Daniela Herzig

Cognitive disorganisation in schizotypy is associated with deterioration in visual backward masking

To understand the causes of schizophrenia, a search for stable markers (endophenotypes) is ongoing. In previous years, we have shown that the shine-through visual backward masking paradigm meets the most important characteristics of an endophenotype. Here, we tested masking performance differences between healthy students with low and high schizotypy scores as determined by the self-report O-Life questionnaire assessing schizotypy along three dimensions, i.e. positive schizotypy (unusual experiences), cognitive disorganisation, and negative schizotypy (introvertive anhedonia). Forty participants performed the shine-through backward masking task and a classical cognitive test, the Wisconsin Card Sorting Task (WCST). We found that visual backward masking was impaired for students scoring high as compared to low on the cognitive disorganisation dimension, whereas the positive and negative schizotypy dimensions showed no link to masking performance. We also found group differences for students scoring high and low on the cognitive disorganisation factor for the WCST. These findings indicate that the shine-through paradigm is sensitive to differences in schizotypy which are closely linked with the pathological expression in schizophrenia.

The influence of tobacco consumption on the relationship between schizotypy and hemispheric asymmetry

Tobacco use is positively associated with severity of symptoms along the schizophrenia spectrum. Accordingly it could be argued that neuropsychological performance, formerly thought to be modulated by schizotypy, is actually modulated by drug use or an interaction of drug use and schizotypy. We tested whether habitual cigarette smokers as compared to non-smokers would show a neuropsychological profile similar to that observed along the schizophrenia spectrum and, if so, whether smoking status or nicotine dependence would be more significant modulators of behavior than schizotypy. Because hemispheric dominance has been found to be attenuated along the schizophrenia spectrum, 40 right-handed male students (20 non-smokers) performed lateralized left- (lexical decisions) and right- (facial decision task) hemisphere dominant tasks. All individuals completed self-report measures of schizotypy and nicotine dependence. Schizotypy predicted laterality in addition to smoking status: While positive schizotypy (Unusual Experiences) was unrelated to hemispheric performance, Cognitive Disorganization predicted reduced left hemisphere dominant language functions. These latter findings suggest that Cognitive Disorganization should be regarded separately as a potentially important mediator of thought disorganization and language processing. Additionally, increasing nicotine dependence among smokers predicted a right hemisphere shift of function in both tasks that supports the role of the right hemisphere in compulsive/impulsive behavior.

The trail making test as a screening instrument for driving performance in older drivers; a translational research

BackgroundIn many countries, primary care physicians determine whether or not older drivers are fit to drive. Little, however, is known regarding the effects of cognitive decline on driving performance and the means to detect it. This study explores to what extent the trail making test (TMT) can provide indications to clinicians about their older patients’ on-road driving performance in the context of cognitive decline.MethodsThis translational study was nested within a cohort study and an exploratory psychophysics study. The target population of interest was constituted of older drivers in the absence of important cognitive or physical disorders. We therefore recruited and tested 404 home-dwelling drivers, aged 70xa0years or more and in possession of valid drivers’ licenses, who volunteered to participate in a driving refresher course. Forty-five drivers also agreed to undergo further testing at our lab. On-road driving performance was evaluated by instructors during a 45xa0minute validated open-road circuit. Drivers were classified as either being excellent, good, moderate, or poor depending on their score on a standardized evaluation of on-road driving performance.ResultsThe area under the receiver operator curve for detecting poorly performing drivers was 0.668 (CI95% 0.558 to 0.778) for the TMT-A, and 0.662 (CI95% 0.542 to 0.783) for the TMT-B. TMT was related to contrast sensitivity, motion direction, orientation discrimination, working memory, verbal fluency, and literacy. Older patients with a TMT-Au2009≥u200954xa0seconds or a TMT-Bu2009≥u2009150xa0seconds have a threefold (CI95% 1.3 to 7.0) increased risk of performing poorly during the on-road evaluation. TMT had a sensitivity of 63.6%, a specificity of 64.9%, a positive predictive value of 9.5%, and a negative predictive value of 96.9%.ConclusionIn screening settings, the TMT would have clinicians uselessly consider driving cessation in nine drivers out of ten. Given the important negative impact this could have on older drivers, this study confirms the TMT not to be specific enough for clinicians to justify driving cessation without complementary investigations on driving behaviors.

Theory of mind and social functioning in first episode psychosis

Introduction. There is evidence of associations between social functioning and theory of mind performance and between social functioning and negative symptoms in chronic psychosis. This study investigates these associations in those with first episode psychosis who are unaffected by factors related to long-term mental illness. Our first hypothesis states that there is an association between theory of mind and social functioning. The second hypothesis states that there is no association between symptoms of psychosis and social functioning. Methods. Fifty-two individuals with first episode psychosis were assessed for social functioning, theory of mind ability (using the Hinting test with verbal stimuli and the Visual Cartoon test with pictorial stimuli), and symptoms of psychosis. Multivariable logistic regression was used to examine associations. Results. Social functioning and theory of mind were associated when measured by the Hinting test (OR 1.70, 95% CI 1.08, 2.66), but not with the Visual Cartoon test (ToM jokes OR 0.61, 95% CI 0.15, 2.53). There was no association between social functioning and symptoms (psychotic symptoms; OR 0.95, 95% CI 0.81, 1.12; selected negative symptoms; OR 1.33, 95% CI 0.78, 2.25). Conclusions. Theory of mind assessed by verbal stimuli is associated with social functioning in a population with first episode psychosis. These findings may be related to language disorders in psychosis.

The longitudinal association between social functioning and theory of mind in first-episode psychosis

Introduction There is some cross-sectional evidence that theory of mind ability is associated with social functioning in those with psychosis but the direction of this relationship is unknown. This study investigates the longitudinal association between both theory of mind and psychotic symptoms and social functioning outcome in first-episode psychosis. Methods Fifty-four people with first-episode psychosis were followed up at 6 and 12 months. Random effects regression models were used to estimate the stability of theory of mind over time and the association between baseline theory of mind and psychotic symptoms and social functioning outcome. Results Neither baseline theory of mind ability (regression coefficients: Hinting test 1.07 95% CI −0.74, 2.88; Visual Cartoon test −2.91 95% CI −7.32, 1.51) nor baseline symptoms (regression coefficients: positive symptoms −0.04 95% CI −1.24, 1.16; selected negative symptoms −0.15 95% CI −2.63, 2.32) were associated with social functioning outcome. There was evidence that theory of mind ability was stable over time, (regression coefficients: Hinting test 5.92 95% CI −6.66, 8.92; Visual Cartoon test score 0.13 95% CI −0.17, 0.44). Conclusions Neither baseline theory of mind ability nor psychotic symptoms are associated with social functioning outcome. Further longitudinal work is needed to understand the origin of social functioning deficits in psychosis.

Inferring about individual drug and schizotypy effects on cognitive functioning in polydrug using mephedrone users before and after clubbing

Mephedrone has been recently made illegal in Europe, but little empirical evidence is available on its impact on human cognitive functions. We investigated acute and chronic effects of mephedrone consumption on drug‐sensitive cognitive measures, while also accounting for the influence of associated additional drug use and personality features.

Hemispheric Language Asymmetry in First Episode Psychosis and Schizotypy: The Role of Cannabis Consumption and Cognitive Disorganization

Cannabis use has been related to an elevated psychosis risk and attenuated cognitive functioning. Cannabis-related cognitive impairments are also observed in populations along the psychosis dimension. We here investigated whether a potential behavioral marker of the psychosis dimension (attenuated functional hemispheric asymmetry) is even further attenuated in individuals using cannabis (CU) vs those not using cannabis (nCU). We tested 29 patients with first-episode psychosis (FEP; 11 CU) and 90 healthy controls (38 CU) on lateralized lexical decisions assessing left-hemisphere language dominance. In patients, psychotic symptoms were assessed by Positive & Negative Symptom Scale (PANSS). In controls, self-reported schizotypy was assessed (The Oxford-Liverpool Inventory of Feelings and Experiences: O-LIFE). Results indicated that nCU FEP patients had a relative reduced hemispheric asymmetry, as did controls with increasing cognitive disorganization (CogDis) scores, in particular when belonging to the group of nCU controls. Positive, disorganized and negative PANSS scores in patients and negative and positive schizotypy in controls were unrelated to hemispheric asymmetry. These findings suggest that cannabis use potentially balances rather than exacerbates uncommon hemispheric laterality patterns. Moreover, in healthy populations, the potential stabilization of typical hemispheric asymmetry in CU might be most relevant to individuals with elevated CogDis. We discuss the potential beneficial and harmful effects of cannabis use along the psychosis dimension together with propositions for future studies that should account for the mediating role of additional substances (eg nicotine), cannabis composition (eg cannabidiol content), and individual differences (eg physical health, or absence of significant polysubstance use).

A neuropsychological instrument measuring age-related cerebral decline in older drivers: development, reliability, and validity of MedDrive

When facing age-related cerebral decline, older adults are unequally affected by cognitive impairment without us knowing why. To explore underlying mechanisms and find possible solutions to maintain life-space mobility, there is a need for a standardized behavioral test that relates to behaviors in natural environments. The aim of the project described in this paper was therefore to provide a free, reliable, transparent, computer-based instrument capable of detecting age-related changes on visual processing and cortical functions for the purposes of research into human behavior in computational transportation science. After obtaining content validity, exploring psychometric properties of the developed tasks, we derived (Study 1) the scoring method for measuring cerebral decline on 106 older drivers aged ≥70 years attending a driving refresher course organized by the Swiss Automobile Association to test the instruments validity against on-road driving performance (106 older drivers). We then validated the derived method on a new sample of 182 drivers (Study 2). We then measured the instruments reliability having 17 healthy, young volunteers repeat all tests included in the instrument five times (Study 3) and explored the instruments psychophysical underlying functions on 47 older drivers (Study 4). Finally, we tested the instruments responsiveness to alcohol and effects on performance on a driving simulator in a randomized, double-blinded, placebo, crossover, dose-response, validation trial including 20 healthy, young volunteers (Study 5). The developed instrument revealed good psychometric properties related to processing speed. It was reliable (ICC = 0.853) and showed reasonable association to driving performance (R2 = 0.053), and responded to blood alcohol concentrations of 0.5 g/L (p = 0.008). Our results suggest that MedDrive is capable of detecting age-related changes that affect processing speed. These changes nevertheless do not necessarily affect driving behavior.

The effects of aging on perception and cognition

The developed world is aging faster than ever before. Even in the absence of neurodegenerative disease, aging affects all kinds of human functions including perception and cognition. In most perceptual studies, one paradigm is tested and it is usually found that older participants perform worse than younger participants. Implicitly, these results are taken as evidence that there is one aging factor for each individual determining his/her overall performance levels. Here, we show that visual and cognitive functions age differently. We tested 131 older participants (mean age 70 years old) and 108 younger participants (mean age 22 years old) in 14 perceptual tests (including motion perception, contrast and orientation sensitivity, biological motion perception) and in 4 cognitive tasks (MoCA, WCST, verbal fluency and digit span). Young participants performed better than older participants in almost all of the tests. However, within the older participants group, age did not predict performance, i.e., a participant could have good results in biological motion perception but poor results in orientation discrimination. It seems that there is not a single aging factor but many. Meeting abstract presented at VSS 2015.

Stressing schizotypy: The modulating role of stress-relieving behaviours and intellectual capacity on functional hemispheric asymmetry

Relative cognitive impairments are common along the schizophrenia spectrum reflecting potential psychopathological markers. Yet stress, a vulnerability marker in schizophrenia (including its spectrum), is likewise related to cognitive impairments. We investigated whether one such cognitive marker (attenuated functional hemispheric asymmetry) during stressful life periods might be linked to individuals schizotypal features or rather to individuals stress-related experiences and behaviours. A total of 58 students performed a left hemisphere dominant (lateralised lexical decisions) and right hemisphere dominant (sex decisions on composite faces) task. In order to account for individual differences in stress sensitivity we separated participants into groups of high or low cognitive reserve according to their average current marks. In addition, participants filled in questionnaires on schizotypy (short O-LIFE), perceived stress, stress response, and a newly adapted questionnaire that enquired about potential stress compensation behaviour (elevated substance use). The most important finding was that enhanced substance use and cognitive disorganisation contributed to a right and left hemisphere shift in language dominance, respectively. We discuss that (i) former reports on right hemisphere shifts in language dominance with positive schizotypy might be explained by an associated higher substance use and (ii) cognitive disorganisation relates to unstable cognitive functioning that depend on individuals life circumstances, contributing to published reports on inconsistent laterality–schizotypy relationships.