Table 6.

Results and limitations.

Nr	Author/Year	Results	Limitations
1	Longden et al. (2020)	• Dissociative phenomena are significantly related to positive symptoms and disorganisation. • Associations with negative symptoms were of smaller magnitude or nonsignificant. • The effects considered in the review were observed across both clinical and nonclinical samples.	• Impact on the magnitude of effects due to patients being likely more symptomatic than nonclinical participants; • Fundamental differences in the constructs assessed by different measures; • The search strategy was limited to peer-reviewed English-language studies; • The same studies examined multiple psychotic experiences within the same sample
2	Farrelly et al. (2016)	No results available as this paper presents the protocol for a study to assess the feasibility and acceptability of a brief cognitive behavioural therapy intervention for individuals who have depersonalisation symptoms in the context of psychotic symptoms.
3	Hwu et al. (1981)	• The prevalence of the derealisation syndrome at initial evaluation is not different between the clinical (patients with schizophrenia) and the non-clinical groups.	not reported
4	Perona-Garcelan et al. (2008)	• The attention of subjects with hallucinations was more self-focussed than the nonclinical group; • A positive correlation (p<0.05) between self-focusing and dissociative experiences in subjects with hallucinations; • Depersonalisation - the only factor predicting auditory hallucinations (F[1,66] = 113.366, p =0.000); • Patients recovered from hallucinations had a significantly higher mean DES-II score than the nonclinical control group (T = 11.130, p = 0.009); • The subjects with psychotic disorder who had never had hallucinations, had a significantly higher score on the DES-II scale than the subjects in the nonclinical control group (T = 5.668, p =0.007). • Absorption - the patients recovered from hallucinations and those who had never had hallucinations had significantly higher scores than the nonclinical control group (T = 18.465, p = 0.012; T = 8.586, p = 0.007, respectively);	• Small sample size; • Limited in generalizability; • Only used single dissociative instruments.
5	Perona-Garcelan et al. (2012)	• Significant differences between the groups (p <.001) regarding depersonalisation, absorption and metacognitive variables • Both absorption and depersonalisation were positively associated with all Metacognition Questionnaire -30 subscales, and also with the total score (p <.01). • The variable with the most predictive power for hallucinations (scores on the PANSS) of all those used in this study was depersonalisation [F (1, 122) = 101.472, p <.001].	• Unable to establish any causal relationships between the variables studied; • Uncontrolled variable (schizophrenic patients were on antipsychotic medication while the rest of the subjects were not) that could affect the dependent variables; • Under reported symptoms; • Potential bias by the relationship between anxiety and depression and the dissociative variables; • Difficulties in understanding some of the items.
6	Wright et al. (2020)	• Metacognitive ability was a significant predictor of functional capacity, R2 = 0.23, F(1, 131)=38.98, p<.001; and functional outcome, R2 = 0.104, F(1, 133)=15.39, p<.001; and subjective recovery outcome in FEP R2 = 0.39, F(3, 57)=11.55, p<.001. • Metacognitive control was a significant predictor of functional capacity, R2 = 0.11, F(1, 130)=16.16, p<.001. • Metacognitive experience was a significant predictor of functional capacity, R2 = 0.101, F(1, 131)=14.6, p<.001; and functional outcome, R2 = 0.03, F(1, 132)=4.15, p=.04. • The FEP group demonstrated more accurate metacognitive experience (appraisal of experience), and higher scores on metacognitive monitoring compared to controls.	• The authors combined FEP and healthy control group in order to increase sample size and range of scores; • Individuals who typically engage in research studies tend to be higher-functioning, caution should be taken when applying these results to a lower functioning group.
7	Rosen et al. (2017)	• A highly positive correlation (p<0.001) between absorption and hallucinations, thought disorder; • 2 subtypes of absorption within the sample: Cluster One- Attenuated Ego Boundaries (AEB) - 55 participants both clinical and non-clinical (48%); Cluster Two - Stable Ego Boundaries (SEB) - 60 participants (52%). • A significant increase in PANSS positive, cognitive, excitement, depression factor scores in the AEB cluster compared to the SEB cluster; no significant differences between cluster groups in PANSS negative factor scores.	• Small sample size; • Results based largely on self report - limited generalizablity
8	Úbeda-Gómez et al. (2015)	• Distress caused by the voices correlated positively with self-focussed attention (private and public) (p< 0.001) and negatively with mindfulness (p<0.001); • A negative correlation was also found between mindfulness and self-focussed attention - private (p<0.05) and public (p<001); • Public self-focus was the only factor predicting distress caused by the voices [R2 = 0.25, F(1, 50)=17.66, p<.001;	•No causal relationships because of being a correlational study; •Not clearly isolated differences among groups with regard to the variables involved.
9	Humpston et al. (2016)	• Detachment and absorption predicted levels of delusional ideation and anomalous perceptual experiences; • Compartmentalisation did not predict psychosis-like experience; • Detachment and absorption are largely distinct from psychosis-like experience and do not reflect similar constructs.	•Not possible to determine the direction of causality; •The results may not always fully translate to other cultural settings.
10	Lynch et al. (2018)	Participants reported that through art therapy, they were able to build up relationships, connect with others, sustain participation and therapeutic engagement and experience therapeutic change.	•The service users were not involved in the design or execution of the study; •Not all participants brought artwork to discuss during the interview.
11	Bacon & Kenedy (2014)	• A model of the Theory of Structural Dissociation of the Personality (TSDP) suggests that the difference between psychosis and dissociation is circumstantial, dependent on the structural dissociation and mental level of an individual’s personality (or parts thereof) at that time. It validates suggestions of a continuum-based approach to psychosis and dissociation as traumatic reactions.	•Difficult to disentangle the authors own beliefs from the experiences and understandings of the participants; •Factors such as participant nationality, profession and recruitment organisation may have influenced the findings.
12	Ross & Keyes (2009)	The authors predicted that the dissociative subtype of schizophrenia affects in the range of 25–40% of individuals meeting DSMIV-TR diagnostic criteria for schizophrenia. They diagnosed dissociative schizophrenia in 22% of the 50 cases interviewed. The percentage of cases assigned to the proposed dissociative subtype was within the range of the research-based prediction.	•The interviews were conducted by foreigners using translators; •Vague histories given by the participants; •Potential memory problems due to institutionalisation, ECT and medications; •Limited size of sample; •The lack of knowledge of dissociation making questions unclear to the participants.
13	Lysaker et al. (2020)	• No statistics reported; • Deficits in metacognition commonly occur in schizophrenia and are related to basic neurobiological indices of brain functioning; • The capacity for metacognition in schizophrenia is positively related to a broad range of aspects of psychological and social functioning when measured concurrently and prospectively; • Metacognitive Reflection and Insight Therapy (MERIT) has the potential to treat fragmentation and promote recovery.	•Difficulty measuring the extent of metacognitive deficit; •Lack of long term, longitudinal studies.
14	Lysaker et al. (2018)	•Review of major theories of alterations in self- experience in schizophrenia; • Results: The authors argue that research on metacognition suggests that reduction in metacognitive function may partially explain the occurrence of these difficulties and also explain how their resolution contributes to recovery.
15	Kumar et al. (2018)	•50% reduction of PSYRATS score on the items related to the beliefs about origins of voices, intensity of distress, interference with life and controllability; •May be effective in patients who are not receiving antipsychotic treatment.	•Limited generalizability of the findings; •No discussion about the impact of the disappearance of the psychotic experiences; •No standard measure to assess the subjective rating of patient about recovery; •No tool for assessment of patient’s metacognitive capacities.
16	Perivolioitis et al. (2009)	• Psychological intervention can be adapted to successfully treat patients with schizophrenia who lack insight; • The cognitive formulation of negative symptoms provides a useful roadmap; • The importance of experiential learning in driving both behaviour change and belief modification.	•Under reporting symptoms and guarded
17	Pec et al. (2020)	The metacognitive approach might provide operational definitions for psychoanalytic concepts in schizophrenia related to self-disturbance and the emotional, cognitive, and social disruptions associated with psychoanalytic understanding of fragmentation.
18	Bob & Mashour (2011)	• Significant overlaps between the symptomatology and experimental data regarding dissociative processes and schizophrenia. • Although direct evidence is lacking, the investigation of dissociative processes may be beneficial for understanding certain types of schizophrenia.
19	Ross (2006)	It proposes a dissociative subtype of schizophrenia.