François Guillem

The dimensional symptom structure of schizophrenia and its association with temperament and character

Recent studies suggest that personality may influence symptom expression and social functioning in schizophrenia. This study investigated the relationships between personality and symptom dimensions in schizophrenia patients. Fifty-two schizophrenia patients and 25 five healthy subjects were assessed using the Temperament and Character Inventory (TCI). The patients were also assessed for positive and negative symptoms using SAPS and SANS and scored according to Andreasens (1995: Andreasen, N.C., Arndt, S., Alliger, R., Miller, D., Flaum, M. 1995. Symptoms of schizophrenia. Methods, meanings, and mechanisms. Arch. Gen. Psychiatry, 52, 341-351) classical three dimensional model and by the five dimensional model of Toomey et al. (1997: Toomey, R., Kremen, W.S., Simpson J.C., Samson, J.A., Seidman, L.J., Lyons, M.J., Faraone, S.V., Tsuang, M.T. 1997. Revisiting the factor structure for positive and negative symptoms: evidence from a large heterogeneous group of psychiatric patients. Am. J. Psychiatry, 154, 371-377). Comparisons between patients and controls revealed significant differences on various TCI scores consistent with a global disorganization of personality in schizophrenia involving both basic neurophysiological and potentially genetically determined traits (i.e. temperament) and developmental aspects of personality (i.e. character). Correlation analysis showed distinct associations between symptoms and personality dimensions. The results suggest that the negative and disorganized dimensions of schizophrenia are related temperamental factors, whereas the psychotic symptoms are more related to characterological abnormalities. The observed patterns of associations also underline the heterogeneity of the classical negative and positive dimensions of schizophrenia.

Gender Differences in Memory Processing: Evidence from Event-Related Potentials to Faces.

This study investigated gender differences on memory processing using event-related potentials (ERPs). Behavioral data and ERPs were recorded in 16 males and 10 females during a recognition memory task for faces. The behavioral data results showed that females performed better than males. Gender differences on ERPs were evidenced over anterior locations and involve the modulation of two spatially and temporally distinct components. These results are in general accordance with the view that males and females differ in the cognitive strategies they use to process information. Specifically, they could differ in their abilities to maintain information over interference and in the processing of the intrinsic contextual attributes of items, respectively, associated with the modulation of two anterior components. These interpretations lend support to the view that processing in females entails more detailed elaboration of information content than in males. Processing in males is more likely driven by schemas or overall information theme.

Rivastigmine treatment as an add-on to antipsychotics in patients with schizophrenia and cognitive deficits

ABSTRACT Objective: Although new atypical antipsychotic agents have been found to improve overall cognitive function in patients with schizophrenia (SZ), some aspects of memory, attention and executive functions still remain impaired. Acetylcholinesterase (AChE) inhibitors, such as rivastigmine, have been shown to improve cognition in other disorders, particularly Alzheimers disease. Dysfunctions in cholinergic systems, especially in the prefrontal cortex, have been identified in SZ, suggesting that cholinesterase inhibitors may be effective in treating cognitive deficits in this disease. Research design and methods: Using a randomized crossover design, we assessed SZ patients with stable symptoms and poor cognitive functioning. Fifty-eight patients with memory deficits, according to subjective complaints or based on clinicians’ observations, were assessed with the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and Subjective Scale to Investigate Cognition in Schizophrenia (SSTICS). Only 24 of these subjects met the inclusion criteria. Twenty patients took part in the study (four dropped out). All subjects meeting the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM‑IV) criteria for SZ were maintained on their current antipsychotic medication (18 atypicals and two typicals) and were randomly assigned to treatment with rivastigmine. Dosage was a function of tolerability, beginning at 3 mg/day and progressively increasing to 9 mg/day. Subjects were given the Cambridge Neuropsychological Test Automated Battery (CANTAB) at baseline and 3 and 6 months. Results: The results revealed no significant improvement in any of the cognitive variables investigated following rivastigmine treatment and symptom severity scores remained unchanged over all recorded time periods. Conclusion: Rivastigmine treatment did not appear to enhance cognition in SZ patients with important cognitive impairments. This finding needs to be interpreted with care and requires substantiation with larger sample size studies with patients treated with cognitive enhancer for longer periods.

Relationship between psychotic and obsessive compulsive symptoms in schizophrenia.

The presence of obsessive compulsive symptoms (OCSs) in schizophrenia was recognized as early as the first descriptions of the illness. Studies investigating the association between OCSs and schizophrenia have defined their co-occurrence in terms of co-morbidity and compared schizophrenia patients separated into groups according to whether they presented OCSs or not. However, most of these studies did not take both the complexity of the schizophrenia phenomenology and that of OCSs into account. The present research investigates the relationship between schizophrenia symptoms and OCSs using a correlational approach with a dimensional perspective in order to determine how the OCSs contribute to symptom expression in schizophrenia. Fifty nine schizophrenia patients were rated for schizophrenia symptoms (SAPS-SANS) and OCSs (Y-BOCS). Schizophrenia symptoms scores were collapsed into four dimensional scores and OCSs into for other dimensional scores. The latter were entered as explanatory variables to determine their associations with schizophrenia dimension scores using series of stepwise regression models. The results showed a strong positive relationship between Delusions and Obsessions consistent with the view that they reflect manifestations of the similar mechanisms. Similar results indicate an association between Auditory hallucinations and Compulsions also suggesting that they share common mechanisms. On the other hand, there were inverse relationships between Somatic Obsessions and Disorganization and between Hoarding/Collecting Compulsions and Delusions or Auditory hallucinations. These results may reflect that these OCSs have a protective effect against disorganization and psychotic symptoms respectively.

The cognitive and anatomo-functional basis of reality distortion in schizophrenia: A view from memory event-related potentials

This study investigated the neural and cognitive correlates of reality distortion in schizophrenia by using event-related potentials (ERPs) recorded in a recognition memory task for face. This task has been chosen because previous studies have shown that it provides distinct indices related to specific cognitive processes and to the functioning of specific brain regions. ERPs have been recorded in controls and schizophrenia patients separated into high scorers (RD+) and low-scorers (RD-) according to their Reality Distortion score (hallucination and delusion SAPS subscales). The results indicate that RD+ presents abnormalities on various cognitive processes. First, RD+ are deficient at interference inhibition and knowledge integration (reduced P2a and N400 effect). The similar impairments found in RD- suggest that they represent basic traits of the illness. Second, RD+ showed inappropriate stimulus categorization and contextual integration (larger N300 and fronto-central effect). Third, RD+ showed a late index (P600 effect) not different from controls, but larger than in RD-. This result is consistent with a qualitative, rather than quantitative, impairment of mnemonic binding processes (inappropriate binding) in RD+. Since each of the ERP abnormalities observed represents associated with distinct brain dysfunction, the results are further discussed in regard of the respective contribution of the parietal, frontal and hippocampal structures to reality distortion symptoms.

Memory impairment in schizophrenia: a study using event-related potentials in implicit and explicit tasks.

Although memory impairment is recognized as a major fact of schizophrenia, only a few studies have investigated memory impairments with specifically designed event-related potential (ERP) protocols. In this study, ERPs were recorded from 15 schizophrenia patients and 15 matched control subjects during implicit and explicit memory tasks for unfamiliar faces. The results showed that patients have a reduced modulation of an N400-like component in both the implicit and explicit tasks that suggests a deficient integration of incoming information with personal knowledge. Patients also displayed an enhanced frontally distributed activity in the explicit task that may represent an impairment in the integration of intrinsic contextual information, a disturbance in the ability to inhibit proactive interference or a combination of both processes. Finally, the modulation of the late positive component did not differ from that in control subjects in both implicit and explicit tasks, suggesting that the impairment in mnemonic binding processes suggested in schizophrenia is more qualitative, i.e. incomplete or inappropriate, due to the anomalies in antecedent processes. The correlations observed between impairments of ERP modulation and symptoms further support these interpretations.

The relationships between symptom dimensions and dysphoria in schizophrenia

Previous studies have suggested that qualitatively distinct aspects of dysphoria (anxiety and depression) are related to specific dimension of schizophrenia symptomatology. Most of these studies used simple dimensions and dysphoria models, although finer distinctions could help defining specific relationships. This study examined the relationships of distinctive aspects of depression and anxiety (both state and trait) with symptom dimensions. Forty patients with a DSM-IV diagnosis of schizophrenia were assessed for symptoms (SAPS-SANS), trait and state anxiety (STAI) and depression (CDS). Symptoms ratings were summarized as dimensional scores according to a two-, three- or five-dimensional models proposed in the literature. The correlation analysis replicates previous observations that distinct aspects of dysphoria are associated with specific dimensions of schizophrenia, with the exception of disorganization. Moreover, controlling for intercorrelated variables revealed that schizophrenia and dysphoric symptoms might act in combination and/or through indirect links to contribute to illness expression. Our data further suggested that these associations may be best understood in terms of interactions between various processing biases alluded in the most recent cognitive accounts of schizophrenia symptoms.

Sex differences in memory processing in schizophrenia: An event-related potential (ERP) study

Recently, research has begun to examine sex differences in cognitive functions in schizophrenia and whether such sex differences reflect normal, exaggerated, or reversed sexual dimorphism. This study examined this question by using event-related potentials (ERPs). ERPs were recorded in a recognition memory task in 18 patients and 18 matched control subjects. On an early frontal component, the results show an interaction between sex and pathological condition that results in an apparent reversed sexual dimorphism. On mid-latency components, patients show no sex difference on a frontal component, but a difference on the posterior component, whereas healthy subjects show a reverse pattern. Finally, late components show sex difference in the same direction as healthy subjects. These results indicate that the influence of sex on the cognitive impairment in schizophrenia is not homogenous across the information-processing cascade.

Event‐related potentials differentiates the processes involved in the effects of sleep on recognition memory

This study examined the role of sleep on event-related potential (ERP) indicators of memory following sleep and wake. We expected a larger ERP effect due to a facilitory effect of sleep on memory. During the study session, subjects memorized a series of stimuli (faces). At test, after a retention interval characterized by either sleep or by normal waking activities, subjects were asked to recognize old items intermixed with new. Results revealed differences in the old/new effect whereby the amplitude between old/new items was larger after sleep versus wake, suggesting a role of sleep in consolidation. Retention over sleep versus wake was associated with modified early and late frontal and posterior components possibly manifesting reduced interference inhibition, increased contextual processing, and facilitation of episodic memory. These findings suggest that ERP indices are differentially affected by sleep, reflecting differences in memory processing.

ERP investigation of study-test background mismatch during face recognition in schizophrenia

Old/new effects on event-related potentials (ERP) were explored in 20 patients with schizophrenia and 20 paired comparison subjects during unfamiliar face recognition. Extrinsic perceptual changes - which influence the overall familiarity of an item while retaining face-intrinsic features for use in structural face encoding - were manipulated between the study phase and the test. The question raised here concerns whether these perceptual incongruities would have a different effect on the sense of familiarity and the corresponding behavioral and ERP measures in the two groups. The results showed that schizophrenia patients were more inclined to consider old faces shown against a new background as distractors. This drop in face familiarity was accompanied by the disappearance of ERP old/new effects in this condition, i.e., FN400 and parietal old/new effects. Indeed, while ERP old/new recognition effects were found in both groups when the picture of the face was physically identical to the one presented for study, the ERP correlates of recognition disappeared among patients when the background behind the face was different. This difficulty in disregarding a background change suggests that recognition among patients with schizophrenia is based on a global perceptual matching strategy rather than on the extraction of configural information from the face. The correlations observed between FN400 amplitude, the rejection of faces with a different background, and the reality-distortion scores support the idea that the recognition deficit found in schizophrenia results from early anomalies that are carried over onto the parietal ERP old/new effect. Face-extrinsic perceptual variations provide an opportune situation for gaining insight into the social difficulties that patients encounter throughout their lives.