwise negative correlation in these populations. Whereas these findings still remain to be explained, it has been speculated that magical ideation might reduce physical anhedonia by conveying meaning to (sensory) experiences or that both are linked through a third factor, e.g., extraversion and emotional stability [28, 45]. However, room for interpretation is limited, as most of the aforementioned scales for PLE may contain several different constructs rather than one. For example, the Magical Ideation Scale (MIS), (see [41]) includes paranormal beliefs, superstitious beliefs, ideas of reference, and suspiciousparanoid thoughts [46]. Hence, it is not clear which of the contained constructs are ultimately responsible for the observed associations. Nonetheless, the results indicated that it might be important to differentiate between subtypes of PLE, as they might be variably associated with

Less ambiguous evidence for differences in the psychopathological significance of PLE comes from more recent research using the Community Assessment of Psychic Experiences Questionnaire (CAPE), (see [47]). The CAPE was constructed to investigate the extended psychosis phenotype [15] and has become one of the most frequently used self-report instruments for PLE [34]. A few studies have investigated which categories underlie PLE in the CAPE and how they are related to factors indicating risk for transition to psychotic disorder, i.e. distress, depression, and impairment [48]. Using exploratory factor analyses, one study identified bizarre experiences (BE), persecutory ideas (PI), and magical thinking (MT) to underlie the CAPE positive dimension in a sample of non-psychotic help-seekers [31]. Interestingly, only BE and PI were found to be associated with distress, depression, and poor functioning while MT was not. Notably, reminiscent of the aforementioned studies implementing the MIS, the researchers also found that MT was not correlated with anhedonic depression, unless accompanied by distress. Further, MT even turned out to be a negative predictor of anhedonic depression when adjusted for BE and PI. The apparent lack of associations of MT with any maladaptive feature such as depression and poor functioning lead the researchers to suggest that MT might be benign. Similarly, in a community sample of high school students, four types of PLE were found, namely BE, perceptual abnormalities (PA), PI, and MT [30]. Again, only BE, PI, and PA but not MT were strongly associated with distress, depression, and poor functioning. It was thought that the lacking association of MT with indicators of disadvantage could be explained with the finding that two items referring to paranormal beliefs were more closely associated with age and cultural background than psychopathology

**some also be beneficial?**

6 Psychosis - Biopsychosocial and Relational Perspectives

other psychological (risk) factors.

The latter studies inspired a more extensive investigation of the specific relationships between different subtypes of PLE and "co-morbid" subclinical symptoms in healthy adults [28]. The study aimed at gaining first information about possible symptom-level mechanisms implicated in the emergence of mental disorders featuring psychotic symptoms and a meaningful categorization of PLE. Importantly, the researchers not only included experiences that are relevant regarding the specific extended psychosis phenotype (i.e., including positive-, negative-, and disorganized-like symptoms) but also those that are associated with the more recent notion of a transdiagnostic extended psychosis phenotype (i.e., also including affective symptoms). PLE were operationalized using the positive scales of the Schizotypal Personality Questionnaire (SPQ), (see [49]). Further extending the description of PLE, a novel questionnaire was included whose items were not derived from clinical symptom presentations (the revised Questionnaire for Assessing the Phenomenology of Exceptional Experiences (PAGE-R), see [50]) and that had just recently been introduced into psychosis research [44]. Whereas most subclinical symptoms were correlated, the researchers found unique associations between certain PLE and subclinical symptoms that were consistent across the numerous applied scales when co-occurring PLE were controlled for: paranoia-like experiences (suspiciousness) were uniquely associated with various scales measuring negative-like experiences. In contrast, different hallucination-like experiences (including dissociation) exclusively predicted different anxiety-related experiences while ideas of reference appeared to be specifically implicated with affective symptoms (anxiety and depression). Importantly, numerous negative associations between PLE and other subclinical difficulties were detected, namely between ideas of reference and physical anhedonia, magical thinking and constricted affect, PAGE-R odd beliefs (e.g., seeing meaning in coincidences) and depression, emotional instability, as well as unspecific symptoms (e.g., difficulties falling asleep). Notably, unlike suspiciousness and ideas of reference, magical thinking and PAGE-R odd beliefs did not positively predict any subclinical symptoms. While these results pointed to possible symptom-level interactions implicated in the development of psychosis spectrum disorders [37, 38], they also contributed to an empirically founded and much-needed categorization of PLE [30, 39]. Furthermore, the findings suggested that negative associations between PLE and other subclinical symptoms might be more extensive than previously thought and indicated that some delusion-like PLE *per se* might be associated with less psychological difficulties while being indicative of increased psychological burden at the same time (as indicated by their positive correlations with diverse psychological difficulties). Interestingly, there are complementary findings suggesting that some PLE might not only go along with less co-occurring subclinical symptoms but also with well-being. In a sample of university students, it was found that ideas of reference positively predicted subjective well-being, (e.g., standard of living, community-connectedness), when adjusted for co-occurring PLE, negative- and disorganized-like symptoms [51]. Notably, this finding was in line with suggestions that ideas of reference (in contrast with paranoia) must not necessarily be burdensome [52, 53].

preventing any causal conclusions to be drawn. Further, the samples were not representative of the non-clinical part of the general population (e.g., consisting of high school students), which puts the representativeness of the results into question. Further, it is not clear if e.g., odd beliefs are similarly associated with indicators of well-being and disadvantage across the psychosis continuum and across other instruments assessing PLE. It might well be that the tendency to have odd beliefs might worsen outcomes in some cases by acting as an accelerant among other PLE. Nonetheless, the reported results might serve as starting points for the creation of theoretical models and longitudinal investigations into the interplay of subclinical symptoms leading to the exacerbation of subclinical symptoms or the maintenance of mental

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9

Self-report instruments for psychotic-like experiences (PLE) are a central source of information in epidemiological research on subclinical psychosis. However, it is mostly not regarded that these instruments are tied to certain conceptualizations of (subclinical) psychosis and originally served a specific purpose [24, 25, 34]. Notably, many instruments used to assess PLE stem from schizotypy research and are fundamentally influenced by the underlying schizotypy model and the assumed link between schizotypal personality features and schizophrenia. For example, one of the earliest and most frequently used schizotypy scales is the Magical Ideation Scale (MIS, see [41]) [34]. It bases on Meehl's [11] quasi-dimensional schizotypy model and as a screening tool for psychosis proneness (and vulnerability to schizophrenia in particular) its scope is restricted to illness and schizophrenia risk [25]. Accordingly, the MIS conceptualizes "psychotic-like symptoms" as attenuated or milder forms of Schneiderian first-rank symptoms of schizophrenia that manifest in the acceptance of unconventional forms of causality. Hence, the items in the MIS might have a distinct bias toward schizophreniarelated PLE. Furthermore, the selection of items might not be reflective of different forms of PLE in the general population, as items with extremely high and low difficulties were chosen to attain normality of the scale score. In comparison, the popular Schizotypal Personality Questionnaire (SPQ, see [49]) was constructed to screen for schizotypal personality *disorder* according to DSM-III-R criteria and not to assess schizotypal personality organization [25]. Hence, its categorization of PLE into paranormal beliefs/magical thinking, ideas of reference, suspiciousness, and unusual perceptual experiences is entirely derived from a theoretical diagnostic profile. Notably, item-level factor analyses have repeatedly produced incongruent categorizations of the experiences [71]. One of the most widely used self-report instrument to assess PLE not founded on schizotypy research is the Community Assessment of Psychic Experiences Questionnaire (CAPE, see [47]). The CAPE was created against the theoretical background of the extended subclinical psychosis phenotype [15] and is an attractive tool for clinical and research use, as it is comprehensive and measures not only the frequency of PLE but also distress associated with them [48]. In contrast to questionnaires assessing attenuated versions of clinical symptoms, the CAPE inquires symptoms seen in patients with psychotic disorders (albeit toned down by adding "as if" to the questions). Hence, existing instruments assessing PLE may differ regarding the constructs they cover, the qualitative expression of

**2.2. The heterogeneous conceptualization and assessment of psychotic-like** 

health, respectively [28].

**experiences**

Odd beliefs as measured by the PAGE-R were prominently represented in the detected negative associations. Importantly, odd beliefs refer not to beliefs in a strict sense, but to experiences characterized by "seeing" patterns in noise (e.g., meaningful linking of separate events, correctly anticipating future events). Importantly, this sets odd beliefs apart from scales assessing e.g., magical thinking that often contain paranormal beliefs rather than experiences, which might be less relevant for the study of subclinical psychosis [54]. Further, in contrast to most studied forms of delusion-like experiences (e.g., suspiciousness), odd beliefs in healthy individuals were particularly enriching and positively-valenced experiences. Nonetheless, odd beliefs are conceptually similar to other delusion-like experiences and may be associated with indicators of psychosis proneness, such as biases in probabilistic reasoning and a tendency to jump to conclusions [55, 56], alterations in attributional styles [57, 58], differences in theory of mind [59], and magical ideation [60]. Importantly, experiences similar to odd beliefs have been suggested to reduce distress in perceptually ambiguous or stressful situations [61, 62] and to facilitate (perceived) control as well as to confer confidence and agency under lack of control [63]. Before this background, it was speculated that odd beliefs in healthy individuals might represent a psychologically stabilizing cognitive response to burdensome experiences [28]. Hence, despite their delusion-like quality, odd beliefs might paradoxically exert a positive effect on psychological well-being. Intriguingly, a new study investigating specificities between PLE and forms of childhood trauma found for the first time that odd beliefs in healthy adults were associated with stronger self-concept of own competences (SC), when adverse childhood experiences were held constant [64]. In contrast, paranoid-like experiences remained negatively associated with SC once adjusted for childhood adversities. SC is the fourth dimension of locus of control according to Rotter's social learning theory [65, 66] and refers to the self-perceived capability to act in new, difficult or ambiguous situations [67]. Notably, addressing SC might also strengthen self-esteem, which has been identified by individuals with schizophrenia to be the most important treatment target [68]. Moreover, strengthening SC in therapy might help to alleviate psychotic symptoms SC [66]. Due to their positive association with SC the question was raised if odd beliefs might contribute to resilience toward mental illness, despite conferring an inaccurate perception of the world [64]. Further, as an individual's inability to give meaning to an adverse experience is important in determining its long-term effect [69], the tendency to have positive delusion-like experiences might perhaps be exploited for therapeutic purposes.

The presented findings suggest that despite their tendency to co-occur, PLE may be variously implicated in mental illness and mental health. These results are in line with earlier suggestions that a co-occurrence of characteristics seen in pathological and non-pathological conditions must not necessarily mean that they are indicators of psychopathology [70]. More specifically, some characteristics could simply be by-products of the psychosis dimension but not be clinically relevant *per se*. However, it is cautioned to jump to premature conclusions and these symptom-level insights require further investigation, as there are several limitations to be considered. For example, all studies applied cross-sectional study designs, preventing any causal conclusions to be drawn. Further, the samples were not representative of the non-clinical part of the general population (e.g., consisting of high school students), which puts the representativeness of the results into question. Further, it is not clear if e.g., odd beliefs are similarly associated with indicators of well-being and disadvantage across the psychosis continuum and across other instruments assessing PLE. It might well be that the tendency to have odd beliefs might worsen outcomes in some cases by acting as an accelerant among other PLE. Nonetheless, the reported results might serve as starting points for the creation of theoretical models and longitudinal investigations into the interplay of subclinical symptoms leading to the exacerbation of subclinical symptoms or the maintenance of mental health, respectively [28].
