Peter Scherzer

Predictors and indicators of work status after traumatic brain injury: A meta-analysis

Abstract Heterogeneity of studies reporting data about predictive and indicative variables of return to work after traumatic brain injury led to a lack of clarity and reliability. A meta-analysis was performed to integrate and organise the results of studies reporting data about the relation between variables that are conceptually meaningful in rehabilitation and a dichotomous criteria of work status: employed or unemployed. The large quantity of variables were grouped chronologically according pre-, peri and post-traumatic phases. The results indicate that the highest and most reliable correlations were between unemployment and executive dysfunctions, emotional disturbances, deficits in activities of daily living, and less vocational rehabilitation services. Other variables, such as anosmia and post-coma activity level, show high correlations but are still to be corroborated.

Assessment of social cognition in patients with multiple sclerosis

We examined the capacity of patients with multiple sclerosis (MS) to attribute mental states to others and to identify cognitive abilities that subserve theory of mind (ToM). In this article, we report findings on 41 out-patients with diagnosed MS who underwent detailed neuropsychological and social-cognitive assessment. They were subdivided into a cognitively intact (n=15) and cognitively impaired (n=26) group according to their neuropsychological test results. Their results were compared with those of 20 age- and education-matched controls. MS patients with cognitive impairments were found to have more difficulties attributing mental states to others than did cognitively intact MS patients and normal controls on two ToM measures; short stories (Happé, Winner, & Brownell, 1998) and video clips (Ouellet, Bédirian, Charbonneau, & Scherzer, 2009). When attention, memory, and working memory were controlled, performance on the WAIS-III Picture Arrangement task accounted for 17.3% of the variance in performance on the video clips task. Performance on a WAIS-III index composed of Similarities and Comprehension subtests, accounted for 7.0% of the variance in performance on the short stories task. These results provide some preliminary information on the effect of MS-related cognitive deficits on the ability to attribute mental states to others.

A Study of Theory of Mind in Paranoid Schizophrenia: A Theory or Many Theories?

Social cognitive psychologists (Frith, 1992; Hardy-Baylé et al., 2003) sought to explain the social problems and clarify the clinical picture of schizophrenia by proposing a model that relates many of the symptoms to a problem of metarepresentation, i.e., theory of mind (ToM). Given the differences in clinical samples and results between studies, and considering the wide range of what is considered to constitute ToM, one must ask if there a core function, or is ToM multifaceted with dissociable facets? If, there are dissociable dimensions or facets, which are affected in patients with paranoid schizophrenia? To answer these questions, a group of 21 individuals diagnosed with paranoid schizophrenia and 29 non-clinical control subjects, were tested on a battery of five different measures of ToM. The results confirmed that there was little difference in specificity of three of the tests in distinguishing between the clinical and non-clinical group, but there were important differences in the shared variance between the tests. Further analyses hint at two dimensions although a single factor with the same variance and the same contributing weights in both groups could explain the results. The deficits related to the attribution of cognitive and affective states to others inferred from available verbal and non-verbal information. Further analyses revealed that incorrect attributions of mental states including the attribution of threatening intentions to others, non-interpretative responses and incomplete answers, depending on the test of ToM.

Intelligence measures and stage 2 sleep in typically-developing and autistic children

The relationship between intelligence measures and 2 EEG measures of non-rapid eye movement sleep, sleep spindles and Sigma activity, was examined in 13 typically-developing (TD) and 13 autistic children with normal IQ and no complaints of poor sleep. Sleep spindles and Sigma EEG activity were computed for frontal (Fp1, Fp2) and central (C3, C4) recording sites. Time in stage 2 sleep and IQ was similar in both groups. Autistic children presented less spindles at Fp2 compared to the TD children. TD children showed negative correlation between verbal IQ and sleep spindle density at Fp2. In the autistic group, verbal and full-scale IQ scores correlated negatively with C3 sleep spindle density. The duration of sleep spindles at Fp1 was shorter in the autistic group than in the TD children. The duration of sleep spindles at C4 was positively correlated with verbal IQ only in the TD group. Fast Sigma EEG activity (13.25-15.75 Hz) was lower at C3 and C4 in autistic children compared to the TD children, particularly in the latter part of the night. Only the TD group showed positive correlation between performance IQ and latter part of the night fast Sigma activity at C4. These results are consistent with a relationship between EEG activity during sleep and cognitive processing in children. The difference between TD and autistic children could derive from dissimilar cortical organization and information processing in these 2 groups.

Eye-Hand Coordination in Aging and in Parkinson’s Disease

Aiming movements to defined target positions were performed as fast and as accurately as possible by younger and older subjects and by patients in the early stages of Parkinsons disease (PD). Movement time and accuracy were tested in two conditions: with and without a centre cue. Older subjects exhibited slower movement time relative to the younger subjects only when the centre cue was present suggesting inefficient feedback processing. The performance of patients with PD was found to be as precise as that of older subjects. The movements of PD subjects, however, were slower in both conditions. Finally, the performance of subjects improved over trials. The data suggest that there is no difference in the nature of the control processes used by older and early-stage PD subjects, but that there is a reduction in the speed of these processes in PD.

Two Routes to Losing One’s Past Life: A Brain Trauma, an Emotional Trauma

Organic and psychogenic retrograde amnesia have long been considered as distinct entities and as such, studied separately. However, patterns of neuropsychological impairments in organic and psychogenic amnesia can bear interesting resemblances despite different aetiologies. In this paper, two cases with profound, selective and permanent retrograde amnesia are presented, one of an apparent organic origin and the other with an apparent psychogenic cause. The first case, DD, lost his memory after focal brain injury from a nail gun to the right temporal lobe. The second case, AC, lost her memory in the context of intense psychological suffering. In both cases, pre-morbid autobiographical memory for people, places and events was lost, and no feeling of familiarity was experienced during relearning. In addition, they both lost some semantic knowledge acquired prior to the onset of the amnesia. This contrasts with the preservation of complex motor skills without any awareness of having learned them. Both DD and AC showed mild deficits on memory tests but neither presented any anterograde amnesia. The paradox of these cases–opposite causes yet similar clinical profile–exemplifies the hypothesis that organic and psychogenic amnesia may be two expressions of the same faulty mechanism in the neural circuitry.

A Verbal Planning Impairment in Adult ADHD Indexed by Script Generation Tasks

Objective: Though juvenile and adult ADHD cases are well known to have a nonverbal planning impairment, a verbal-planning impairment has been demonstrated only in juvenile ADHD. The purpose of this investigation is to determine whether a verbal planning impairment also characterizes adult ADHD. Methods: A cohort of 30 adult ADHD clients of a university psychological clinic are compared to 30 age-, education-, gender-, and IQ-matched persons recruited from the general population who did not have ADHD. The dependent measure is a set of 6 paper/pencil 10-item script generation tasks. Results: The findings reveal that the ADHD cohort was significantly impaired on the script task and the script task correlated significantly with severity of ADHD (CAARS index + WURS), whereas several neuropsychological measures of executive function (Stroop, COWA, Rey’s Complex Figure, D2, CVLT, CPT-II) did not. Findings further showed that the script measure was weakly correlated with the other established neuropsychological measures of executive function (r < .46, shared variance of less than 21%). Conclusions: On the basis of the study findings, it is concluded that verbal planning measured with script generation tasks is distinctly impaired in clinically referred adult ADHD.

REM sleep and emotional face memory in typically-developing children and children with autism

Relationship between REM sleep and memory was assessed in 13 neurotypical and 13 children with Autistic Spectrum Disorder (ASD). A neutral/positive/negative face recognition task was administered the evening before (learning and immediate recognition) and the morning after (delayed recognition) sleep. The number of rapid eye movements (REMs), beta and theta EEG activity over the visual areas were measured during REM sleep. Compared to neurotypical children, children with ASD showed more theta activity and longer reaction time (RT) for correct responses in delayed recognition of neutral faces. Both groups showed a positive correlation between sleep and performance but different patterns emerged: in neurotypical children, accuracy for recalling neutral faces and overall RT improvement overnight was correlated with EEG activity and REMs; in children with ASD, overnight RT improvement for positive and negative faces correlated with theta and beta activity, respectively. These results suggest that neurotypical and children with ASD use different sleep-related brain networks to process faces.

Working memory for Braille is shaped by experience

Tactile working memory was found to be more developed in completely blind (congenital and acquired) than in semi-sighted subjects, indicating that experience plays a crucial role in shaping working memory. A model of working memory, adapted from the classical model proposed by Baddeley and Hitch (1) and Baddeley (2), is presented where the connection strengths of a highly cross-modal network are altered through experience.

Evidence from paranoid schizophrenia for more than one component of theory of mind

We previously reported finding that performance was impaired on four out of five theory of mind (ToM) tests in a group of 21 individuals diagnosed with paranoid schizophrenia (pScz), relative to a non-clinical group of 29 individuals (Scherzer et al., 2012). Only the Reading the Mind in the Eyes Test did not distinguish between groups. A principal components analysis revealed that the results on the ToM battery could be explained by one general ToM factor with the possibility of a latent second factor. As well, the tests were not equally sensitive to the pathology. There was also overmentalization in some ToM tests and under-mentalisation in others. These results led us to postulate that there is more than one component to ToM. We hypothesized that correlations between the different EF measures and ToM tests would differ sufficiently within and between groups to support this hypothesis. We considered the relationship between the performance on eight EF tests and five ToM tests in the same diagnosed and non-clinical individuals as in the first study. The ToM tests shared few EF correlates and each had its own best EF predictor. These findings support the hypothesis of multiple ToM components.