Schizophrenia is characterized by experiencing false perceptions and beliefs (1). Current phenomenological literature emphasizes the concept of schizophrenia as the self (ipseity) disturbance (1). The term ipseity is understood as the minimal, subjective feeling of self and decides about the perception of reality as one's own experience (2). Ipseity Disturbance Model (IDM) proposed by Sass and Parnas (3) explains schizophrenic symptoms regarding three phenomena: hyper-reflexivity (forced self-orientation leading to aberrant salience), diminished self-presence is defined as the loss of subjectivity in the feeling of awareness, and disturbed grip or hold leads to perceptual aberrancies (3, 4). IDM finds reflection in clinical data. The use of Examination of Anomalous Self-Experience (EASE), the standardized questionnaire for patients with a schizophrenia diagnosis, provides a clear dissection of schizophrenia symptomatology from the bipolar psychotic state (4). Significant disturbance of ipseity may also be present in other schizophrenia spectrum disorders and at-risk mental state (5).

Ipseity disturbance has been therefore suggested as the basic psychotic state, which leads to secondary phenomena, such as positive symptoms and loss of body awareness (6). The subjective feelings of the body change during schizophrenia (disembodiment), leading to misattribution of inner states, normal feelings, uncoupling with bodily representations, which may lead to extraordinary, delusional explanations (7).

Stanghellini, in the literature review (2009) (8), emphasizes disembodiment as the core feature of schizophrenia and subdivides it into three domains: disembodied of the self, disembodiment of self-object relations, and disembodiment of intersubjectivity. In the first domain, the patient due to disembodied view of the organism reveals the conviction about the deaminated body (8). The primary problem of disrupted self-awareness impacts daily activities and the relation to the treatment schedule (9). Lack of integrated representation of self also generates further metacognitions, such as poorer levels of self-reflectivity (10). The second domain described by Stanghellini fasters changed the meaning of usual objects for the patients with schizophrenia, who loses clear representation of the external world. The third one, intersubjectivity, refers to the combination of somato-psychic and auto-psychic depersonalization, leading to social isolation, observed as schizophrenic autism (8). Symptoms of schizophrenia may be a direct consequence of disembodiment due to problems in the recognition of familiar patterns in perception (11).

Perceptual and thinking aberrancies may have roots in disembodiment affecting the structure of a patient's language (disembodied language). As reported in previous studies, linguistic abnormalities are a core feature of schizophrenia (12), may serve as a marker, especially in the early stages of the disease (13), and predict conversion from at-risk mental state to schizophrenia. The potential role of language disembodiment in psychotic phenomenology derives from linking the language disturbances with the concept of ipseity.

The concept of language embodiment is based on a bi-directional hypothesis and connects somatic representations of sensory or motor perceptions with language semantics (14, 15). This mechanism activates bodily experiences in the inner, solipsistic simulation of the reality with the use of linguistics (Perceptual Symbol System, PSS) (16). PSS explains the role of language information in priming the motoric response, such as in the study by Zwaan et al. (17), where participants presented with a sentence (containing spatial modalities) tend subsequently to respond faster to matching visual stimuli. Hence, the hypothesis about the occurrence of language-induced simulation precedes and enables proper reaction. Similar results were obtained after the presentation with the shape and motion of an object (18).

There is a lack of studies on language embodiment assessment in schizophrenia. The available approach explored mind-body connection in the communicational aspect in patients with schizophrenia, who tend to exhibit difficulties in understanding emotional body language; deficits corresponded with the severity of the disease's symptoms (19). Inner and subjective processing of language not only appears as a possible aspect of general linguistic disturbances in psychosis but may also lead to particular secondary phenomena, such as auditory verbal hallucinations (AVHs; misattribution of inner speech) (20). From this point of view, the assessment of disembodied language seems to be an essential paradigm in further understanding schizophrenia psychopathology.

The study presents the preliminary analysis of disembodied language assessment in relation to psychotic symptoms, based on widely used clinical tools. To assess language disembodiment, we used authors' test (ZVT). We aimed to construct an easy-applicable clinical tool to assess language disembodiment. In the manuscript, we focused on the link between disturbed spatial understanding of language and clinical characteristics of early-onset schizophrenia spectrum disorders.

Early-onset psychosis population differed significantly from the healthy control group in the outcomes of ZVT and TLCS. The performance of ZVT did not correspond with general improvement after standard pharmacotherapy and was associated with the presence of auditory hallucinations. In relation to experienced symptoms, ZVT occurred to be connected with aberrant perception, whereas TLCS deficits corresponded with delusional thought content.

The language of patients with schizophrenia has been studied so far that thoroughly include semantic and syntax aspect, such as automatic language analysis (31). Recent research indicates the link between language disturbance and negative symptoms (32). In our study, obtained data suggest coincidence regarding hallucinations and delusional ideation. Beyond reliable data on linguistics, using phenomenology-derived concepts, such as embodiment, may improve schizophrenia diagnosis in an early age. What has been shown in our study, disembodiment appears to be a parallel dimension of disturbed language, linked with auditory hallucinations.

Here, we understood the language disembodiment as a part of general disembodiment due to self-disturbances (SD) (3). Recent data suggest SD as a trait phenomenon, remaining a constant domain of psychopathology (2) and a potential marker of schizophrenia spectrum (33). Empirical studies using EASE revealed a significant coincidence of self-disorder with typical formal thought aberrancies and imagination anomalies (34), which suggests the crucial role of the self in language processing. An embodied approach to language defines concepts as having the same structure as perceptions, such as the color, shape, movement, and emotional value (35). In the study, we have used spatial properties.

Observed differences in word placing may also be explained alternatively than as the part of the disordered self. A major confounding factor is the use of word semantics during the task. Presented deficits may not reflect spatial (somatic) representation of words, but aberrant semantic networks are evidenced for patients with psychosis (36) and semantic priming effect (37). This effect enables faster decision-making due to presentation with context information, hence in our study, preceding words could induce choosing the other one as the next in the procedure of placing. Word placing schedule may be also affected by deficits in working memory and decision-making typically present in schizophrenia. As it was shown in word-fluency tests, deficits in working memory affect the outcome of language abilities (38).

Zabór Verbal Task outcome is shown to be connected with the presence of visual and auditory hallucinations, initial thought, language and communication deficits, and initial rate of positive symptoms. The performance of ZVT did not correspond with general improvement after standard pharmacotherapy. From the results we obtained, embodied language might potentially serve as a neuropsychological biomarker of psychosis, independent from the state of exacerbation/remission, but present and characteristic of the disease. This direction requires further studies.

Results of this preliminary study indicate disembodied language as a clinically valuable parameter in the general psychopathology of schizophrenia. Further studies need to find an answer about the relation of language disembodiment with other thought disorders. The open question is the primacy of disembodiment before psychotic symptoms or secondary character of disembodiment. Following this approach, typical for schizophrenic patients' delusionary feelings of external influence, such as thought insertion or thought withdrawal, may be the direct consequence of disturbed ipseity (2) and language disembodiment (see Figure 2). Such an approach underlines the role of subjective experience in treatment. Current perception of remission in schizophrenia regards more often explicit and visible positive symptoms and does not provide better self-integrity of patients (6); as has been shown in our study, standard neuroleptic treatment did not show benefits in the spatial understanding of language, hence future therapeutic interventions for people at risk to develop schizophrenia may benefit from self-directed psychotherapy (39).

The study is not free from limitations. We did not assess the TLCS objectively, by recording the patient's utterance before analysis due to ethical concerns. Instead of this, the utterance was assessed directly after the examination, which is prone to subjectivity. The second limitation is the number of participants included. Several scales for clinical description (such as EASE) were omitted in the investigation of ZVT correlation with other symptomatology. Hence the preliminary character of the outcomes is the purpose for further studies the wider population.

The original contributions presented in the study are included in the article/Supplementary Material, further inquiries can be directed to the corresponding author.

The study was designed and conducted by the appointment of the Local Bioethics Commission at Poznan University of Medical Sciences (1066/19). Written informed consent to participate in this study was provided by the participants' legal guardian/next of kin.

PZ, MS, and JP: methodology and manuscript preparation. PZ: recruitment and clinical evaluation. MS: computations. All authors contributed to the article and approved the submitted version.

The research was financed from the large research grant from statutory funding for young researchers–doctoral students for 2021 and Department of Psychiatric Genetics statute sources: 502-20-22196440.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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