[Deficit of the theory-of-mind in schizophrenia: clinical concept and review of experimental arguments]

Theory of mind functioning in mentally disordered offenders detained in high security psychiatric care: its relationship to clinical outcome, need and risk

BACKGROUND

Theory of mind (ToM) refers to the cognitive mechanisms that allow us to infer our own mental states and those of others. Whilst ToM deficits are frequently observed among individuals with schizophrenia, little is known about their relationship to functional outcome.

AIMS

Among patients with schizophrenia in a high security hospital, to test whether ToM performance, in relation to other cognitive and clinical variables, is related to measures of subsequent clinical outcome.

METHODS

ToM was assessed using the modified advanced test (MAT) and the revised eyes task (RET). Outcome, including ongoing need and risk, was assessed using the HoNOS secure, CANFOR and HCR-20 respectively three years post ToM assessment.

RESULTS

Performance on the RET was the only variable to be significantly correlated with the symptom ratings of the HoNOS secure and the HCR-20 total scores. Performance on the RET also accounted for approximately half of the variance in the CANFOR ratings and a third in the risk management item ratings of the HCR-20. Age, number of years diagnosed with schizophrenia and other aspects of cognition were also significantly correlated with the HoNOS security scale.

CONCLUSIONS

The results suggest that social perceptual ToM may be a useful prognostic indicator, but also that ToM impairments may represent an unmet need. Replication of the work with larger and more diverse samples of people with schizophrenia is necessary, as well as trials of therapeutic effort directed at improvement of ToM impairments.

A study of theory of mind in a group of schizophrenic patients using a mental verb extension task

An individual has a theory of mind (ToM) if he imputes mental states to himself and others and applies this system to make predictions about the behaviours of others. Findings of cognitive impairment could help us to understand faulty processing mechanisms in schizophrenia. The proposition is that individuals with schizophrenia may be unable to internalize adequately the points of view of others. We tested 27 schizophrenic patients (ICD; WHO). The positive and negative symptom scale (PANSS) was used to assess psychopathology, and the three ToM tasks--first- and second-order false belief tasks and the mental verb extension task--were administered to each subject. Patients who perform well on the ToM first and second order stories do not show problems in the verb extension task. However, the mistakes made in the first and second order stories are also reflected in the verb extension task. The group having difficulties with the first-order story presented more problems in the mental verbs task than the group showing difficulties with the second-order story. This leads us to conclude that the impairments found on the first-order false belief task are more severe and profound than those on the second-order task, and such specific deficits are also seen in the organization of verbs of knowing. It would seem that some schizophrenic patients do not impute mental states to themselves and others, and therefore use the mental verbs wrongly.

Do you see what I see? Interpretations of intentional movement in schizophrenia

OBJECTIVE

Current literature exploring theory of mind (ToM) abilities in patients with schizophrenia has failed to take into account the dynamic nature of complex social interactions. The aim of this study was to explore symptom specific impairments in theory of mind using a novel, dynamic task.

METHODS

Subjects viewed short animations displaying three types of movement; random, goal directed, and socially complex (theory of mind). Verbal descriptions of the animations were obtained from 61 patients with schizophrenia (divided into symptom sub-groups) and 22 healthy comparison subjects and were scored for accuracy, type of response and use of target terms (terms most appropriate to each animation type).

RESULTS

Accuracy on all three conditions discriminated behavioural signs (BS), and (to a lesser degree) paranoid subjects, from the other schizophrenia sub-groups (those in remission and those with passivity features) and the controls. Paranoid and BS groups had difficulties with all the animations, yet all symptom sub-groups failed to use the appropriate mentalising language to describe the ToM animations.

CONCLUSIONS

In this first exploration of on-line mentalising abilities in schizophrenia, it is suggested that a failure to use appropriate mentalising language may be a trait marker for the disease. The nature of the type of tasks used to assess social cognitive processing in this group needs careful consideration, and tasks tapping into the fluidity of social interactions yield results that differ from previously reported studies.

[Visuospatial context processing in untreated schizophrenic patients and relation to disorganization syndrome]

AIM

Previous studies on schizophrenia have suggested that context-processing disturbances were one of the core cognitive deficits present in schizophrenia. Schizophrenic patients have a failure either of inhibition strategy and maintenance of visuospatial information (25) in condition of contextual interference. In the present study, we explored the performances of untreated schizophrenic patients with 2 tasks exploring detection and long term retention of complex visual features and field dependence-independence tasks were selected. These abilities involve temporary maintenance of visuospatial information and executive functioning of visual working memory system. Several studies have shown that cognitive deficit may depend on schizophrenic symptomatology. However results remain controversial in determining the specific influence of negative and positive symptomatologies as well as clinical disorganization. Our goal was to explore the processing of spatial context and its relation to disorganized syndrome. This study was approved by the local ethic committee.

METHODOLOGY

Thirty-six schizophrenic patients were included according to DSM IV criteria (19 neuroleptic naïve, 17 unmedicated patients during more than 3 months). Thirty-six healthy controls were matched to patients for age, gender and level of education. Absence of axis 1 pathology was attested for controls with SCID-NP. Current symptomatology was evaluated by the Positive and Negative Syndrome Scale (PANSS) (14). Clinical disorganisation was evaluated with the disorganisation score established upon a factorial analysis of PANSS by Lepine and Lançon. Items selected to distinguish the disorganised group were abstraction, disorganization, orientation, and attention.

PROCEDURE

Two tasks of embedded figures were administered individually to patients and controls. The Faverge task (Research of Figures-RF) (10) evaluates the ability to recognize the target from spatial complex geometrical figures. The Group Embedded Figure Task (GEFT - Oltman) assesses the detection and maintenance of visual target and its recognition within a complex figure. Performance between patients and controls were compared with the Student T test. The comparison of two clinical subgroups of disorganized and low disorganized patients and control group was performed with an ANOVA. Tuckey test was used for pairwise comparisons.

RESULTS

We defined two subgroups of patients, disorganized patients (subscore 12, n=17) and low disorganized patients (subscore<12, n=19). Theses 2 subgroups were similar for age and level of education. Concerning the two tasks, there was no significant difference between schizophrenic patients and normal controls. The comparison between subgroups of disorganized and low disorganized patients, for RF task, showed a decrease of correct answers with disorganized patients (p<0.05). For GEFT task, disorganized patients had a decrease of correct answers p<0.01) and more errors (p<0.01) and omissions (p<0.05). The low disorganized patients exhibited for the two tests comparable performance to controls. The disorganized patients had a decrease of right answers (p<0.05) and more errors (p<0.05) than controls for GEFT task and no significant difference for RF. However, with IQ (evaluated with an abstract reasoning test) introduced as covariate, only correct answers for GEFT task remain significant (p<0.05).

DISCUSSION

The weak performance of disorganized schizophrenic patients for two tasks RF and GEFT showed that treatment of visuospatial information was impaired in the first perceptive phase of selection and in the organization of information (RF), especially with the maintenance of visual information in memory (GEFT). By contrast, low disorganized patients demonstrated a correct analytic treatment of elementary processing and visuospatial working memory.

CONCLUSION

The severity of disorganization influences the visuospatial context processing and visuospatial working memory. These results show the heterogeneity of cognitive functioning regarding to schizophrenic symptomatologies. This difficulty could be related to a problem of central executive functioning in the visuospatial component of working memory, possibly mediated by the dysfunction of dorsolateral prefrontal cortex.

Theory of mind and the role of IQ in chronic disorganized schizophrenia

BACKGROUND

Several studies have suggested a theory of mind (ToM) deficit in schizophrenic disorders. However, the role of interfering variables such as IQ, attention, memory, and severity of the disorder has remained ambiguous.

METHODS

A theory of mind picture story comprising a sequencing task, a first and a second order false belief test, and a tactical deception test was given to a group of 23 patients with chronic disorganized schizophrenia and to 12 healthy control persons. In addition, a nonsocial picture story had to be sequenced. Severity of the psychopathology was measured by using the brief psychiatric rating scale (BPRS), IQ was estimated using the 'Mehrfachwahlwortschatztest' (MWT, multiple choice verbal comprehension test).

RESULTS

The schizophrenic group was impaired relative to controls on the theory of mind task, but not on the sequencing task of the nonsocial picture story. However, when controlled for IQ, no such difference was found. These findings were neither related to severity, duration, nor age at onset of the disorder.

CONCLUSIONS

Theory of mind deficits in schizophrenia may be related to domain general impairments, e.g., intelligence and working memory load, rather than reflecting a 'genuine' compromised mental state attribution similar to autistic spectrum disorders. Schizophrenic patients may, however, rather be impaired in how and when to apply strategic social reasoning. Further studies to investigate the nature of social deficiency in schizophrenia are warranted.

Neural network models of schizophrenia

There is considerable neurobiological evidence suggesting that schizophrenia is associated with reduced corticocortical connectivity. The authors describe two neural network computer simulations that explore functional consequences of these abnormalities. The first utilized an "attractor" neural network capable of content-addressable memory. Application of a pruning rule that eliminated weaker connections over longer distances produced functional fragmentation and the emergence of localized, "parasitic" attractors that intruded into network dynamics. These pathologies generally were expressed only when input information was ambiguous and provide models for delusions and cognitive disorganization. A second neural network simulation examined effects of corticocortical pruning in a speech perception network. Excessive pruning caused the network to produce percepts spontaneously, that is, in the absence of inputs, thereby simulating hallucinations. The "hallucinating" network also demonstrated subtle impairments in narrative speech perception. A parallel study of human patients found similar impairments when comparing hallucinating patients with nonhallucinating patients. In addition, the authors have used transcranial magnetic stimulation (TMS) to directly probe speech perception neurocircuitry in patients with these hallucinations. As predicted by the neural network model, the authors confirmed that "suppressive" low-frequency TMS reduces auditory hallucinations. Neural network simulations provide empirically testable concepts linking phenomenological, cognitive, and neurobiological findings in schizophrenia.