Karim Tabbane

Self-perceived cognitive functioning does not correlate with objective measures of cognition in schizophrenia

BACKGROUND Growing interest in the study of self-perceived cognitive deficits in schizophrenia has been recently observed. The authors validated in a previous study the Subjective Scale To Investigate Cognition into Schizophrenia Tunisian Arabic Version (SSTICS_tun_arab), a self-questionnaire established to collect cognitive complaints in patients with schizophrenia. OBJECTIVE The aim of the present study was to explore the relationship between the SSTICS_tun_arab scores and objective cognitive performances. METHODS One hundred four patients with schizophrenia spectrum disorders were administered measures of the Positive and Negative Syndrome Scale, the Global Assessment Functioning Scale, and the Calgary Depression Scale as well as measures of the SSTICS_tun_arab and a cognitive battery. RESULTS No correlations were found between objective neuropsychologic performances and scores of the SSTICS_tun_arab. CONCLUSIONS Our findings support the hypothesis of independence of self-perceived cognitive functioning from objective neuropsychologic deficits in schizophrenia. They also suggest that insight of mental illness seems to be not a unitary concept but more likely to be divided in different aspects including cognitive insight.

No association between the DRD3 Ser9Gly polymorphism and schizophrenia.

OBJECTIVE To investigate the association between a Ser9Gly polymorphism of the dopamine D3 receptor gene (DRD3) and schizophrenia. METHODS 408 schizophrenic patients and 172 control subjects were compared with regard to their DRD3 Ser9Gly genotypic and allelic frequencies. In addition, we carried out a family-based association study including 183 pedigrees (472 subjects) using the transmission disequilibrium test (TDT). RESULTS No significant differences of genotype or homozygosity distribution were identified between patients and controls. When patients were stratified according to gender, response to treatment, age at onset, no significant differences were observed. Neither allele A (Ser), or G (Gly) were preferentially transmitted from parents to affected offspring. CONCLUSION The hypothesis that the DRD3 Ser9Gly polymorphism plays a predisposing role in schizophrenia is not supported by this study.

Confirmation for a delayed inhibition of return by systematic sampling in schizophrenia.

Inhibition of return (IOR) is a phenomenon thought to reflect a mechanism to protect the organism from redirecting attention to previously scanned insignificant locations. A number of studies reported altered IOR in schizophrenia patients with a reduction of its amplitude. However, incomplete sampling of stimulus onset asynchronies (SOAs) makes data on IOR time course incomplete. We examined 14 stabilized young patients with recent onset schizophrenia and 16 healthy controls matched for gender, age, and years of education. Schizophrenia patients (13 males, 1 female) had a mean age of 26.3+/-5.8 years and a mean number of years of study of 9.6+/-3.6. Their illness had a mean duration of 147 weeks. Patients displayed moderate overall slow reaction times (387 ms) in comparison with controls (322 ms). Onset of IOR was found to be delayed in schizophrenia patients appearing between 700 and 800 ms following the cue onset while it appeared at 300 ms in controls. In patients, IOR was constant up to 1100 ms; however, its amplitude was weak with an average of 6 ms. Validity effects (overall and at each SOA value) were uncorrelated to age, years of study, duration of illness, or total or subscale scores on the Positive and Negative Syndrome Scale.

Association study of the trinucleotide repeat polymorphism within SMARCA2 and schizophrenia.

BackgroundBrahma (BRM) is a key component of the multisubunit SWI/SNF complex, a complex which uses the energy of ATP hydrolysis to remodel chromatin. BRM contains an N-terminal polyglutamine domain, encoded by a polymorphic trinucleotide (CAA/CAG) repeat, the only known polymorphism in the coding region of the gene (SMARCA2). We have examined the association of this polymorphism with schizophrenia in a family-based and case/control study. SMARCA2 was chosen as a candidate gene because of its specific role in developmental pathways, its high expression level in the brain and some evidence of its association with schizophrenia spectrum disorder from genome-wide linkage analysis.ResultsFamily-based analysis with 281 complete and incomplete triads showed that there is no significant preferential transmission of any of the alleles to the affected offspring. Also, in the case/control analysis, similar allele and genotype distributions were observed between affected cases (n = 289) and unaffected controls (n = 273) in each of three Caucasian populations studied: French Canadian, Tunisian and other Caucasians of European origin.ConclusionResults from our family-based and case-control association study suggest that there is no association between the trinucleotide repeat polymorphism within SMARCA2 and schizophrenia.

Le phénomène de l’inhibition de retour dans la schizophrénie : revue de la littérature

INTRODUCTION Most visual environments contain more information than the human brain can process in real time. To overcome this limitation, the attention system acts as a filter by selectively orienting attention to specific regions of the visual field. This ability to orient attention can be reflected in covert shift processes of attention. LITERATURE FINDINGS In a typical covert orienting task, subjects have to maintain fixation on a central cross and respond as quickly as possible to a target, which appears in a peripheral box following a cue that summons attention to the direction where the target is going to appear (valid cueing) or to the contralateral direction (invalid cueing). When the cues are nonpredictive, the response characteristics critically depend on stimulus-onset asynchrony (SOA). With short SOAs (<300ms), valid cues result in a reaction time advantage over invalid trials, which is due to a reflexive shift of attention towards the source of stimulation. In contrast, with longer SOAs, valid cues result in longer reaction times to the subsequent target. DISCUSSION This phenomenon is known as the inhibition of return and is mostly thought to reflect an inhibitory mechanism protecting the organism from redirecting attention to previously scanned insignificant locations. Many studies have reported blunted or delayed inhibition of return in patients with schizophrenia. However, some authors reported normal amounts of inhibition of return. This can be partly explained by the use of manipulations of the covert orienting of the attention paradigm that is known to enhance the course of inhibition of return. CONCLUSION The deficit of inhibition of return seems to be time-stable and to be unrelated to psychopathology or length of illness. The contribution of neuroleptic medication to this deficit cannot be determined. Recent data suggest a deficit of inhibition of return in two human models of psychosis (dimethyltryptamine and ketamine). Further studies should clarify whether blunted inhibition of return might represent a trait marker of schizophrenia.

Theory of mind in adolescents with early-onset schizophrenia: correlations with clinical assessment and executive functions

Objective We examined Theory of Mind (ToM) abilities in adolescents with early-onset schizophrenia (EOS) and their correlation with clinical findings and Executive Functions (EF). Methods The ToM abilities of 12 adolescents with EOS were compared with those of healthy participants matched in age and educational level. The Moving Shapes Paradigm was used to explore ToM abilities in three modalities: random movement, goal-directed movement and ToM – scored on the dimensions of intentionality, appropriateness and length of each answer. EF was tested using Davidson’s Battery and the clinical psychopathology with the Positive and Negative Syndrome Scale (PANSS). Results Adolescents with EOS were significantly more impaired than controls in the three dimensions evaluated for the goal-directed and ToM modalities. Regarding the random movement modality, the only difference was in appropriateness (p<0.01). No correlation with age or level of education was evident for ToM skills. Total PANSS score was negatively correlated with appropriateness score for the goal-directed (p=0.02) and ToM modalities (p=0.01). No correlation existed between performance in the ToM Animated Tasks and positive, negative or disorganisation PANSS subscores. No correlations were found among the three scores in the Moving Shapes Paradigm and any measures of the accuracy of the three tasks assessing EF. Conclusion Our results confirm previous findings of ToM deficits in adult individuals with schizophrenia and attest the severity of these deficits in patients with EOS.

Generalizing Duchenne to Sad Expressions with Binocular Rivalry and Perception Ratings

Discrete emotion theories emphasize the modularity of facial expressions, while functionalist theories suggest that a single facial action may have a common meaning across expressions. Smiles involving the Duchenne marker, eye constriction causing crow’s feet, are perceived as intensely positive and sincere. To test whether the Duchenne marker is a general index of intensity and sincerity, we contrasted positive and negative expressions with and without the Duchenne marker in a binocular rivalry paradigm. Both smiles and sad expressions involving the Duchenne marker were perceived longer than non-Duchenne expressions, and participants rated all Duchenne expressions as more affectively intense and more sincere than their non-Duchenne counterparts. Correlations between perceptual dominance and ratings suggested that the Duchenne marker increased the dominance of smiles and sad expressions by increasing their perceived affective intensity. The results provide evidence in favor of Darwin’s hypothesis that specific facial actions have a general function (conveying affect intensification and sincerity) across expressions.

Emotion Perception is Valence-Dependent during Binocular Rivalry.

The perceptual strength of a facial expression is widely shaped by context. Binocular rivalry (BR) has proven to be a promising tool in studying face perception. It involves the alternation between two stimuli that are simultaneously, but monocularly, presented. BR is postulated to occur due to inhibitory interactions between neuronal populations tuned for the presented stimuli. Therefore, BR provides a reflection of perceptual strength, whereby shorter stimulus perception (dominance duration) signifies greater inhibition and weaker tuning. We previously demonstrated that, while there may be an interaction between the identity and emotion portrayed by face stimuli during BR, emotion has a stronger influence and thus holds greater perceptual strength. Moreover, positive emotions tend to dominate over negative ones. To assess whether perceptual strength is also dependent on the intensity of an emotion (valence), 3D natural-looking face identities of similar skin tone and gender were created in FaceGen Modeller to express five emotions (very happy, happy, neutral, sad, and very sad) and were set to rival as 29 human subjects reported which stimulus they perceived throughout a trial. Prior BR studies that investigated valence-dependence were confounded by stimuli discrepancies that highlight certain local facial features over others. Here, extreme emotions were portrayed through the use of Duchenne eye constrictions, which permitted control over feature-salience across stimuli. Subjects reported that extreme emotions were perceived for significantly greater dominance durations than basic ones (p < 7.91x10-7, Kolmogorov-Smirnov [KS]). Furthermore, when the same stimuli were inverted and rivaled, all dominance durations were rendered insignificantly different from one another (p > 0.11, KS). This verifies that the observed significance using Duchenne characteristics was not driven by the local feature-eye wrinkles, but rather by the global emotion portrayed. Overall, the more intense an emotion, the greater its perceptual strength and possibly the higher its processing priority during BR. Meeting abstract presented at VSS 2015.