Emotion recognition, ‘theory of mind,’ and social behavior in schizophrenia
Introduction
The term ‘schizophrenia’ refers to a group of psychotic disorders that are characterized by cognitive symptoms such as thought disorder and delusions, and by behavioral symptoms such as catatonia or negative symptoms (American Psychiatric Association, 1994).
From a clinical perspective, the most outstanding characteristic of schizophrenia is the inapt, often bizarre behavior of affected individuals. In other words, it is almost always the deviant social behavior in schizophrenia that renders patients ‘abnormal.’ The importance of social behavioral problems in schizophrenia cannot be overestimated, since impaired social functioning in schizophrenic patients frequently precedes the onset of psychosis. Social deficits are often already present in first-episode patients, and may be relatively impervious to antipsychotic treatment. Moreover, social impairments in schizophrenia frequently worsen over the course of the disorder and probably contribute to the rate of relapse (recently summarized by Pinkham et al., 2003).
Over the past decades, however, most neuropsychiatric studies in schizophrenia have largely focused on disorders of ‘nonsocial’ cognitive processes such as executive functioning, attention, or memory (e.g., Evans et al., 1997, Cirillo and Seidman, 2003), deficits that certainly affect patients' psychosocial skills. Only quite recently have researchers shifted their attention towards social cognition in schizophrenia (Penn et al., 1997, Pinkham et al., 2003), questioning to what extent an impaired perception of social signals or impaired social cognition may directly account for the poor social functioning in schizophrenia. There is indeed some evidence that, statistically, social cognitive measures may better distinguish between patients and nonpatients than ‘nonsocial’ tests (Penn et al., 1997). The association of social perceptual and cognitive skills in schizophrenic patients with patients' actual social behavior is, however, to a certain extent still unclear (overview in Brüne, in press). It seems to turn out that patients with chronic schizophrenia suffering from marked negative symptoms are more impaired in their ability to recognize emotions from facial expressions and in their social skills, relative to less chronic patients (Mueser et al., 1996, Penn et al., 1996).
With regard to social cognition, a compelling theoretical framework to explain certain cognitive aspects of the marked social deficits in schizophrenia was put forward by Frith (1992). He hypothesized that many symptoms typical of schizophrenia may be accounted for by a specific cognitive incapacity of schizophrenic patients to accurately attribute mental states to themselves or others (commonly referred to as ‘having a theory of self and others' minds’; ToM), leading to what Frith called ‘disorders of willed action,’ ‘disorders of self-monitoring,’ and ‘disorders of monitoring other persons' thoughts and intentions’ (Frith, 1992). For example, if patients with schizophrenia have difficulties in perceiving their behavior as the result of their own enacted goals or to suppress inappropriate responses, their behavior may become disorganized. Secondly, if patients are unable to appreciate their behavior as the result of their own intentions, they may falsely interpret their actions as being under alien control or experience voice-commenting hallucinations. Thirdly, if patients confuse their subjective representations with reality, they may maintain false beliefs about other people's intentions, for instance, in the form of delusional convictions of being poisoned or persecuted.
Frith and Frith (1999) have proposed that the perception of emotional states of other individuals is represented in a dedicated brain system different from (though overlapping with) a second one subserving ToM. The former involves a ‘ventral’ stream including the amygdala and the orbitofrontal cortex; the latter, a ‘dorsal’ pathway comprising the superior temporal sulcus, the inferior frontal regions, and the medial prefrontal cortex including parts of the anterior cingulate cortex (Frith and Frith, 1999, Frith and Frith, 2001).
With respect to schizophrenic disorders, there is a host of studies providing evidence that schizophrenic patients are profoundly compromised in recognizing other people's emotions from facial expressions, gestures, or voices (reviewed in Mandal et al., 1998), and in inferring the mental states of others (i.e., ToM; overview in Brüne, in press). Many studies suggest that the deficits in these domains are specific rather than secondary to a general cognitive decline in schizophrenia (e.g., Bryson et al., 1997, Langdon et al., 1997).
Emotion recognition and ToM have, however, not been assessed simultaneously in adults with schizophrenia so far. Moreover, only a few studies have directly focused on the question as to whether patients' compromised social perceptual skills account for their actual social behavioral problems, and only one study has looked at ToM and its relation to social behavior in schizophrenia (Roncone et al., 2002).
The present study attempts to clarify the following hypotheses: (1) compared with healthy controls, patients with schizophrenia are impaired in both emotion recognition and ToM tasks; (2) the performance on social cognitive tasks contributes a significant proportion of the amount of variance to distinguish between patients and controls, the amount of variance being possibly greater than that of nonsocial task performance; and (3) measures of social perception and cognition contribute to explain patients' actual social behavioral abnormalities.
Section snippets
Participants
Twenty-three schizophrenic patients (18 males, 5 females) with schizophrenia according to DSM-IV (American Psychiatric Association, 1994) who were treated as in-patients or attended a day clinic and who had given informed consent to participate were included. All patients received antipsychotic medication. Patients' mean age at onset of the disorder was 26.5 years (12–59 years; S.D.±10 years), and their mean duration of illness was 12.3 years (0–35 years; S.D.±7.9 years). Eighteen healthy
Between-group differences
Since IQ measures and age were normally distributed, a parametric one-way analysis of variance (ANOVA) was carried out. Patients did not differ from controls with respect to age [F(1,40)=0.719, P=0.402] or ‘crystallized’ verbal IQ [F(1,40)=2.322, P=0.136].
Due to large differences between the groups in amount of variance, Kruskal–Wallis nonparametric tests were carried out to compare patients' and controls' performance on the executive functioning and the social perception and cognition tasks.
Discussion
This study investigated ‘crystallized’ verbal intelligence, executive functioning, and social perception and cognition in patients diagnosed with schizophrenia. Special emphasis was put on the relation of these cognitive functions to psychopathology and the actual social behavior of patients with schizophrenia. All three predictions were confirmed. As expected and demonstrated in a number of previous studies, patients with schizophrenia were impaired relative to healthy control subjects on all
Acknowledgement
I am grateful to Luise Bodenstein and Farwa Karimi for their support in assessing patients and control subjects. Thanks also to Hans Burmeister, Gisela Notthoff, Sandra Richards, Wolfgang Rohmann, Helmuth Schrader, and Monika Stein for their time and effort in rating patients' social behavior. I am also indebted to all patients and control persons for their willingness to participate.
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