Burkhard Wiebel

Ruhr-Universität Bochum, Bochum, North Rhine-Westphalia, Germany

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Publications (6)17.07 Total impact

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    Wiebel B
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    ABSTRACT: The objective of the study was to test the assumption that patients with a high level of negative symptoms show disproportionate impairments of inhibition and multitasking, both representing an underlying context processing mechanism. A total of 26 schizophrenia patients scoring high or low on negative symptoms (Positive and Negative Syndrome Scale) and a group of 13 healthy controls were assessed on measures of response inhibition (AX- Continuous Performance Task, Stroop Test) and multitasking (Dual Task, Trail Making Test). Only the high negative symptoms group showed significantly higher inhibition costs and multitasking costs than healthy controls. In the AX-Continuous Performance Test, inhibition costs exceeded context costs in patients with more severe negative symptoms, while in controls a tendency towards the reverse pattern emerged. There were no statistically significant effects involving the patient group with lower negative symptom scores. The pattern of results suggests that primarily patients with more severe negative symptoms have difficulties benefiting from contextual information. The deficit may manifest itself via increased multitasking costs and increased inhibition costs but also via reduced context costs.
    Journal of Clinical and Experimental Neuropsychology 06/2007; 29(4):428-35. · 2.16 Impact Factor
  • Patrizia Thoma, Burkhard Wiebel, Irene Daum
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    ABSTRACT: Addiction is a frequent comorbid disorder in schizophrenia related to dopaminergic dysfunction in fronto-subcortical circuits. These brain networks are relevant for both (executive) cognition and the neuropathology of schizophrenia. The aim of the present study was to elucidate whether response inhibition and cognitive flexibility - executive abilities relevant for achieving and maintaining abstinence - are differentially impaired in schizophrenia patients with or without comorbid substance use disorder. Patients suffering from major depression or alcoholism as well as healthy controls served as comparison groups. The ability to inhibit predominant response tendencies during response conflict and to efficiently shift the focus of attention between different task requirements was assessed by verbal and non-verbal cognitive tasks. Contrary to expectation, non-addicted schizophrenia patients showed the most pronounced executive function impairments relative to the control groups, affecting both response suppression and cognitive flexibility. Dual diagnosis patients did not differ significantly from non-addicted schizophrenia patients or from the alcoholic group, but were impaired at cognitive flexibility relative to the depression subgroup and healthy controls. Whether the relative preservation of response inhibition and cognitive flexibility in the dual disorder patients is due to high premorbid functioning, beneficial self-medication effects or compensatory brain activation remains to be elucidated. The relatively intact executive abilities in young, addicted schizophrenia patients might represent a beneficial resource for treatment strategies.
    Schizophrenia Research 05/2007; 92(1-3):168-80. · 4.43 Impact Factor
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    ABSTRACT: Using the "remember-know" procedure to assess recognition memory, previous studies yielded evidence of impaired recollection but intact familiarity in schizophrenia patients. However, so far, the recognition memory performance of schizophrenia patients has not yet been analysed using the dual-process signal detection model (DPSD) by Yonelinas [Yonelinas, A. P. (2001). Components of episodic memory: The contribution of recollection and familiarity. Philosophical Transactions of Royal Society of London. Series B: Biological Sciences, 356(1413), 1363-1374], which accurately accounts for response and memory bias. Also, clinical symptoms have not yet been taken into account. Based on findings from neuropsychological and neurobiological research we hypothesized that high negative symptoms might be associated with a profile of impaired recollection and spared familiarity. The recognition memory performance of 22 schizophrenia patients scoring higher or lower on the negative symptoms subscale of the Positive and Negative Syndrome Scale (PANSS) was assessed by means of a word list discrimination task. Following the rationale of the dual-process signal detection model, estimates of recollection and familiarity were derived. The recollection estimate, derived by the DPSD model, was lower in patients with more severe negative symptomatology compared with both the patients with lower negative symptoms scores and healthy individuals. Familiarity was not affected if IQ was partialled out. Furthermore, the results yielded increased false alarm rates in patients with negative schizophrenia. The findings confirm an association of negative symptoms and recollection impairment in schizophrenia.
    Neuropsychologia 02/2006; 44(3):430-5. · 3.45 Impact Factor
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    ABSTRACT: Studies on cognitive processes in alcoholism have reported changes with respect to executive functions and memory, which have been interpreted within the context of different neuropsychological models. The aims of the present study were to investigate (1) the validity of these models and (2) the influence of depression on cognitive functioning in alcoholism. In the present investigation, patients suffering from alcoholism (Alc; n = 30), patients with depression but without alcoholism (Dep; n = 28) and healthy controls (HC; n = 28) were compared on a neuropsychological test battery. The test battery included measurements of mood, memory and executive functions. The possible cumulative effect of alcohol and depression was analysed by comparison of depressed alcoholic patients (Dalc) and non-depressed alcoholic patients (NDAlc). Group comparisons revealed impairments of alcoholic patients with respect to response inhibition, reasoning and free recall, irrespective of depression. Priming, short-term memory as well as verbal fluency abilities were unaffected. Depressive patients showed verbal fluency as well as free recall deficits. However, there was no difference in performance between depressed and non-depressed alcoholics. The specific pattern of neuropsychological deficits of the alcoholic patients supports the frontal lobe hypothesis. The results of the present investigation suggest that these deficits are not generally exacerbated by comorbid depressive symptoms. Further studies, however, are desirable to investigate the relation between executive deficits and depression in alcoholics with evidence of major depression.
    Addiction 12/2003; 98(11):1521-9. · 4.60 Impact Factor
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    ABSTRACT: Studies on neuropsychological functions in early Parkinson's disease (PD) have reported changes with respect to memory and executive control related to dysfunction of fronto-striatal circuitry. The question has been raised, however, whether these findings are at least partly influenced by depression, which as such can also lead to cognitive impairments that depend on the functional integrity of the prefrontal cortex. In the present investigation early non-depressed PD patients (NPD), early PD patients with mild depressive symptoms (DPD), patients with primary depression (DEP) and healthy controls (HC) completed a range of neuropsychological tests. Group comparisons revealed impairments of DPD patients in comparison with HC with respect to verbal fluency, short-term memory and concept formation. In addition they showed mild working-memory deficits. In summary the present results indicate that depressed mood in early PD may exacerbate cognitive impairments. Thus careful assessment of affective variables in PD should be an integral part of the treatment of PD.
    Acta Neurologica Scandinavica 06/2003; 107(5):341-8. · 2.44 Impact Factor