Julie Palix

Comparison of Early Cortical Networks in Efficient and Inefficient Visual Search: An Event-Related Potential Study

Functional magnetic resonance imaging studies have indicated that efficient feature search (FS) and inefficient conjunction search (CS) activate partially distinct frontoparietal cortical networks. However, it remains a matter of debate whether the differences in these networks reflect differences in the early processing during FS and CS. In addition, the relationship between the differences in the networks and spatial shifts of attention also remains unknown. We examined these issues by applying a spatio-temporal analysis method to high-resolution visual event-related potentials (ERPs) and investigated how spatio-temporal activation patterns differ for FS and CS tasks. Within the first 450 msec after stimulus onset, scalp potential distributions (ERP maps) revealed 7 different electric field configurations for each search task. Configuration changes occurred simultaneously in the two tasks, suggesting that contributing processes were not significantly delayed in one task compared to the other. Despite this high spatial and temporal correlation, two ERP maps (120190 and 250300 msec) differed between the FS and CS. Lateralized distributions were observed only in the ERP map at 250300 msec for the FS. This distribution corresponds to that previously described as the N2pc component (a negativity in the time range of the N2 complex over posterior electrodes of the hemisphere contralateral to the target hemifield), which has been associated with the focusing of attention onto potential target items in the search display. Thus, our results indicate that the cortical networks involved in feature and conjunction searching partially differ as early as 120 msec after stimulus onset and that the differences between the networks employed during the early stages of FS and CS are not necessarily caused by spatial attention shifts.

Validity and Predictive Accuracy of the Structured Assessment of Protective Factors for Violence Risk in Criminal Forensic Evaluations: A Swiss Cross-Validation Retrospective Study

Some actuarial and structured professional judgment (SPJ) risk-assessment instruments have already demonstrated their validity and predictive accuracy in expert criminal forensic evaluations. In contrast, little is known about the effectiveness of instruments identifying protective factors in risk of recidivism prediction. The present study was designed to evaluate the validity and predictive accuracy of the Structured Assessment of Protective Factors for Violence Risk (SAPROF) in 94 violent and sexual violent offenders assessed in a Swiss pretrial criminal forensic context. The SAPROF showed good interrater reliability, and was significantly correlated to predominately dynamic instruments but not to predominately actuarial instruments. However, in terms of predictive accuracy, the SAPROF did not perform as well as expected when compared with other instruments and with previous SAPROF accuracy validation studies. These results have implications for the use of the SAPROF in criminal forensic contexts risk assessment.

Visuo-Spatial Attention Frame Recognition for Brain-Computer Interfaces

Objective: To assess the feasibility of recognizing visual spatial attention frames for Brain-computer interfaces (BCI) applications. Methods: EEG data was recorded with 64 electrodes from 2 subjects executing a visual spatial attention task indicating 2 target locations. Continuous Morlet wavelet coefficients were estimated on 18 frequency components and 16 preselected electrodes in trials of 600 ms. The spatial patterns of the 16 frequency components frames were simultaneously detected and classified (between the two targets). The classification accuracy was assessed using 20-fold crossvalidation. Results: The maximum frames average classification accuracies are 80.64% and 87.31% for subject 1 and 2 respectively, both utilizing coefficients estimated at frequencies located in gamma band.

Insight et comportements violents dans une cohorte de patients souffrant de premiers épisodes de psychose

Objectives: An important proportion of patients with first episode psychosis behave in a violent, hetero-aggressive manner. This study aims to explore the association between insight and violent behavior (VB), and insight evolution in the follow-up period. Method: The study was carried out with a prospective cohort of 265 patients recruited from the early treatment and intervention for psychotic disorders program, and followed for a 3-year period. Insight assessing is based on a 3-item scale and the insight item in Positive and Negative Syndrome Scale (PANSS). VBs were evaluated by case managers, information from forensic services and through a record of VBs noted during hospitalization. Univariate and multivariate logistic regression analyses, t-tests and correlations were conducted. Results: The significant effect of insight as a factor associated with VBs that was found in univariate analyses disappears after controlling for the effect of positive symptoms, substance addiction diagnosis, impulsivity and treatment compliance. Conclusion: If patient insight in their illness develops positively during treatment, our results suggest that the risk of VBs occurring is not influenced by insight level. On the other hand, it is significantly linked to substance abuse and impulsivity, which might implicate focusing on these 2 dimensions in preventive strategies. Insight impact on VB should be further explored in more focused prospective analyses.Objectifs: Une proportion importante de patients présentant un premier épisode psychotique commettent des actes violents hétéro-agressifs. L’objectif de cette étude est d’explorer l’association entre insight et comportement violent (CV) et l’évolution de l’insight durant la période de suivi. Méthode: L’étude est conduite sur une cohorte prospective de 265 patients recrutés au sein du programme de traitement et d’intervention précoce dans les troubles psychotiques et suivis sur une période de 3 ans. L’évaluation de l’insight est basée sur une échelle d’insight en 3 points et l’item de l’insight à la Positive and Negative Syndrome Scale (PANSS). Les CV ont été évalués par les case-managers, par les informations provenant des services forensiques et par l’intermédiaire d’un relevé des CV en cours d’hospitalisation. Des analyses de régression logistique uni-variées et multi-variées, des tests-t et des corrélations ont été réalisés. Résultats: L’effet significatif de l’insight comme facteur associé aux CV trouvé dans les analyses uni-variées disparaît après avoir contrôlé l’effet des symptômes positifs, du diagnostic de dépendance aux substances, de l’impulsivité et de l’adhésion au traitement. Conclusion: Si la prise de conscience des patients à l’égard de leur maladie évolue positivement au cours du traitement, nos résultats suggèrent que le risque de survenue de CV n’est pas influencé par le degré d’insight. Il est par contre significativement lié à l’abus de substances et à l’impulsivité, impliquant de cibler ces deux dimensions dans les stratégies préventives. L’impact de l’insight sur le CV doit être l’objet d’analyses prospectives plus précises.

Impulsivity in early psychosis: A complex link with violent behaviour and a target for intervention

BACKGROUND Violent behaviour (VB) occurs in first episode of schizophrenia and can have devastating impact both on victims and patients themselves. A better knowledge of the underlying mechanisms of VB may pave the way to preventive treatments. OBJECTIVES 1) To explore the nature of the link between impulsivity and VB in early psychosis (EP) patients; 2) To explore the interactions between impulsivity and substance abuse, insight, and positive symptoms, the main dynamic risk factors of VB described to date. DESIGN AND METHODS Post hoc analysis of data acquired in the frame of a 36-months EP cohort study. A total of 265 EP patients, aged 18 to 35, treated at TIPP (Treatment and early Intervention in Psychosis Program), at the Department of Psychiatry in Lausanne, Switzerland, were included in the study. Logistic regression analyzes were performed as well as mediation analysis and interaction analysis RESULTS: Our data suggest that impulsivity is a predictor of VB when analyzed independently and as part of a multi-factorial model. Impulsivity continues to differentiate violent patients from non-violent ones at the end of the program. In addition, the relationship between impulsivity and VB is not mediated by substance abuse. Finally, the effect of impulsivity on the probability of VB is potentiated by the interaction of different levels of insight and positive symptoms. CONCLUSIONS Early intervention strategies in psychotic disorders should include evaluation of impulsivity considering it is linked to increased risk of VB and may respond to treatment.

Violent behaviour in early psychosis patients: Can we identify clinical risk profiles?

The objective of this study is to explore, within a sample of early psychosis patients (EPP), if subgroups regarding rate of violent behaviour (VB) against others can be identified on the basis of dynamic risk factors (treatment modifiable characteristics).

Changes in Heart Rate Variability Recorded in Natural Situation with T-Shirt Integrated Sensors and Level of Observed Behavioral Excitation: A Pilot Study of Patients with Intellectual Disabilities and Psychiatric Disorders

Background The present study investigates the possibilities of using heart rate variability (HRV) parameters as physiological markers that precede increase in observed behavioral excitation of intellectually disabled individuals. The ability to recognize or predict such patterns, especially in patients showing unpredictable reactions and language deficiencies, might be a major step forward in clinical research. Method Thirteen volunteers with intellectual disabilities, who had suffered of at least one event of overt aggression in the preceding 3 months, participated to the study. The protocol consists in the acquisition of continuous electrocardiogram (ECG) throughout approximately two times of 8 h in natural situation, using a T-shirt integrated with sensors. Simultaneously, an observer evaluates the patient’s level of overt excitation from calm (level 1) to extremely tense (level 5) and send online via Bluetooth these triggers into the ECG signals. The HRV indexes were then estimated offline on the basis of the inter-beat intervals recorded by the ECG, independently for the 30 min preceding each behavioral tension marking point, averaged, and compared through non-parametric Wilcoxon matched-pairs test. Of these, the RMSSD and LF/HF calculations were used to observe the fluctuations of inhibitory activity and cardiovagal balance through different tension states. Results Seven individuals have sufficient reliable data for analysis. They have reached at least a level 3 of behavioral excitation (moderately tense) or more (very to extremely tense, level 4 and 5) and have been retained for further analysis. In sum, a total of 197 periods of tension were kept, made up of 46 periods of slight excitation (level 2), 18 of moderate excitation (level 3), 10 of high excitation (level 4), and 5 of extreme agitation (level 5). Variations in the HRV as a function of degree of excitation are observed for RMSSD index only (inhibitory parasympathetic activity). The changes from calm to increasing levels of excitation are characterized by a significant downfall in RMSSD index when patients were evaluated to be in a very high level of tension (level 4). Conclusion The presence of precursors to agitation, reflected in the falling-off of parasympathetic activity, offers potentially interesting prospects for therapeutic development.

Cannabis, a Significant Risk Factor for Violent Behavior in the Early Phase Psychosis. Two Patterns of Interaction of Factors Increase the Risk of Violent Behavior: Cannabis Use Disorder and Impulsivity; Cannabis Use Disorder, Lack of Insight and Treatment Adherence

Background: Previous literature suggests that prevalence of cannabis use in the early phase of psychosis is high, and that early psychosis patients are at high-risk for violent behavior. However, the link between cannabis use and violent behavior in early psychosis patients is unclear. We carried out a study on a sample of early psychosis patients, in order to explore the impact of cannabis use on the risk of violent behavior (VB), while taking into account (1) potential confounding factors and, (2) interactions with other dynamic risk factors of VB. Method: In a sample of 265 early psychosis patients, treated at the Treatment and Early Intervention in Psychosis Program (TIPP) in Lausanne, we used logistic regression models to explore the link between various dynamic risk factors of VB [positive symptoms, substance use disorder (drugs including cannabis, alcohol and others drugs), insight, impulsivity, affective instability, and treatment adherence], and VB occurring during treatment. In order to understand hierarchical effects attributable to the combinations of risk factors on VB we conducted a Classification and Regression Tree (CART). Results: Our results show that cannabis use disorder is a risk factor for VB. The associations among risk factors suggest the presence of two patient profiles with an increased rate of VB: the first is composed of patients with cannabis use disorder and impulsivity, and the second of patients combining cannabis use disorder, absence of insight and non-adherence to treatment. The results also show the moderating role of insight and adherence to treatment on the rate of VB in patients with cannabis use disorder. Conclusion: This study suggests that cannabis use disorder is a significant risk factor for VB amongst early psychosis patients, particularly when combined with either impulsivity, lack of insight and non-adherence to treatment. These results suggest that preventive strategies could be developed on the basis of such patient profiles.

Frontal cortical thickness correlates positively with impulsivity in early psychosis male patients

Impulsive behaviours, which are frequent in young people suffering from psychosis have been linked to risky and violent behaviours and participate to the burden of psychotic illness. Given that morphological brain correlates of impulsivity in schizophrenia have been poorly investigated especially in young adults, the aim of this study was to investigate the relationship between impulsivity and cortical thickness in early psychosis (EP) patients.