Interpersonal Functioning of the People Wwith Schizophrenia: Associations With Theory of Mind and Working Memory

<Introduction>

     It is necessary to receive an information such as a surrounding and an expression of the speaker, intention, feelings appropriately and to response in accord with the context of the conversation in order to interchange with others smoothly. Receiving an information in the interpersonal scene is affected by Theory of Mind (ToM) which is an important cognitive function to understand and inference of mental states (beliefs, thoughts, and intention) of self and others (Pos et al, 2015).If we obtain it, we able to explain and predict behavior of others. Understanding of other person’s mental states requires explicit representation of wrongness of one’s own mental states (Wimmer & Perner, 1983). In addition, person needs to memorize it temporarily.

     Brüne (2003) suggested that ToM is affected by Working memory which is a system to maintain an information temporarily and handle it. People have occasion to keep particular pieces of critical information briefly in mind, storing them until the opportunity to use them arrives. In the communication scene, not only do we need to keep certain bits of information accessible in mind, but also we need to perform cognitive processing. These short-term mental storage and manipulation operations are collectively called Working memory.

     The person with schizophrenia tend to misunderstand meaning of the behavior of others, and have obstacle to answer that others expect correctly. By such these characteristics, they have various difficulty for interpersonal interchange that is related to every scene of daily life. Skantze et al (1992) reported their Quality of Life about relationships with family, friends, and person of the opposite sex decreased. The goal of psychiatric treatment is not only to control symptoms but also to increase QOL and to support their lives which they want to. In order to self-actualization of them, we need to reveal features of their interpersonal functioning and to improve it.

<Objective>

The objective of this study is to investigate associations with Theory of Mind and Working memory in the interpersonal functioning of the person with schizophrenia.

 

<Methods>

Subjects:

A total of 155 patients had a DSM-5 or ICD-10 diagnosis of schizophrenia. There are 79 male and 76 female. Exclusion criteria included dementia and current or past central nervous system disease or history of head injury, current substance abuse, a history of substance dependence or impaired general cognitive functioning.

Materials:

Interpersonal functioning assessment

Interpersonal functioning was assessed with Life Assessment Scale for the Mentally Ill (LASMI). It is able evaluate the obstacle in the social life of the mental patient objectively and comprehensively. In this study, subjects were assessed with subscale “Interpersonal relations” was constructed in ‘Conversation’ (7domeins), ‘Group activity (3domeins)’, and ‘Relationship (4domeins)’.

Theory of Mind

Subjects were given one first-order and one second-order false belief tests of Theory of Mind. Tasks were read aloud and cards drawn the picture on were displayed in front of subjects. Memory control questions were asked throughout each task to check that subjects could remember key facts to check that subjects could remember key facts about the story. The ‘test question’ in each task was the measure of representational understanding.

The first-order false belief task (FB1) was “The Ann and Sally story” in which the subject must recognize that a story character has a false belief about the location of an object. The second-order false belief task (FB2) was “Ice-cream van’s story”, where the subject must attribute a story character’s false belief about another character’s belief.

Working memory

To assess Working memory, Trail Making Test B was used. TMT-B is a timed test that requires to quickly combine encircled numbers and characters in ascending order.

 

Analysis:

The Mann-Whitney U test was used to detect difference between correct and incorrect answer in false belief tests in relation to LASMI-I and TMT-B. In order to investigate the relationship between LASMI-I and TMT-B, Spearman’s correlation test was used. We used the Statistical Package for Social Sciences (SPSS) version22, at the 95% confidence level.

Ethical considerations:

This study was approved by port facilities and University of Tsukuba Faculty of Medicine, Ethics Committee. Written informed consent was consent was obtained from participants, before the initiation of any research procedures.

<Results>

Schizophrenic subjects were 53 inpatient and 102 outpatients (79 male and 76 female). The mean age was 45.98 years (SD=12.76), the mean onset age was 25.64 years (SD=8.53), and the mean disease duration was 19.66 years (SD=12.23). All subjects were taking neuroleptics and the mean chlorpromazine-equivalent dose was 711.75mg (SD=661.97).

107 subjects gave correct answers on FB1, and 42 subjects gave correct answers on FB2. They had more errors FB2 than FB1 (p=.02). In the case of FB1, significant differences were not accepted between correct answered subjects and incorrect answered subjects by score of LASMI-I. In the case of FB2, significant differences were found by LASMI-I overall score (p=.01) and ‘Conversation’ score (p=.01), and ‘Group activity’ score(p=.03). From this, interpersonal functioning of schizophrenic subjects who answered correctly were better than subjects who answered incorrectly. Subjects who answered correctly in FB2 had a shorter time of TMT-B required than subjects who answered incorrectly (p<.01). No significant differences were found in FB1 (p=.21). Subjects who answered correctly in FB2 seemed that they had better functioning of Working memory than subjects who answered incorrectly.

LASMI-I ‘Conversation’ score (rs=.30) were significantly correlated with TMT-B time (p<.01). TMT-B were significantly correlated with ‘Clarity of conversation’ (rs=.34) and ‘Understanding’ (rs=.38), these were domains of ‘Conversation’ of LASMI-I. As the subjects had a good function of the working memory, an interpersonal functioning was good.

<Discussion>

It was confirmed that ToM and Working memory were related to the interpersonal functioning of the person with schizophrenia. It was thought that ToM influenced interpersonal functioning; brightness and the initiative of the conversation, circumstantial judgement and understanding, appropriate reply and claim, furthermore autogenous relationships with associates, friends, and the opposite sex. It was suggested that it was necessary to intervene in that understanding with more than of second-order was promoted, because the understanding with more than of second-order promotes the understanding of a social concept and interpersonal relationships and the feelings between the characters such as a novel or a drama. The understanding with more than of second-order needs to maintain much information more than understanding of first-order, and to handle. It was thought intervention is necessary that promote the understanding of complicated Theory of Mind and raise a function of Working memory in order to improve the interpersonal function of the person with schizophrenia.