Showing papers by "Marie-Odile Krebs published in 2001"

Is substance abuse in schizophrenia related to impulsivity, sensation seeking, or anhedonia?

Abstract: OBJECTIVE: The authors compared impulsivity, sensation seeking, and anhedonia in a group of schizophrenic patients with and without lifetime substance abuse or dependence. METHOD: Patients (N=100) with schizophrenia or schizoaffective disorder (per DSM-III-R criteria) were assessed with the Composite International Diagnostic Interview’s section on psychoactive substance use disorder, the Positive and Negative Syndrome Scale, the Barratt Impulsivity Scale, the Zuckerman Seeking Sensation Scale, and the Chapman Physical Anhedonia Scale. RESULTS: The mean scores for impulsivity and sensation seeking were higher in the group with substance abuse (N=41) than in the group without substance abuse (N=59). No significant difference between groups was found regarding physical anhedonia. CONCLUSIONS: As in the general population, high levels of impulsivity and sensation seeking are associated with substance abuse in patients with schizophrenia.

Substance abuse and suicidality in schizophrenia: a common risk factor linked to impulsivity.

Abstract: Lifetime substance abuse comorbidity is frequent in schizophrenic patients, but the clinical correlates remain unclear. We have explored the chronological relations between substance abuse and course of schizophrenia, and compared several clinical characteristics and personality dimensions in 50 schizophrenic patients with or without lifetime substance abuse or dependence. Abuse occurred mainly after the first prodromal symptoms and just before the first psychotic episode. Substance-abusing patients were not different from non-substance-abusing patients on the Chapman Physical Anhedonia Scale, PANSS total score, negative subscore or depression item, CGI, treatment response and demographic variables. In contrast, substance-abusing patients had higher scores on the Barratt Impulsivity Scale (total, cognitive and non-planning scores) and had attempted suicide more often. In patients with schizophrenia, as in the general population, substance abuse or dependence appears associated with higher impulsivity and suicidality. High impulsivity could facilitate substance abuse as a maladaptive behavior in response to prodromal symptoms, precipitating the onset of a characterized psychosis.

Schizophrenia and the cannabinoid receptor type 1 (CB1): association study using a single-base polymorphism in coding exon 1.

Abstract: Abuse of cannabis is frequent among the young and is suspected to precipitate schizophrenia in vulnerable subjects. Cannabinoid receptor (CB1) is particularly concentrated in dopamine-modulated areas of the nervous system. An association between an AAT polymorphism of the CB1 gene and intravenous drug abuse has been previously reported, but not with schizophrenia. In a French Caucasian population, we compared the distribution of a single-base polymorphism revealed by MspI within the first exon of the CB1 gene in patients with schizophrenia (n = 102) and ethnic- and gender-matched controls (n = 63). No significant difference was seen in the allele or genotype distribution between the whole sample of schizophrenic patients and controls. However, we found a borderline lack of allele g and a significant lack of gg genotype in the non-substance-abusing patients compared to substance-abusing patients, the latter being similar to the controls. These results are the first report of an significant association between CB1 receptor and a subtype of schizophrenia. Studies are needed to confirm and further explore the precise role of the cannabinoid system in schizophrenia.

Impairment of predictive saccades in schizophrenia.

Abstract: Using infrared oculography, we compared saccades toward predictable and pseudo-random visual targets in 19 neuroleptic-free patients with schizophrenia (including 13 neuroleptic-naive patients) and in 29 age- and gender-matched healthy volunteers. Externally driven saccades were not different between patients and controls, whether or not the target was predictable. Anticipated saccades were specifically less accurate in the patients compared to the controls. The difference between primary gain of anticipated and non-anticipated saccades was markedly higher in the patients compared to controls (p=0.003). These results point to a deficit in the early step of internally driven oculomotor planning in schizophrenia.

French validation of a Minor Morphologic Anomalies Scale in schizophrenic patients and their parents

Abstract: UNLABELLED Minor Physical Anomalies represent valuable indices of disturbance in early neurodevelopment. They are frequently observed in individuals with various brain disorders, including mental retardation, autism, epilepsy, hyperactivity, foetal alcohol syndrome and schizophrenia. The high prevalence of Minor Physical Anomalies in schizophrenia provides considerable support for a neurodevelopmental model in this disorder. However, studies in large sample using standardised scale are lacking. Such studies are needed in order to confirm their actual frequency and study the clinical correlates or morphological anomalies. OBJECTIVE The aim of this study was to revise and validate a French version of a scale designed for the evaluation of Minor Physical Anomalies in adult psychiatric patients and notably in patients with schizophrenia. METHODOLOGY The scale was revised from the Waldrop scale. The choice of items was done on the basis of frequency, reliability in the adult, reliability of rating. Some new items, related to know syndroms with comportmental symptoms were added. Both raters had previously had a short initiation to the rating of the scale. Interrater reliability between two examiners, blind with regards to the diagnosis was evaluated. RESULTS The interrater reliability was good, with an intraclass correlation coefficient at 0.97. Patients had significantly more minor physical anomalies than comparison subjects, and also more Minor Physical Anomalies than their parents. Fathers and mothers of these schizophrenic patients had significantly more Minor Physical Anomalies than normal comparison subjects. CONCLUSION Although the evaluation of physical anomalies relies on subjective appreciation of normal vs abnormal, the revised version of minor physical anomalies scale (French version) was found to be a reliable tool, provided that a short initiation to the rating is performed. The scale differentiated schizophrenic patients from their parents, and the latter from the normal controls. A lot of questions remains unanswered concerning the neurodevelopmental hypothesis of schizophrenia. This scale appeared as a useful complementary tool to help in the determination of the developmental phenotypic status of the patients enrolled in pathophysiological studies aiming the identification of developmental factors in schizophrenia.

Measure and analysis of a gaze position using infrared light technique

Abstract: We are interested in identifying the object or area that attracts the subject's attention in images. A computer system is developed to measure and analyze the eye position. Eye movements are recorded using an infrared light device. Our interest is concentrated mainly on the calibration of the system, more precisely, on the correction of measured data according to user's characteristics. Higher polynomial transformation is used to model the mapping between eye coordinates and image coordinates. The mean quadratic error criteria is used. This paper presents how our model works to correct the non-linearities in the oculomotor system for individual subject's eyes. It also proposes a method to correct head movements.