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Sonia Dollfus

Publications and source records attributed to Sonia Dollfus.

18 recordsLinked to original sources
PubMed2006

Semantic hyperpriming in schizophrenic patients: increased facilitation or impaired inhibition in semantic association processing?

Previous studies analyzing semantic priming in schizophrenic patients have reported conflicting results. In the present study, we explored semantic priming in a sample of schizophrenic patients with mild thought disorders. We wondered if distinct cognitive processes, such as facilitation and/or inhibition, underlie semantic hyperpriming and are variously impaired in schizophrenic patients. Using a lexical decision task, we evaluated semantic priming in 15 schizophrenic patients (DSM-IV) with mild thought disorders and 15 healthy controls matched for sex, age, and education level. The task was designed to divide semantic priming into two additive components, namely facilitation effect and inhibition effect. One-sample t-tests were performed to investigate differences in semantic priming, facilitation, and inhibition within each group. ANOVAs were performed to compare the effects of semantic priming, facilitation, and inhibition between groups. Patients displayed greater semantic priming than controls (i.e., hyperpriming), but this was not due to increased facilitation in processing semantically related pairs. On the contrary, hyperpriming was the result of prolonged response time to process semantically unrelated pairs, corresponding to a requirement to inhibit unrelated information. We demonstrated semantic hyperpriming in stabilized schizophrenic patients with mild severity of symptoms. Thus, semantic hyperpriming may be an intrinsic feature of schizophrenia that is not related to the clinical state of patients. Semantic hyperpriming was due to an inhibition effect involved in processing semantically unrelated information not to increased facilitatory effect for related pairs.

Adult↗
PubMed2006

When a schizophrenic deficit becomes a reasoning advantage.

A deficit in context processing has been proposed to be one of the major deficiencies in schizophrenia. A demanding reasoning task, known to promote a very reproducible bias (i.e., a reasoning error) in healthy subjects, triggered by a misleading context, was administered in 26 schizophrenic patients and 26 healthy participants. Responses at random were checked by including an additional group of 11 schizophrenic patients who performed a control version of the task. We showed that patients presented a surprising imperviousness to the reasoning bias and had significantly better logical performances than their paired healthy participants. This finding demonstrates that there are some problem solving situations where disregarding contextual information, a cognitive deficit that usually impairs schizophrenic patients gives them a cognitive advantage over healthy controls.

Adult↗
PubMed2005

The saccadic component of ocular pursuit is influenced by the predictability of the target motion in humans.

Predictive control is an important aspect of the smooth pursuit eye movements: it has been shown that when the target motion is composed of a mixture of sinusoids of different frequencies it becomes unpredictable and there is a decline in gain for the lowest frequencies but not for the highest one. Using such a pseudo-random paradigm we studied the effect of predictability of the target motion on the saccadic component of pursuit. For both the saccadic and the smooth components of pursuit, we observed that the gains for the lowest frequencies were significantly lower than the gain for the highest frequency. Thus, predictability of the motion of a visual target seems to influence both the smooth pursuit component and the saccadic component of ocular pursuit in the same way.

Adult↗
PubMed2005

Olanzapine versus risperidone in the treatment of post-psychotic depression in schizophrenic patients.

OBJECTIVE: To compare the efficacy of two atypical antipsychotic drugs, olanzapine and risperidone, in schizophrenic patients with post-psychotic depression. RESULTS: A clinically significant decrease of MADRS scores occurred in patients treated with both drugs for 8 weeks. CONCLUSION: Atypical antipsychotic drugs may be particularly appropriate when treating schizophrenic patients with depression.

Adolescent↗
PubMed2005

P50 inhibitory gating deficit is correlated with the negative symptomatology of schizophrenia.

Abnormal sensory gating in schizophrenia has frequently been reported. The strength of central inhibitory pathways was measured using the P50 component of the auditory evoked potential in a conditioning-testing paradigm. The relationships between a relative decrease in P50 amplitude to repeated auditory stimuli and clinical symptoms remain controversial. Using the Positive and Negative Syndrome Scale, we studied the P50 auditory conditioning-testing paradigm in 81 schizophrenic subjects, categorized into subgroups with and without prominent negative symptoms, in comparison with 88 control subjects. We found increased ratios of testing stimuli to conditioning stimuli in both schizophrenic subgroups relative to findings in the control group. In addition, we found significantly increased mean latencies of the P50 responses to conditioning (C) and testing (T) stimuli and significantly increased T/C ratios in the subgroup with negative symptoms compared with the subgroup with non-negative symptoms.

Adult↗
PubMed2005

Atypical hemispheric specialization for language in right-handed schizophrenia patients.

BACKGROUND: The literature suggests that schizophrenia could be related to a failure in the setting up of left hemisphere dominance for language. We sought to determine hemispheric specialization for language in schizophrenic patients, using functional magnetic resonance imaging. METHODS: Twenty-one right-handed patients with DSM-IV schizophrenia and 21 right-handed control subjects matched by age, gender, and level of education were recruited. Fractional blood oxygen level dependent (BOLD) signal variations in anatomic regions of interest were compared between groups. Functional asymmetry indices (FAIs) were calculated in a region (LANG) resulting from the merging of activated regions showing a Group x Hemisphere interaction. The FAI difference between each patient and their matched control subject was computed. RESULTS: We found lower BOLD signal changes in patients as compared with their control subjects in a network comprising areas of the left middle temporal gyrus, the left angular gyrus, and the pars triangularis of the left inferior frontal gyrus, merged to constitute LANG. The intra-pair differences of FAIs in this area showed that 76% of the patients exhibited less leftward functional asymmetry than their matched control subjects, including six patients with a rightward asymmetry. CONCLUSIONS: These results demonstrated the existence of an anomaly in left hemisphere specialization for language in schizophrenic subjects.

Adult↗
PubMed2005

Impairments of executive/attentional functions in schizophrenia with primary and secondary negative symptoms.

Frontal cognitive inabilities have been amply described in schizophrenic patients with negative symptoms, but findings are controversial. These discrepancies could be due to the fact that negative symptoms are heterogeneous, composed of primary and secondary negative symptoms. The hypothesis tested was that executive/attentional dysfunctions would be significantly more impaired in patients with primary than in patients with secondary negative symptoms independently of IQ, the severity of negative or positive symptoms, treatments and side effects. Fifty-six DSM-IV schizophrenic patients characterized either by primary or secondary negative symptoms and 56 controls matched on age, sex and level of education were assessed with executive/attentional cognitive tests. The categories score of the Modified Card Sorting Test (MCST) and the Verbal Fluency Test, which reflect solving and organizing skills, were significantly more impaired in the primary negative subtype than in the secondary negative subtype. In contrast, scores on the MCST (perseveration), the Trail Making Test and the Stroop Color Word Test, which test the ability to inhibit an automatic response, did not differ between the two subtypes. In conclusion, this study supports the view that primary and secondary negative symptoms could be associated with different levels of executive/attentional dysfunctions.

Adolescent↗
PubMed2005

Hallucinogen persisting perception disorder after psilocybin consumption: a case study.

The recurrence of flashbacks without acute or chronic hallucinogen consumption has been recognized in the DSM IV criteria as the hallucinogen persisting perception disorder (HPPD). Perceptual disturbances may last for 5 years or more and represent a real psychosocial distress. We reported here a case of a 18-year-old young man presenting HPPD after a mixed intoxication with psylocibin and cannabis. This report shows symptomatic recurrences persisting more than 8 months. Various differential diagnoses were evoked and our therapeutic strategies were described.

Adolescent↗
PubMed2005

The subjective quality of life in deficit and nondeficit schizophrenic patients.

We assessed the subjective quality of life (QOL) of 30 deficit schizophrenic patients compared to 112 nondeficit schizophrenic patients. The deficit patients did not differ in term of QOL, total score of positive symptoms, general psychopathology from the nondeficit patients. This result suggested an absence of impact of primary negative symptoms on the subjective QOL in schizophrenic patients.

Adolescent↗
PubMed2005

A concordance study of three electrophysiological measures in schizophrenia.

OBJECTIVE: The authors evaluated concordance rates among three electrophysiological measures in patients with schizophrenia, nonschizophrenic first-degree relatives of schizophrenia patients, and healthy comparison subjects. The purpose of the study was to provide data for defining a common endophenotype for genetic studies of schizophrenia and for improving the criteria for diagnosis. METHOD: P50 event-related potential inhibition, antisaccade, and smooth pursuit eye tracking paradigms were measured. Data for all three paradigms were available for 81 patients with schizophrenia, 25 parents of patients with schizophrenia, and 60 healthy comparison subjects. RESULTS: The schizophrenia patients and the patients' parents showed a high rate of inhibitory deficits measured by the P50 inhibition and antisaccade paradigms. Both groups had a high prevalence of eye tracking dysfunction. Smooth pursuit gain and the error rate in the antisaccade paradigm were significantly correlated in the schizophrenia patients and the parents, whereas P50 inhibition showed no correlation with smooth pursuit gain or antisaccade paradigm measurements. CONCLUSIONS: Despite superficial similarities, two paradigms designed to measure central inhibition processes (antisaccade and P50 inhibition) do not appear to reflect the same neurobiological substrates. In contrast, the convergence in performance data for the antisaccade and eye tracking paradigms suggests that the neural circuitry underlying these tasks may overlap. P50 inhibition and antisaccade errors were the optimal paradigms for discrimination between comparison subjects, patients with schizophrenia, and the parents of patients with schizophrenia.

Adult↗
PubMed2004

Relationship between performance on the Stroop test and N-acetylaspartate in the medial prefrontal cortex in deficit and nondeficit schizophrenia: preliminary results.

The aim of this research was to investigate the relationship between performance on the Stroop test and N-acetylaspartate/creatine assessed using proton magnetic resonance spectroscopy in the medial prefrontal cortex (MPFC) of schizophrenia patients. The Schedule for the Deficit Syndrome was used to subdivide the schizophrenia patients into deficit (n=5) and nondeficit (n=17) subtypes. Twenty-one control subjects served as a comparison group. A strong correlation between right-sided N-acetylaspartate/creatine levels and Stroop scores was found in the deficit patients but not in the nondeficit patients and the controls. This result suggests a relationship between a dysfunction of the right medial prefrontal cortex and a deficit in selective attention in schizophrenia patients with the deficit syndrome.

Aspartic Acid↗
PubMed2004

Summer birth and deficit schizophrenia: a pooled analysis from 6 countries.

BACKGROUND: In some reports, summer birth has been associated with deficit schizophrenia. Deficit schizophrenia and nondeficit schizophrenia also differ in several other ways. OBJECTIVE: To conduct a combined analysis of the published and unpublished data sets from the northern hemisphere that relate deficit and nondeficit schizophrenia to month of birth. DATA SOURCES: Studies of season of birth in which it was possible to make a deficit/nondeficit categorization. STUDY SELECTION: Published studies with samples of convenience and all known population-based studies with the deficit/nondeficit categorization were included. The studies came from 6 countries. DATA EXTRACTION: Three published studies of samples of convenience, 2 population-based prevalence studies, and 5 population-based studies that approximated incident samples were included. Month of birth was compared for deficit and nondeficit schizophrenia, using meta-analytic fixed-effects models. DATA SYNTHESIS: A group x month goodness-of-fit chi2 showed a significant difference between deficit and nondeficit subjects in season of birth (P < .001) in the studies that approximated incidence. This difference was largely due to an increase in deficit schizophrenia births in June and July (odds ratio, 1.9; 95% confidence interval, 1.3-2.9). Similar results were found in the prevalence studies. A similar pattern was found in 2 of the 3 samples of convenience, but when combined, these 3 samples did not show a significant deficit/nondeficit difference. CONCLUSIONS: Deficit schizophrenia has a season of birth pattern that differs from that of nondeficit schizophrenia. This analysis supports the notion of a separate disease within schizophrenia.

Cohort Studies↗
PubMed2003

Verbal learning and memory in schizophrenic and Parkinson's disease patients.

The purpose of this study was to investigate the neurofunctional substrate of verbal learning and memory impairments in schizophrenic patients. In this pilot study, our aim was to compare the memory disturbance of schizophrenic patients to the subcortico-frontal memory profile of Parkinson's disease (PD) patients. The California Verbal Learning Test, a verbal episodic memory test, was administered to 60 subjects, 20 patients with schizophrenia, 20 patients with PD and 20 healthy control subjects. All subjects were aged between 50 and 70 years and all patients were in a stable phase. Like the Parkinson patients, the schizophrenic patients showed a major deficit of retrieval characterized by deficit of recalls but contrarily to PD patients, schizophrenic patients' encoding scores were altered. These impairments in episodic memory could suggest a dysfunction of the subcortico-frontal circuits in schizophrenic patients. However, they demonstrated an additional encoding deficit associated with probable frontal in situ alteration.

Aged↗
PubMed2002

Sinistrality in schizophrenia.

UNLABELLED: Sinistrality characterized by an excess of non-right handedness has been reported in schizophrenic patients. Two factors, sex and kind of evaluation of handedness have contributed to major discrepancies across studies. AIM: The hypothesis tested was that schizophrenic patients show a sinistral shift in handedness compared to controls taking into account the sex and using a continuum scoring system for evaluating handedness. METHODS: Seventy-three (73.1% males) schizophrenic patients (DSMIV) and 81 (64.2% males) controls were evaluated with the Edinburgh Handedness Inventory (EHI [Neuropsychologia, 9 (1971) 97]). RESULTS: The EHI score mean difference between patients with schizophrenia and control group was not significant when sex was taken into account. CONCLUSION: Schizophrenic patients taken as a whole did not show a sinistral shift in handedness even if the sex and the continuum score for handedness were considered.

Adult↗
PubMed2002

Executive/attentional cognitive functions in schizophrenic patients and their parents: a preliminary study.

The aim of this study was to determine whether executive/attentional cognitive performances could be considered as markers of vulnerability to schizophrenia. The Stroop Color Word and fluency tests were significantly impaired in schizophrenic patients and their parents compared to controls matched on age and sex while performances on Nelson's Modified Card Sorting Test and the Trail Making Test did not differ. The impairments on the Stroop and fluency could be considered as endophenotypic markers of schizophrenia.

Adult↗
PubMed2002

Sinistrality in subtypes of schizophrenia.

UNLABELLED: Sinistrality, characterized by an excess of non-right-handedness, has been reported in schizophrenic patients, but the findings are controversial. AIM: As sinistrality could be linked to a failure of hemisphere specialization in schizophrenia that would translate into language disorders, sinistrality was found out in disorganized and positive schizophrenic patients characterized by language disorders. METHODS: Seventy-three schizophrenic patients (DSM IV) and 81 controls were evaluated with the Edinburgh Handedness Inventory (EHI). Patients were evaluated and classified into five subtypes (deficit, positive, disorganized, mixed and residual) with the Positive and Negative Syndrome Scale and the Schedule for the Deficit Syndrome. RESULTS: Disorganized patients had a significantly more severe sinistrality in comparison to the deficit, residual and mixed subtypes and controls. A negative correlation was found between the disorganization and the EHI scores (r = - 0.34; P < 0.01). A significantly more severe sinistrality was also observed in the positive subtype in comparison to controls, but there was no correlation between hallucinatory and EHI scores (r = 0.06). CONCLUSION: The findings provided further evidence that the defects in the normal process of lateralization observed in schizophrenia affects primarily disorganized patients.

Adult↗
PubMed2002

Proton magnetic resonance spectroscopy (1H MRS) in schizophrenia: investigation of the right and left hippocampus, thalamus, and prefrontal cortex.

Single voxel proton magnetic resonance spectroscopy (1H MRS) was used to study the metabolites N-acetylaspartate (NAA), choline (CHO), and myo-inositol (ml) in order to test a neurodegenerative hypothesis in schizophrenia (decrease of NAA, increase of CHO, and increase of ml) and a cerebral asymmetry of these metabolites. 1H MRS was performed in 17 schizophrenia patients and 14 healthy subjects in three cerebral areas highly involved in the pathophysiology of schizophrenia (the prefrontal cortex, the thalamus, and the hippocampus). The ratio amplitudes between metabolites and creatine plus phosphocreatine (Cr) were determined. No difference in the metabolites existed between patients and healthy subjects. However, relationships were noted between NAA/Cr and age in the thalami of the schizophrenia patients (r = -0.37; p = 0.14) and healthy subjects (r = -0.52; p = 0.05). A significant correlation was observed between NAA/Cr and age of onset of illness in the hippocampi of schizophrenia patients (r = -0.59; p < 0.05). Moreover, NAA/Cr was lower in the right than in the left prefrontal cortex in both schizophrenia patients and healthy subjects. There was no relationship between the metabolites and duration of illness or dose of antipsychotics. These findings might suggest a neurodegenerative process in the hippocampi of schizophrenia patients with late onset of illness, and the NAA/Cr ratio could be a marker of aging in the thalami.

Adult↗