Burghard Andresen

Impaired modulation of the saccadic contingent negative variation preceding antisaccades in schizophrenia.

BACKGROUND The contingent negative variation (CNV) is considered to reflect prefrontal functioning and can be observed before manual and ocular motor responses. Schizophrenic patients exhibit reduced CNV amplitudes in tasks requiring manual motor responses. A number of studies has also found normal prosaccades, but delayed antisaccades and an augmented rate of erroneous prosaccades during the antisaccade task in schizophrenia. In this study we examined the CNV during pro- and antisaccade tasks in schizophrenic patients and healthy control subjects. METHODS Data of 17 medicated schizophrenics (ICD-10, F20) and 18 control subjects, matched with patients for age, gender, and education were analyzed. Horizontal pro- and antisaccades were elicited in four blocks, each consisting of 80 trials. Electroencephalogram was recorded from 32 channels with a DC amplifier. RESULTS Patients exhibited delayed correct responses and more erroneous prosaccades during the antisaccade task than control subjects, but normal prosaccadic reaction times. In control subjects, the vertex-predominant saccadic CNV was generally larger than in patients, and larger during the anti- than during the prosaccade task. This task-related amplitude augmentation was absent in patients. Analyses of additional components suggested specificity of impaired event-related potential modulation to the saccadic CNV. CONCLUSIONS In accordance with the presumed prefrontal dysfunction, our results suggest deficient preparation and execution of antisaccades in schizophrenia.

Neuropsychological correlates of schizophrenic syndromes in patients treated with atypical neuroleptics.

There is widespread evidence that schizophrenic symptomatology is best represented by three syndromes (positive, negative, disorganized). Both the disorganized and negative syndrome have been found to correlate with several neurocognitive dysfunctions. However, previous studies investigated samples predominantly treated with typical neuroleptics, which frequently induce parkinsonian symptoms that are hard to disentangle from primary negative symptoms and may have inflated correlations with neurocognition. A newly developed psychopathological instrument called the Positive and Negative and Disorganized Symptoms Scale (PANADSS) was evaluated in 60 schizophrenic patients. Forty-seven participants treated with atypical neuroleptics performed several neurocognitive tasks.A three-factor solution of schizophrenic symptomatology emerged. Negative symptomatology was associated with diminished creative verbal fluency and digit span backward, whereas disorganization was significantly correlated with impaired Stroop, WCST and Trail-Making Test B performance.Data suggest that disorganization is associated with tasks that demand executive functioning. Previous findings reporting correlations between negative symptomatology and neurocognition may have been confounded by the adverse consequences of typical neuroleptics.

Neurocognitive performance in first-episode and chronic schizophrenic patients.

Previous research on neuropsychological disturbances in first-episode and chronic schizophrenic patients has provided mixed results which can be partially attributed to methodological inconsistencies. For the present study, 70 schizophrenic patients (40 with chronic and 30 with first-episode schizophrenia) were compared to 30 healthy controls on a large battery of neuropsychological tests. Special attention was paid to potential confounds such as differences in psychopathology, age and educational level between the schizophrenic sub-samples.Healthy controls performed better than both first-episode and chronic patients in almost all cognitive domains (P < 0.01), while the patient samples did not differ in any of the tasks. Results were confirmed in a second series of analyses in which patient subgroups were equated for sociodemographic background variables. The present results confirm recent data collected in longitudinal studies, thus, lending further support for a neurodevelopmental model of schizophrenia. It is suggested that neuropsychological disturbances occur early in schizophrenia and do not worsen in the course beyond age-related decrement. Possible reasons why previous research has produced contradictory findings are discussed.

Negative priming in schizophrenia: effects of masking and prime presentation time

Beech et al. [Br. J. Clin. Psychol. 28 (1989) 109--116] previously reported attenuated negative priming in schizophrenic patients that was interpreted as a sign of dysfunctional cognitive inhibition. However, subsequent research has provided mixed results. In the present study, it was investigated whether reduced negative priming in schizophrenics may be an experimental artifact. Based on evidence from backward masking studies in schizophrenia, it was hypothesized that brief prime presentation times and pattern masking as used by Beech et al. and others may have impaired the visual perception of the prime display in schizophrenics. 20 schizophrenic patients and 20 matched healthy controls participated in the study. Subjects completed four negative priming experiments varying in prime presentation time (100 or 250 ms) and masking (a mask or a blank screen followed prime presentation). In line with prediction, reduced negative priming in schizophrenics only occurred for trials with 100 ms prime presentation time followed by a mask. Neither psychopathology nor any sociodemographic variable correlated substantially with negative priming. Results strongly suggest that reduced negative priming in schizophrenics may not be due to reduced cognitive inhibition but mirrors perceptual deficits.

Topography of CNV and PINV in schizotypal personality

The topography of the postimperative negative variation (PINV) was analyzed in participants with high and low scores on the German version of the Schizotypal Personality Questionnaire. Scalp amplitude and Laplacian maps of the terminal contingent negative variation (tCNV) and PINV and the time course of the PINV were compared between the two groups. CNV and PINV were induced with a delayed matching-to-sample task, in which the pattern of the imperative stimulus was either clearly or ambiguous matched to one of the two diamonds simultaneously presented as a warning stimulus 4.0 s earlier. Electroencephalograms were recorded with a DC amplifier (32 channels). Negativity increased from tCNV to PINV, especially at frontal sites, and the PINV was larger under ambiguous than under clear matching conditions. Low-scoring participants showed a right-sided predominance of the PINV, which was absent in high-scoring participants. These results resemble differences in the topography of the PINV between healthy control participants and those with schizophrenia under identical experimental conditions and suggest functional differences between tCNV and PINV.

Extent, profile and specificity of visuospatial impairment in obsessive-compulsive disorder (OCD)

Recent reviews on the neurocognitive profile of patients diagnosed with obsessive-compulsive disorder (OCD) have converged on the assumption that both visuospatial and especially nonverbal memory performance are impaired in OCD. However, as most prior studies have contrasted performance of OCD patients with healthy controls only, no inferences can yet be drawn about the specificity of these deficits to OCD. Further, the administration of complex and multifunctional tasks limit conclusions about clearly defined cognitive deficits. The present study compared 71 OCD patients to 30 healthy and 33 psychiatric control participants on a large battery of visuospatial and nonverbal memory tasks at two time-points. In addition, a visuospatial battery (VS battery), which assesses a wide range of elementary visuospatial functions, was administered. While OCD patients performed worse than healthy controls on some complex tasks (e.g., Block Design), no visuospatial component proved to be impaired specifically in OCD. OCD patients and controls performed similarly on parameters of nonverbal memory. Regarding organizational strategy, OCD patients performed worse than healthy (but not psychiatric) control participants on two out of three Rey-figure trials (copy and immediate). It is suggested that prior research overestimated the severity and significance of visuospatial and nonverbal memory impairment in OCD. The authors would like to thank Dr. Michael Rufer, Dr. Angelique Mundt and Jürgen Orthmann for help with recruitment. The study was supported by a grant of the German Research Foundation (MO 969/1-1).

Neuropsychological Correlates of Schizotypal Disorganisation

Introduction. Psychometric studies confirm that cognitive deviations commonly reported in schizophrenics are also detectable in healthy subjects exhibiting elevated scores in questionnaires assessing schizotypal personality. In the present study, a relationship between three cognitive tasks and schizotypy was investigated predicting that schizotypal disorganisation would be associated with deficits in the trail-making B and Stroop task in accordance with previous results obtained with schizophprenics. Methods. Prior to completing the Schizotypal Personality Questionnaire (SPQ), a measure designed according to the DSM-III-R criteria of schizotypal personality disorder, a group of healthy subjects performed the Stroop task (n = 160) and the trail-making tests A and B (n = 80). Results. Disorganisation as assessed with two SPQ-subscales was significantly correlated with slowness in the trail-making test A and the Stroop task before and after correction for some possible confounds. A significant correlation b...

Neuroleptic-induced extrapyramidal symptoms are accompanied by cognitive dysfunction in schizophrenia

Cognitive impairments in schizophrenics have been found to precede tardive dyskinesia and to co-exist with other motor deficits. However, little is yet known about the prevalence of cognitive disturbances in patients with neuroleptic-induced parkinsonism. From the literature on idiopathic parkinson, it was inferred that extrapyramidal symptoms (EPS) are accompanied by cognitive dysfunction. 85 schizophrenic in-patients were divided into EPS high and low scorers according to an established criterion (Simpson Angus Scale, cut-off score: 0.4). Cognitive impairments were assessed using a self-rating instrument measuring disturbances of information processing. Patients with high EPS exhibited significantly elevated scores in six of ten cognitive and perceptual subscales (t = 2.1-3.1) as compared to low EPS patients. It is concluded that high EPS patients suffer from cognitive disturbances which are assumed to possess high relevance for both psycho-social and medical treatment. Cognitive problems may, when not considered, disturb compliance, insight of illness and transfer of learnt skills into everyday life.

Considering DSM-5: Personality Diagnostics in Patients with Schizophrenia Spectrum Disorders

Abstract The aims of this study were to examine the prevalence of personality disorders (PD) in patients with schizophrenia spectrum disorders (SSD), to examine the interaction of axis-I and axis-II symptoms to provide an estimate on the confounding potential of SSD psychopathology in the establishment of DSM-IV PD diagnoses, and to discuss implications concerning the proposed changes in DSM-5. Patients with SSD, aged 18 to 65 years, and being at least partially remitted (PANSS total score < 75) were included. PD was examined categorically and dimensionally using the SCID-II screening questionnaire and interview, and SSD psychopathology was rated using the Positive and Negative Syndrome Scale for Schizophrenia (PANSS). Forty-five patients (31 with schizophrenia) were included in the current study. Mean age was 37.2 years, and the median duration of illness was 9.5 years. Mean PANSS total score was 42.5. The cumulative prevalence of PD in our collective was 20%, with obsessive-compulsive, antisocial, and borderline PD being the most frequent. There were no cases of cluster A PD diagnoses. In the dimensional analysis, numerous correlations of small to medium effect size emerged between maladaptive personality traits and SSD psychopathology. PD is present in a clinically relevant subgroup of SSD patients and has to be recognized in SSD treatment. Currently, it remains unclear to what extent correlations between personality traits and SSD symptoms can be explained by content overlap or co-variation of SSD psychopathology and PD traits. SSD psychopathology may bias PD diagnostics and lead to a higher percentage of categorical PD diagnoses, especially considering the proposed changes in DSM-5.

Evidence of Neurotoxicity of Ecstasy: Sustained Effects on Electroencephalographic Activity in Polydrug Users

Objective According to previous EEG reports of indicative disturbances in Alpha and Beta activities, a systematic search for distinct EEG abnormalities in a broader population of Ecstasy users may especially corroborate the presumed specific neurotoxicity of Ecstasy in humans. Methods 105 poly-drug consumers with former Ecstasy use and 41 persons with comparable drug history without Ecstasy use, and 11 drug naives were investigated for EEG features. Conventional EEG derivations of 19 electrodes according to the 10-20-system were conducted. Besides standard EEG bands, quantitative EEG analyses of 1-Hz-subdivided power ranges of Alpha, Theta and Beta bands have been considered. Results Ecstasy users with medium and high cumulative Ecstasy doses revealed an increase in Theta and lower Alpha activities, significant increases in Beta activities, and a reduction of background activity. Ecstasy users with low cumulative Ecstasy doses showed a significant Alpha activity at 11 Hz. Interestingly, the spectral power of low frequencies in medium and high Ecstasy users was already significantly increased in the early phase of EEG recording. Statistical analyses suggested the main effect of Ecstasy to EEG results. Conclusions Our data from a major sample of Ecstasy users support previous data revealing alterations of EEG frequency spectrum due rather to neurotoxic effects of Ecstasy on serotonergic systems in more detail. Accordingly, our data may be in line with the observation of attentional and memory impairments in Ecstasy users with moderate to high misuse. Despite the methodological problem of polydrug use also in our approach, our EEG results may be indicative of the neuropathophysiological background of the reported memory and attentional deficits in Ecstasy abusers. Overall, our findings may suggest the usefulness of EEG in diagnostic approaches in assessing neurotoxic sequela of this common drug abuse.