Stefan Kaiser

University of Zurich, Zürich, Zurich, Switzerland

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Publications (63)190.71 Total impact

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    ABSTRACT: Negative symptoms can be grouped into the two dimensions of diminished expression and apathy, which have been shown to be dissociable regarding external validators, such as functional outcome. Here, we investigated whether these two dimensions differentially relate to neurocognitive impairment in schizophrenia. 47 patients with schizophrenia or schizoaffective disorder and 33 healthy control participants were subjected to a neurocognitive test battery assessing multiple cognitive domains (processing speed, working memory, verbal fluency, verbal learning and memory, mental planning), which are integrated into a composite cognition score. Negative symptoms in patients were assessed using the Brief Negative Symptom Scale. We found that diminished expression significantly related to neurocognitive impairment, while severity of apathy symptoms was not directly associated with neurocognition. Other assessed clinical variables include chlorpromazine equivalents, positive symptoms, and depressive symptoms and did not influence the results. Our results are in line with a cognitive resource limitation model of diminished expression in schizophrenia and indicate that cognitive remediation therapy might be helpful to ameliorate expressive deficits.
    No preview · Article · Nov 2015 · Schizophrenia Research
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    ABSTRACT: Apathy, a quantitative reduction in goal-directed behavior, is a prevalent symptom dimension with a negative impact on functional outcome in various neuropsychiatric disorders including schizophrenia and depression. The aim of this review is to show that interview-based assessment of apathy in humans and observation of spontaneous rodent behavior in an ecological setting can serve as an important complementary approach to already existing task-based assessment, to study and understand the neurobiological bases of apathy. We first discuss the paucity of current translational approaches regarding animal equivalents of psychopathological assessment of apathy. We then present the existing evaluation scales for the assessment of apathy in humans and propose five sub-domains of apathy, namely self-care, social interaction, exploration, work/education and recreation. Each of the items in apathy evaluation scales can be assigned to one of these sub-domains. We then show that corresponding, well-validated behavioral readouts exist for rodents and that, indeed, three of the five human apathy sub-domains have a rodent equivalent. In conclusion, the translational ecological study of apathy in humans and rodents is possible and will constitute an important approach to increase the understanding of the neurobiological bases of apathy and the development of novel treatments.
    Full-text · Article · Oct 2015 · Frontiers in Behavioral Neuroscience
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    ABSTRACT: Background: Negative symptoms of schizophrenia can be grouped in 2 dimensions: apathy and diminished expression. Increasing evidence suggests that negative symptoms are associated with altered neural activity of subcortical and cortical regions in the brain reward system. However, the neurobiological basis of the distinct symptom dimensions within negative symptoms is still poorly understood. The primary aim of our study was to examine the neural correlates of the negative symptom dimensions apathy and diminished expression during a reward processing task. Methods: Patients with schizophrenia and healthy controls underwent event-related fMRI while performing a variant of the Monetary Incentive Delay Task. We assessed negative symptom dimensions using the Brief Negative Symptom Scale. Results: We included 27 patients and 25 controls in our study. Both groups showed neural activation indicated by blood oxygen-level dependent signal in the ventral striatum during reward anticipation. Ventral striatal activation during reward anticipation showed a strong negative correlation with apathy. Importantly, this effect was not driven by cognitive ability, medication, depressive or positive symptoms. In contrast, no significant correlation with the diminished expression dimension was observed. Limitations: Although the results remain significant when controlling for chlorpromazine equivalents, we cannot fully exclude potential confounding effects of medication with atypical antipsychotics. Conclusion: The specific correlation of ventral striatal hypoactivation during reward anticipation with apathy demonstrates a differentiation of apathy and diminished expression on a neurobiological level and provides strong evidence for different pathophysiological mechanisms underlying these 2 negative symptom dimensions. Our findings contribute to a multilevel framework in which apathy and motivational impairment in patients with schizophrenia can be described on psychopathological, behavioural and neural levels.
    No preview · Article · Sep 2015 · Journal of psychiatry & neuroscience: JPN

  • No preview · Article · Sep 2015
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    ABSTRACT: The negative symptoms of schizophrenia have been associated with altered neural activity during both reward processing and cognitive processing. Even though increasing evidence suggests a strong interaction between these two domains, it has not been studied in relation to negative symptoms. To elucidate neural mechanisms of the reward-cognition interaction, we applied a letter variant of the n-back working memory task and varied the financial incentives for performance. In the interaction contrast, we found a significantly activated cluster in the rostral anterior cingulate cortex (ACC), the middle frontal gyrus, and the bilateral superior frontal gyrus. The interaction did not differ significantly between the patient group and a healthy control group, suggesting that patients with schizophrenia are on average able to integrate reward information and utilize this information to maximize cognitive performance. However within the patient group, we found a significant inverse correlation of ACC activity with the factor diminished expression. This finding is consistent with the model that a lack of available cognitive resources leads to diminished expression. We therefore argue that patients with diminished expression have difficulties in recruiting additional cognitive resources (as implemented in the ACC) in response to an anticipated reward. Due to this lack of cognitive resources, less processing capacity is available for effective expression, resulting in diminished expressive behavior.
    No preview · Article · Sep 2015 · Schizophrenia Research
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    ABSTRACT: Dysfunctional patterns of activation in brain reward networks have been suggested as a core element in the pathophysiology of schizophrenia. However, it remains unclear whether this dysfunction is specific to schizophrenia or can be continuously observed across persons with different levels of nonclinical and clinical symptom expression. Therefore, we sought to investigate whether the pattern of reward system dysfunction is consistent with a dimensional or categorical model of psychosis-like symptom expression. 23 patients with schizophrenia and 37 healthy control participants with varying levels of psychosis-like symptoms, separated into 3 groups of low, medium, and high symptom expression underwent event-related functional magnetic resonance imaging while performing a Cued Reinforcement Reaction Time task. We observed lower activation in the ventral striatum during the expectation of high vs no reward to be associated with higher symptom expression across all participants. No significant difference between patients with schizophrenia and healthy participants with high symptom expression was found. However, connectivity between the ventral striatum and the medial orbitofrontal cortex was specifically reduced in patients with schizophrenia. Dysfunctional local activation of the ventral striatum depends less on diagnostic category than on the degree of symptom expression, therefore showing a pattern consistent with a psychosis continuum. In contrast, aberrant connectivity in the reward system is specific to patients with schizophrenia, thereby supporting a categorical view. Thus, the results of the present study provide evidence for both continuous and discontinuous neural substrates of symptom expression across patients with schizophrenia and the general population. © The Author 2015. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.
    Full-text · Article · May 2015 · Schizophrenia Bulletin
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    ABSTRACT: Negative symptoms are a core feature of schizophrenia and have been grouped into two factors: a motivational factor, which we refer to as apathy, and a diminished expression factor. Recent studies have shown that apathy is closely linked to functional outcome. However, knowledge about its mechanisms and its relation to decision-making is limited. In the current study, we examined whether apathy in schizophrenia is associated with predecisional deficits, that is, deficits in the generation of options for action. We applied verbal protocol analysis to investigate the quantity of options generated in ill-structured real world scenarios in 30 patients with schizophrenia or schizoaffective disorder and 21 healthy control participants. Patients generated significantly fewer options than control participants and clinical apathy ratings correlated negatively with the quantity of generated options. We show that the association between measures of psychopathology and option generation is most pronounced in regard to apathy symptoms and that it is only partially mediated by deficits in verbal fluency. This study provides empirical support for dysfunctional option generation as a possible mechanism for apathy in schizophrenia. Our data emphasize the potential importance of predecisional stages in the development and persistence of apathy symptoms in neuropsychiatric disorders and might also inform the development of novel treatment options in the realm of cognitive remediation.
    Full-text · Article · Jan 2015 · Journal of Abnormal Psychology
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    ABSTRACT: There is growing evidence that reward processing is disturbed in schizophrenia. However, it is uncertain whether this dysfunction predates or is secondary to the onset of psychosis. Studying 21 unmedicated persons at risk for psychosis plus 24 healthy controls (HCs) we used a incentive delay paradigm with monetary rewards during functional magnetic resonance imaging. During processing of reward information, at-risk individuals performed similarly well to controls and recruited the same brain areas. However, while anticipating rewards, the high-risk sample exhibited additional activation in the posterior cingulate cortex, and the medio-and superior frontal gyrus, whereas no significant group differences were found after rewards were administered. Importantly, symptom dimensions were differentially associated with anticipation and outcome of the reward. Positive symptoms were correlated with the anticipation signal in the ventral striatum (VS) and the right anterior insula (rAI). Negative symptoms were inversely linked to outcome-related signal within the VS, and depressive symptoms to outcome-related signal within the medial orbitofrontal cortex (mOFC). Our findings provide evidence for a reward-associated dysregulation that can be compensated by recruitment of additional prefrontal areas. We propose that stronger activations within VS and rAI when anticipating a reward reflect abnormal processing of potential future rewards. Moreover, according to the aberrant salience theory of psychosis, this may predispose a person to positive symptoms. Additionally, we report evidence that negative and depressive symptoms are differentially associated with the receipt of a reward, which might demonstrate a broader vulnerability to motivational and affective symptoms in persons at-risk for psychosis.
    Full-text · Article · Nov 2014 · Frontiers in Behavioral Neuroscience

  • No preview · Conference Paper · Apr 2014

  • No preview · Article · Apr 2014 · Schizophrenia Research

  • No preview · Article · Apr 2014 · Schizophrenia Research

  • No preview · Article · Apr 2014 · Schizophrenia Research

  • No preview · Article · Apr 2014 · Schizophrenia Research
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    ABSTRACT: Cognitive remediation is a promising pathway for ameliorating cognitive impairment of patients with schizophrenia. Here, we investigate predictors of improvement in problem-solving ability for two different types of cognitive remediation - specific problem-solving training and training of basic cognition. For this purpose we conducted a re-analysis of a randomized controlled trial comparing these two training approaches. The main outcome measure was improvement in problem-solving performance. Correlational analyses were used to assess the contribution of clinical, cognitive and training-related predictors. In the problem-solving training group, impaired pre-training planning ability was associated with stronger improvement. In contrast, in the basic cognition training group antipsychotic medication dose emerged as a negative predictor. These results demonstrate that predictors for successful cognitive remediation depend on the specific intervention. Furthermore, our results suggest that at least in the planning domain patients with impaired performance benefit particularly from a specific intervention. (JINS, 2014, 20, 1-6).
    Full-text · Article · Mar 2014 · Journal of the International Neuropsychological Society
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    ABSTRACT: Schizophrenia is a chronic disorder, which severely limits the social and occupational functioning. Employment, education, relationships, housing and health are among the most frequently stated life and treatment goals among persons suffering from schizophrenia. Rehabilitation for persons with schizophrenia aims at preservation and improvement of psychosocial functions in areas such as work, social relationship and independent living skills, promotes recovery-oriented interventions and, therefore, serves the central goals of affected persons. Cognitive functioning, education, negative symptoms, social support and skills, age, work history, and rehabilitation service to restore community functioning have proven to be strong predictors for successful psychiatric rehabilitation. It makes sense to concentrate on these predictors when improvement of psychiatric rehabilitation is targeted. Cognitive remediation produces moderate improvements in cognitive performance and, when combined with functional training and embedded in comprehensive psychiatric rehabilitation, also enhances functional outcome. Germany provides a highly differentiated system of psychosocial support for schizophrenic patients. However, the "German disease" with different care providers being in charge in subsequent stages of recovery hampers efficient organisation of psychiatric rehabilitation. Improvement of overall organisation, i. e., configuration of interfaces, understanding of the complex interactions of measures, design of disease specific programmes, research and economic evaluation constitute major challenges in the field of psychiatric rehabilitation.
    No preview · Article · Mar 2014 · Fortschritte der Neurologie · Psychiatrie
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    ABSTRACT: Although the effects of caffeine on basic cognitive functions are well-known, its effects on more complex decision making, particularly on option generation, is yet to be explored. We examined the effects of caffeine on option generation in decision making using everyday life decisional situations. In a double-blind placebo-controlled experiment, participants (N = 47) either received 300 mg of caffeine or a placebo. Participants had to generate choice options (things they could do) for a series of high and low familiar real-world scenarios and, subsequently, to decide among these options. Analyses revealed that participants in the caffeine condition generated significantly fewer options than participants in the placebo condition. Moreover, caffeine significantly reduced the option generation onset time, that is, participants in the caffeine condition generated their first option significantly faster than participants in the placebo condition. Regarding subsequent choice, we found evidence supporting the "take-the-first" heuristic, that is, the tendency to select the first generated option. This tendency was neither affected by caffeine nor by the familiarity of the scenarios. Caffeine results in fewer options generated in unconstrained real-life decision-making situations and decreases generation onset times.
    Full-text · Article · Feb 2014 · Psychopharmacology
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    ABSTRACT: Providing care and support for individuals with severe mental illness in sheltered and supported housing facilities is frequently characterized by difficult courses, particularly if it concerns residents with "heavy user" profiles. These individuals oftentimes change their residence and are extensively hospitalized on acute psychiatric wards. To date, little is known about the needs of providers of sheltered and supported housing concerning cooperation with psychiatric hospitals and support by psychiatric services. An explorative survey was conducted among the sheltered and supported housing facilities in the canton of Zurich. A short questionnaire was distributed among all 140 institutions in written form. The responses were analyzed thematically with respect to four predefined categories. Fifty-six institutions providing 1,600 places (about 50 % of the capacity in the canton of Zurich) responded. Experiences and problems with the focus group of residents as well as causes for problematic courses are described. A sound working routine with the psychiatric hospitals was considered as a precondition for the provision of high quality housing support. The needs concerned regular and flexible cooperation with psychiatric hospitals as well as open communication in particular at discharge from the clinic and intake at the housing facility. Concentration of competencies and knowledge within psychiatric hospitals about sheltered housing institutions and their needs could improve service provision and may result in higher certitude of housing facilities. Thereby, their ability to manage patients with severe mental illness could be improved and extensive hospitalization of individuals from this group could be reduced.
    No preview · Article · Feb 2014 · Neuropsychiatrie: Klinik, Diagnostik, Therapie und Rehabilitation: Organ der Gesellschaft Österreichischer Nervenärzte und Psychiater
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    ABSTRACT: Subject: Providing care and support for individuals with severe mental illness in sheltered and supported housing facilities is frequently characterized by difficult courses, particularly if it concerns residents with “heavy user” profiles. These individuals oftentimes change their residence and are extensively hospitalized on acute psychiatric wards. To date, little is known about the needs of providers of sheltered and supported housing concerning cooperation with psychiatric hospitals and support by psychiatric services. Methods: An explorative survey was conducted among the sheltered and supported housing facilities in the canton of Zurich. A short questionnaire was distributed among all 140 institutions in written form. The responses were analyzed thematically with respect to four predefined categories. Results: Fifty-six institutions providing 1,600 places (about 50 % of the capacity in the canton of Zurich) responded. Experiences and problems with the focus group of residents as well as causes for problematic courses are described. A sound working routine with the psychiatric hospitals was considered as a precondition for the provision of high quality housing support. The needs concerned regular and flexible cooperation with psychiatric hospitals as well as open communication in particular at discharge from the clinic and intake at the housing facility. Conclusions: Concentration of competencies and knowledge within psychiatric hospitals about sheltered housing institutions and their needs could improve service provision and may result in higher certitude of housing facilities. Thereby, their ability to manage patients with severe mental illness could be improved and extensive hospitalization of individuals from this group could be reduced. Fragestellung: Die Betreuung von Personen mit schweren psychischen Erkrankungen und Charakteristika der sog. Heavy users in Wohneinrichtungen ist häufig mit Problemen verbunden. Dies kann zu wiederholten Wechseln der Wohnform sowie monatelangen Aufenthalten auf psychiatrischen Akutstationen führen. Zum psychiatrischen Versorgungsbedarf der betreuten Wohneinrichtungen und zur Zusammenarbeit mit den Kliniken ist bislang wenig bekannt. Methode: Explorative schriftliche Befragung der betreuten und begleiteten Wohneinrichtungen im Kanton Zürich zur deren Perspektive auf die Thematik anhand eines kurzen Fragenkatalogs. Thematische narrative Auswertung zu vier vorab definierten Kategorien. Resultate: 56 der 140 angeschriebenen Einrichtungen haben sich an der Befragung beteiligt. Diese Einrichtungen bieten zusammen rund 1600 Wohnplätze (50 % der gesamten Kapazität im Kanton Zürich) an. Erfahrungen mit der Betreuung der fokussierten Klientel sowie Ursachen für problematische Verläufe werden beschrieben. Voraussetzung für eine tragfähige Betreuung dieser schwierig zu betreuenden Personen ist eine gute und routinierte Zusammenarbeit mit den psychiatrischen Kliniken. Eine intensive und flexible Zusammenarbeit sowie eine transparente Kommunikation mit den psychiatrischen Kliniken, insbesondere in der Zeit unmittelbar nach Klinikentlassung und in Krisensituationen eines Bewohners sind zentrale Anliegen der betreuten Wohneinrichtungen. Schlussfolgerungen: Die Bündelung von Wissen und Kompetenzen innerhalb der Klinik über die Rahmenbedingungen der Wohneinrichtungen und deren psychiatrischen Versorgungsbedarf könnte die Versorgung an der Schnittstelle verbessern, für mehr Sicherheit für die Wohneinrichtungen sorgen und damit deren Tragfähigkeit erhöhen. Häufige und lange Aufenthalte in der Klinik könnten damit weiter reduziert werden.
    No preview · Article · Feb 2014
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    ABSTRACT: When humans and other animals make decisions in their natural environments prospective rewards have to be weighed against costs. It is well established that increasing costs lead to devaluation or discounting of reward. While our knowledge about discount functions for time and probability costs is quite advanced, little is known about how physical effort discounts reward. In the present study we compared three different models in a binary choice task in which human participants had to squeeze a handgrip to earn monetary rewards: a linear, a hyperbolic, and a parabolic model. On the group as well as the individual level, the concave parabolic model explained most variance of the choice data, thus contrasting with the typical hyperbolic discounting of reward value by delay. Research on effort discounting is not only important to basic science but also holds the potential to quantify aberrant motivational states in neuropsychiatric disorders.
    Full-text · Article · Oct 2013 · Behavioural processes
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    Annemarie Kalis · Stefan Kaiser · Andreas Mojzisch
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    ABSTRACT: Most empirical studies on decision-making start from a set of given options for action. However, in everyday life there is usually no one asking you to choose between A, B, and C. Recently, the question how people come up with options has been receiving growing attention. However, so far there has been neither a systematic attempt to define the construct of "option" nor an attempt to show why decision-making research really needs this construct. This paper aims to fill that void by developing definitions of "option" and "option generation" that can be used as a basis for decision-making research in a wide variety of decision-making settings, while clarifying how these notions relate to familiar psychological constructs. We conclude our analysis by arguing that there are indeed reasons to believe that option generation is an important and distinct aspect of human decision-making.
    Full-text · Article · Aug 2013 · Frontiers in Psychology

Publication Stats

1k Citations
190.71 Total Impact Points

Institutions

  • 2010-2014
    • University of Zurich
      • Klinik für Psychiatrie und Psychotherapie
      Zürich, Zurich, Switzerland
  • 2005-2014
    • Psychiatrische Universitätsklinik Zürich
      Zürich, Zurich, Switzerland
  • 2002-2013
    • Universität Heidelberg
      • • General Psychiatry
      • • Department of Geriatric Psychiatry
      • • Center of Psychosocial Medicine
      Heidelburg, Baden-Württemberg, Germany
  • 2008
    • evaplan at the University Hospital Heidelberg
      Heidelburg, Baden-Württemberg, Germany