Sensory thresholds and the sense of bodily identity in schizophrenia

Aim of the study The aim of the study was to investigate: 1) whether schizophrenia is associated with disturbances in bodily identity (BI) and in sensation thresholds (STs) assessed by a questionnaire and experimental methods (pain and proprioception thresholds); 2) whether disturbances in STs are related to BI in the schizophrenia group. Subject or material and methods Fifty-four outpatients with schizophrenia in remission and 54 controls completed: Bodily Identity Scale, Heightened Thresholds Scale, and Lowered Thresholds Scale. Their pain and proprioception thresholds were estimated using the TempTest Apparatus and the Discrimination Weights Test, respectively. Results Compared to the control group, patients with schizophrenia: reported more disturbances in BI and in the STs examined by questionnaire, displayed increased proprioception, but a lower pain threshold. In the schizophrenia group disturbances in BI were only associated with distortions in STs examined by questionnaires. Discussion Disturbances in stimulus processing in the experimental setting did not explain disruptions in BI in schizophrenia, which may be due to the study's methodology and the weak (pain threshold) or moderate (proprioception threshold) manifestation of STs disturbances in the experimental setting in the clinical group. Conclusions In schizophrenia remission no coherent pattern of sensitivity to experimental stimuli is observed. The increased sensitivity to experimental pain in patients in remission is consistent with the results of previous studies, and undermines the popular thesis of pain indifference in schizophrenia. Patients with schizophrenia struggle throughout their lives with disturbances of bodily identity and states of both over- and under-sensitivity to environmental stimuli.