Gildas Brébion

Recognition accuracy and response bias to happy and sad facial expressions in patients with major depression.

Impaired facial expression recognition has been associated with features of major depression, which could underlie some of the difficulties in social interactions in these patients. Patients with major depressive disorder and age- and gender-matched healthy volunteers judged the emotion of 100 facial stimuli displaying different intensities of sadness and happiness and neutral expressions presented for short (100 ms) and long (2,000 ms) durations. Compared with healthy volunteers, depressed patients demonstrated subtle impairments in discrimination accuracy and a predominant bias away from the identification as happy of mildly happy expressions. The authors suggest that, in depressed patients, the inability to accurately identify subtle changes in facial expression displayed by others in social situations may underlie the impaired interpersonal functioning.

Positive symptomatology and source-monitoring failure in schizophrenia - an analysis of symptom-specific effects

Recent research has suggested that certain positive symptoms in patients with schizophrenia are linked to self monitoring/reality-monitoring deficits. We wished to investigate the association between such deficits and three specific symptoms: hallucinations, delusions and thought disorganisation. Forty patients with schizophrenia and 40 normal controls were administered a source-monitoring task. Twenty-four items were produced, either verbally by the experimenter, or verbally by the subject, or presented as pictures. Then, subjects were read a recognition list including the produced target items mixed with distractors. They were required to recognise the target items and to remember their source of production. The pattern of memory deficits has previously been reported (Brébion, G., Smith, M., Gorman, J., Amador, X., 1997. Discrimination accuracy and decision biases in different types of reality monitoring in schizophrenia. Journal of Nervous and Mental Disease 185, 247-253). The current analyses focussed on the false recognition of distractors, and on the errors in the source attribution of the recognised target items. Results showed that higher hallucination scores were associated with an increased tendency towards false recognition of non-produced items. In addition, hallucinators were more prone than control subjects to misattribute to another source the items they had produced themselves. Furthermore, hallucinators and delusional patients were more prone than the other patients to report that spoken items had been presented as pictures. This latter finding suggests that both hallucinations and delusions are associated with confusion between imagined and perceived pictures. Our previous report stated that only one of the three investigated types of response bias was associated with global positive symptomatology. However, this finer-grained analysis revealed that the three of them were in fact associated with hallucinations and/or delusions. On the other hand, thought disorganisation appeared to be independent from these mechanisms.

Source monitoring impairments in schizophrenia: characterisation and associations with positive and negative symptomatology

This article describes a consistent pattern of the associations between source monitoring failure and clinical symptomatology in schizophrenia. The associations with positive symptoms in this sample have been reported previously, but not the associations with negative symptoms. Forty patients with schizophrenia were administered several memory tasks including free recall of lists of words, recognition and source memory. Various memory errors assumed to stem from source monitoring failure were derived. They include intrusions and recall of words from previous lists in free recall, false recognitions, and confusion with regard to the source of the stimuli. We studied the associations of these memory errors with positive symptoms and with a broad range of negative symptoms. All the memory errors were positively associated with at least one positive symptom. On the other hand, these errors were inversely associated with certain negative symptoms reflecting lack of emotion or lack of social interactions. Thus positive and negative symptomatology appear to have opposite links to the source monitoring errors observed in patients with schizophrenia. Cognitive mechanisms leading to different types of source monitoring errors and possibly to the formation of positive symptoms are discussed.

Memory impairment and schizophrenia: the role of processing speed

A link between slowing of processing speed and cognitive disorders, including memory, has repeatedly been found in research on aging, and suggested in other cognitively impaired populations. We tested the hypothesis that a link between memory impairment and slowing of processing speed would also be observed in schizophrenia. Forty-four schizophrenic patients and 40 normal controls were administered a memory task involving free recall and recognition. Processing speed was assessed by the Digit Symbol Substitution Test. Working memory span was assessed as well. The measure of processing speed was consistently correlated with the various memory measures in patients, including efficiency of encoding. These correlations remained significant, or tended to be significant, when working memory span was partialled out. Memory deficits observed in schizophrenia may thus be partly accounted for by a slowing of processing speed. It is suggested that research on cognitive deficits in this and other mental diseases focus more on processing speed.

Theory of mind deficits in chronic schizophrenia: Evidence for state dependence

There is evidence that people with schizophrenia show specific deficits in theory of mind (ToM). However, it is a matter of debate whether these are trait or state dependent, and the nature of the relationship between ToM deficits and particular symptoms is controversial. This study aimed to shed further light on these issues by (1) examining ToM abilities in 61 individuals with chronic schizophrenia during a stable phase as compared with 51 healthy controls matched by gender, age, educational level and current IQ, and (2) exploring the relationship between ToM and symptoms. Second order verbal stories and a non-verbal picture-sequencing task were used as ToM measures. Results showed no differences in ToM performance between patients and controls on either measure. Subsequent subgrouping of patients into remitted and non-remitted showed a worse performance of non-remitted patients only on second order ToM tasks. Specific ToM deficits were found associated with delusions. Association with negative symptoms was found to be less specific and accounted for by illness chronicity and general cognitive impairment. The results from the present study are in line with models which hypothesise that specific ToM deficits in schizophrenia are state dependent and associated with delusions. Such associations may also be task specific.

Semantic organization and verbal memory efficiency in patients with schizophrenia

The role of semantic organization in verbal memory efficiency in schizophrenia was investigated. Patients and healthy controls were administered a free-recall task involving 1 nonsemantically organizable list, 1 list organizable in semantic categories with typical instances, and 1 list organizable in semantic categories with atypical instances. Reduced semantic organization was observed in patients. Regression analyses showed that the semantic clustering score in the atypical organizable list made a significant contribution to recall performance in patients. When semantic clustering was controlled, the effect of diagnosis on free recall was significant. These results suggest that depth of semantic organization is a crucial factor of verbal memory performance in schizophrenia. However, semantic organizational deficit does not account for the whole recall impairment.

Memory and schizophrenia: differential link of processing speed and selective attention with two levels of encoding

The purpose of this study was to investigate how underlying cognitive deficits such as a defect in processing speed or in selective attention contributed to different types of memory impairment observed in schizophrenia (superficial vs deep encoding). 49 schizophrenic patients and 40 normal controls were administered a verbal memory task. Superficial encoding was assessed by the ability to recall items in their serial order. Deep encoding was assessed by the ability to organise words into semantic categories. Two measures of processing speed (Digit Symbol Substitution Test and Stroop colour time) and one measure of selective attention (Stroop test) were used. Regression analyses were carried out. In the patient group, processing speed contributed to both superficial and deep encoding, and to a global verbal memory score. Selective attention only contributed to the superficial encoding processes. Thus, slowing of processing speed in schizophrenia seems to be more crucial for memory performance, since it affects memory in a pervasive way.

Discrimination accuracy and decision biases in different types of reality monitoring in schizophrenia.

A reality monitoring task was administered to 31 schizophrenic patients and 31 normal controls. Twenty-four items were produced, either orally by the experimenter, orally by the subjects, or seen as pictures. Subjects were later read a list of 48 items and were asked to indicate if each item was new, self-generated, experimenter-generated, or presented as a picture. Results showed that schizophrenic patients were impaired in discriminating old items from new, with a higher bias than controls toward reporting new items as if they were old (false alarms). In addition, patients were impaired in discriminating self-generated items from externally generated items, with a higher bias than controls toward attributing self-generated items to an external source. Lastly, they were significantly impaired in discriminating the modality (auditory versus visual) in which the event was presented. The bias toward remembering orally produced items as pictures was correlated with positive symptomatology and was significantly higher than controls in patients with high levels of positive symptoms. This suggests that mental imagery may play a role in positive symptomatology. These results demonstrate the relevance of studying decision biases along with discrimination performance for the understanding of the mechanisms of reality monitoring impairment in schizophrenia.

Word recognition, discrimination accuracy, and decision bias in schizophrenia: association with positive symptomatology and depressive symptomatology.

The purpose of this experiment was to replicate and extend to a memory task Bentall and Slades (1985) finding that hallucinations in schizophrenic patients were linked to a liberal decision bias. A word recognition task was administered to 40 schizophrenic patients and 40 normal controls that yielded two indices of performance: an index of discrimination accuracy (Pr) and one of decision bias (Br). Patients obtained a lower Pr than controls, whereas Br was similar in both groups. In patients, Br was selectively correlated with positive symptomatology: the more the positive symptoms, the more liberal the bias. In particular, there was a specific correlation between decision bias and hallucinations. Conversely, Pr was inversely correlated with severity of depression, but not with either positive or negative symptoms. Thus, positive symptomatology may be linked more to difficulties in distinguishing between representations of internal versus external events than to deficits in encoding external events.

Opposite links of positive and negative symptomatology with memory errors in schizophrenia

We wished to confirm and extend a previous correlational study of our group, suggesting that positive symptoms in schizophrenia were linked to an increase in certain types of memory errors, and negative symptoms to a decrease in other types of errors. A post-hoc analysis was conducted in 33 schizophrenic patients and 40 normal control subjects on memory errors collected in a free recall task and two types of recognition tasks. The memory errors were intrusions and list errors in free recall, and decision bias towards false alarms in recognition, all assumed to reflect a source-monitoring failure. In a first analysis, the patient sample was split along the median for positive symptoms as rated by the Scale for the Assessment of Positive Symptoms (SAPS). In a second analysis, it was split along the median for negative symptoms as rated by the Scale for the Assessment of Negative Symptoms (SANS). Patients with high ratings of positive symptoms made more memory errors (intrusions, list errors, false alarms) than those with low ratings, supporting the hypothesis of a link between positive symptomatology and source-monitoring failure. On the other hand, patients with high ratings of negative symptoms made fewer of these errors than the other patients. Fewer errors were specifically associated with more affective flattening, alogia and anhedonia, whereas avolition was entirely unrelated to them.