I Janssen

Maastricht University, Maastricht, Provincie Limburg, Netherlands

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Publications (16)72.04 Total impact

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    ABSTRACT: Patients with psychosis display alterations in social cognition as well as in the realm of neurocognition. It is unclear, however, to what degree these cognitive domains represent two separate dimensions of liability or the pleiotropic expression of a single deficit. The purpose of the present study was to investigate (i) to what extent alterations in social cognition represent an independent area of vulnerability to psychosis, separate from neurocognitive deficits and (ii) whether social cognition is one construct or can be divided into several subcomponents. Five social cognition and three neurocognitive tasks were completed by 186 participants with different levels of vulnerability for psychosis: 44 patients with psychotic disorder; 47 subjects at familial risk; 41 subjects at psychometric risk and 54 control subjects. The social cognition tasks covered important basic subcomponents of social cognition, i.e. mentalisation (or theory of mind), data gathering bias (jumping to conclusions), source monitoring and attribution style. Neurocognitive tasks assessed speed of information processing, inhibition, cognitive shifting and strategy-driven retrieval from semantic memory. The results of factor analysis suggested that neurocognition and social cognition are two separate areas of vulnerability in psychosis. Furthermore, the social cognition measures lacked significant overlap, suggesting a multidimensional construct. Cognitive liabilities to psychosis are manifold, and include key processes underlying basic person-environment interactions in daily life, independent of cognition quantified by neuropsychological tests.
    Schizophrenia Research 09/2008; 103(1-3):257-65. · 4.59 Impact Factor
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    ABSTRACT: Failing of mentalising has been suggested to underlie certain symptoms of psychosis. An as yet unresolved issue is whether mentalising deficits reflect a characteristic which can also be detected in people at risk for psychosis or people with evidence of subclinical expression of psychosis. This study wanted to assess an aspect of mentalising in four groups with different levels of psychosis vulnerability, and to examine associations between mentalising and symptoms of psychosis. The study included i) 40 patients with psychosis, ii) 49 non-psychotic first-degree relatives (familial risk), iii) 41 subjects from the general population with a high level of positive psychotic experiences (psychometric risk) and iv) 54 healthy controls. All subjects performed the 'Hinting Task'. There was a significant association between psychosis risk and impairment on the Hinting Task (beta linear trend=0.37, p<0.001). Using the control group as the reference, the association with impairment on the Hinting Task was highest for the patient group (beta=0.46, p<0.001), whereas the familial risk group (beta=0.16, p=0.06) displayed an intermediate probability of failure. The psychometric risk group did not significantly differ from the control group (beta=0.04, p=0.653). In the patient group, impairment on the Hinting Task was associated with current hallucinations and paranoid symptoms. In the familial risk group, there was an association between the Hinting Task and paranoid symptoms. These results suggest that vulnerability to psychosis is expressed as an impairment in mentalising, which may have a mediating role in the formation of certain positive symptoms of psychosis.
    Schizophrenia Research 02/2008; 99(1-3):103-10. · 4.59 Impact Factor
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    ABSTRACT: A disorder of self-monitoring may underlie the positive symptoms of psychosis. The cognitive mechanisms associated with these symptoms may also be detectable in individuals at risk of psychosis. To investigate (a) whether patients with psychosis show impaired self-monitoring, (b) to what degree this is associated with positive symptoms, and (c) whether this is associated with liability to psychotic symptoms. The sample included: individuals with a lifetime history of non-affective psychosis (n=37), a genetically defined risk group (n=41), a psychometrically defined risk group (n=40), and control group (n=49). All participants carried out an action-recognition task. Number of action-recognition errors was associated with psychosis risk (OR linear trend over 3 levels:1.12, 95% CI1.04-1.20) and differential error rate was associated with the degree of delusional ideation in a dose-response fashion (OR linear trend over 3 levels:1.13, 95% CI1.00-1.26). Alterations in self-monitoring are associated with psychosis with evidence of specificity for delusional ideation. In the risk state, this is expressed more as failure to recognise self-generated actions, whereas in illness failure to recognise alien sources come to the fore.
    The British journal of psychiatry. Supplement 01/2008; 51:s58-62.
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    ABSTRACT: To investigate whether cognitive alterations associated with vulnerability to psychosis, are associated with expression of psychopathology and functional outcome in groups at different levels of risk for psychotic illness. Neurocognition, psychopathology and functional outcome were measured in subjects with variable risk for psychosis: i) 29 patients with psychotic disorder, ii) 46 subjects at familial risk, iii) 41 subjects at psychometric risk and iv) 54 control subjects. Dose-response relationships between cognitive dysfunction and increasing risk for psychosis were found. Cognitive alterations were predicted by negative symptoms in patients and by positive psychotic experiences in the familial risk group. In both at risk groups, cognitive speed was associated with functional outcome. Some cognitive impairments serve as neutral endophenotypic marker across the psychosis continuum. However, other cognitive alterations associated with transmission of psychosis may have a direct impact on the pathway from risk to psychopathology and alterations in functioning.
    Acta Psychiatrica Scandinavica 11/2007; 116(4):253-62. · 4.86 Impact Factor
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    ABSTRACT: Current cognitive models of positive symptoms of psychosis suggest a mechanism of defective self-monitoring that may be relevant for (i) expression of psychosis at the clinical and subclinical level and (ii) transmission of risk for psychosis. The study included 41 patients with psychosis, 39 non-psychotic first-degree relatives, 39 subjects from the general population with a high level of positive psychotic experiences, and 52 healthy controls with an average level of positive psychotic experiences. All subjects performed a speech attribution task in which single adjectives with a complimentary or derogatory meaning were presented to them on a computer screen; subjects had to read aloud and determine the source (self/other/uncertain) of the words they heard. In some of the trials, participants' speech was distorted, in others they heard someone else's voice (alien feedback condition) that could also be distorted. No large or significant differences in errors in the speech attribution task were found between the four groups in any of the conditions. Contrary to previous work using this paradigm, this study found no evidence that either expression of psychosis or risk for psychosis was associated with impairment in self-monitoring.
    Psychological Medicine 05/2007; 37(4):569-76. · 5.59 Impact Factor
  • Schizophrenia Research 10/2006; 86. · 4.59 Impact Factor
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    ABSTRACT: The aims of the study were to investigate whether (i) patients with lifetime presence of non-affective psychosis show an external-personal attribution bias for negative events, (ii) this attribution style can also be detected in first-degree relatives of patients with psychosis and subjects with subclinical psychotic experiences, and (iii) this attribution style is related to the presence of psychotic symptoms, in particular delusions. Participants were 23 patients with lifetime presence of non-affective psychosis, a high- risk group of 36 first-degree relatives of patients with non-affective psychosis, a high-risk group of 31 subjects with subclinical psychotic experiences and 46 normal controls. Attribution style was measured by the Internal, Personal and Situational Attribution Questionnaire. Positive symptoms were assessed with the Present State Examination (PSE) and the Scale for the Assessment of Positive Symptoms (SAPS). Relative to the controls, an externalizing bias was apparent in the patient group (beta = 0.20, p = 0.03) but not in the two high-risk groups. There was a dose-response association between externalizing bias and the delusions subscale of the PSE (relative to lowest level: highest level of delusions: beta = 0.53, p = 0.04; intermediate levels of delusions: beta = 0.23, p = 0.35). No significant differences were found in personalizing bias between the four groups. Patients with psychosis tend to use an externalizing bias in their explanations of negative social events, and this bias is associated with the presence of positive psychotic symptoms, in particular delusions. A deviant attribution style is not part of the vulnerability to psychosis.
    Psychological Medicine 07/2006; 36(6):771-8. · 5.59 Impact Factor
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    ABSTRACT: This study examined whether the probabilistic reasoning bias referred to as a "jumping-to-conclusions" (JTC) style of reasoning, which, according to previous research, is associated with particular psychotic symptoms such as delusions, represents a trait that can also be detected in nonpsychotic relatives of patients with schizophrenia and in nonpsychotic individuals with a high level of psychotic experiences. Participants were, in order of level of psychosis liability, 40 patients with schizophrenia or a schizoaffective disorder, 40 first-degree nonpsychotic relatives, 41 participants from the general population with above average expression of psychotic experiences, and 53 participants from the general population with an average level of psychotic experiences. A "jumping-to-conclusions" bias was assessed using the beads task. A dose-response relationship was found in the association between level of psychosis liability and JTC (defined as needing only a single bead to complete the beads task) (odds ratio [OR] linear trend = 1.59, 95% CI: 1.13-2.24), and, independently, alinear association was apparent between JTC and level of delusional ideation (OR linear trend = 2.59, 95% CI: 1.18-5.69). In addition, the association between psychosis liability and JTC was generally much stronger as the level of delusional ideation was higher. JTC is associated with liability to psychosis (trait), in particular if the psychosis phenotype is characterized by delusional ideation (state).
    Schizophrenia Bulletin 05/2006; 32(2):341-51. · 8.49 Impact Factor
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    ABSTRACT: Exposure to early trauma may increase the risk of dysfunctional responses to anomalous psychotic experiences resulting in psychotic symptom formation. In a three-wave longitudinal general population study, 4045 never-psychotic individuals exposed and non-exposed to trauma before the age of 16 years, according to baseline interview were interviewed for the onset of psychotic experiences 3 years later (T2). In 36 individuals with incident psychosis at T2, assessments were made, for each psychotic experience, of i) the amount of distress associated with and ii) the degree of coping and subjective control over the experience. In the 16 observations of an incident psychotic experience, in the absence of distress, the baseline rate of early trauma was low (6%), whereas it was much higher in the 21 observations of an incident psychotic experience with distress [43%; odds ratio=10.0, 95% confidence interval (CI): 1.04, 96.3; P=0.046]. Similarly, coping attempts in the context of early trauma was associated with less control (reduction of 2 points on a seven-point scale, 95% CI: -4.0, -0.07). Early experience of trauma may create lasting cognitive and affective vulnerabilities to develop clinical symptoms arising out of early, non-clinical psychotic experiences.
    Acta Psychiatrica Scandinavica 12/2005; 112(5):360-6. · 4.86 Impact Factor
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    ABSTRACT: It was investigated whether the reported association between representations of parental rearing style and psychosis does not represent a main effect, but instead is a proxy indicator of the true underlying risk factor of early trauma. In a general population sample of 4045 individuals aged 18-64 years, first ever onset of positive psychotic symptoms at 3-year follow-up was assessed using the Composite International Diagnostic Interview and clinical interviews if indicated. Representations of parental rearing style were measured with the Parental Bonding Instrument (PBI). Lower baseline level of PBI parental care predicted onset of psychotic symptoms 2 years later. However, when trauma was included in the equation, a strong main effect of trauma emerged at the expense of the effect size of PBI low care. The results suggest that associations between representations of parental rearing style and psychosis may be an indicator of the effect of earlier exposure to childhood trauma.
    Acta Psychiatrica Scandinavica 12/2005; 112(5):372-5. · 4.86 Impact Factor
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    ABSTRACT: To examine the hypothesis that individuals from the general population who report childhood abuse are at increased risk of developing positive psychotic symptoms. Data were derived from a general population sample of 4045 subjects aged 18-64 years. First ever onset of positive psychotic symptoms at 2-year follow-up were assessed using the Composite International Diagnostic Interview and additional clinical interviews if necessary. Childhood abuse was assessed at baseline. Baseline reported childhood abuse predicted development of positive psychotic symptoms associated with need for care [odds ratio (OR) = 11.5, 95% CI 2.6-51.6]. This association remained after adjustment for demographic variables, reported risk factors and presence of any lifetime psychiatric diagnosis at baseline (OR = 7.3, 95% CI 1.1-49.0). The results suggest that early childhood trauma increases the risk for positive psychotic symptoms. This finding fits well with recent models that suggest that early adversities may lead to psychological and biological changes that increase psychosis vulnerability.
    Acta Psychiatrica Scandinavica 02/2004; 109(1):38-45. · 4.86 Impact Factor
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    ABSTRACT: It has been proposed that alterations in theory of mind underlie specific symptoms of psychosis. The present study examined whether alterations in theory of mind reflect a trait that can be detected in non-psychotic relatives of patients with schizophrenia. Participants were 43 patients with schizophrenia or schizoaffective disorder, 41 first-degree non-psychotic relatives and 43 controls from the general population. Theory of mind was assessed using a hinting task and a false-belief task. There was a significant association between schizophrenia risk and failure on the hinting task (OR linear trend = 2.01, 95% CI: 1.22-3.31), with relatives having intermediate values between patients and controls. Adjustment for IQ and neuropsychological factors reduced the association by small amounts. The association between schizophrenia risk and failure on the false-belief tasks was not significant. Changes in theory of mind are associated with schizophrenia liability. General cognitive ability and neuropsychological measures seem to mediate only part of this association.
    Acta Psychiatrica Scandinavica 09/2003; 108(2):110-7. · 4.86 Impact Factor
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    ABSTRACT: In the UK and The Netherlands, people with high rates of psychosis are chronically exposed to discrimination. To test whether perceived discrimination is associated longitudinally with onset of psychosis. A 3-year prospective study of cohorts with no history of psychosis and differential rates of reported discrimination on the basis of age, gender, disability, appearance, skin colour or ethnicity and sexual orientation was conducted in the Dutch general population (n=4076). The main outcome was onset of psychotic symptoms (delusions and hallucinations). The rate of delusional ideation was 0.5% (n=19) in those who did not report discrimination, 0.9% (n=4) in those who reported discrimination in one domain, and 2.7% (n=3) in those who reported discrimination in more than one domain (exact P=0.027). This association remained after adjustment for possible confounders. No association was found between baseline discrimination and onset of hallucinatory experiences. Perceived discrimination may induce delusional ideation and thus contribute to the high observed rates of psychotic disorder in exposed minority populations.
    The British Journal of Psychiatry 02/2003; 182:71-6. · 6.61 Impact Factor
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    ABSTRACT: Not all individuals with experience of psychosis develop need for care. 7076 general population individuals were studied for 3 years. 47 individuals experienced psychosis with no previous diagnosis of psychotic disorder. They were interviewed by telephone. Need for care was associated with severity of psychotic experiences rather than distress or total level of coping used. Also, individuals with need for care more often resorted to symptomatic coping style (giving in to symptoms; OR=6.07, 95% CI: 1.94, 18.95), which was associated with less perceived control (OR=0.79, 95% CI: 0.63, 0.98). Any type of coping was associated with level of distress, severity of hallucinations and presence of suspiciousness in both groups, but suspiciousness was larger in those in need for care (OR=2.27, 95% CI: 1.33, 3.87). A symptomatic coping style predicts decreased experience of control and results in need for care. Attribution of locus ofcontrol and a more submissive style vis à vis the psychotic experience may contribute to becoming a mental health patient.
    Acta Psychiatrica Scandinavica 09/2002; 106(s413). · 4.86 Impact Factor
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    ABSTRACT: Low self-esteem and high neuroticism are common features in psychosis, but in the absence of longitudinal studies it is unclear whether they represent consequences of the illness or risk factors acting before illness onset. A population sample of 3,929 individuals with no lifetime evidence of psychosis were interviewed with the Composite International Diagnostic Interview and were administered the Groningen Neuroticism Scale and the Rosenberg Self-Esteem Scale at baseline and 1 and 3 years later. At year 3, individuals with CIDI evidence of psychotic symptoms were interviewed by clinicians to identify incident psychotic or psychosis-like symptoms. Baseline neuroticism and self-esteem predicted first-ever onset of psychotic symptoms at year 3 (neuroticism, OR 1.16, 95% CI 1.09, 1.23; self-esteem, OR 1.09, 95% CI 1.01, 1.18).When adjusted for each other and for level of anxiety and depression, neuroticism was the strongest independent predictor for onset of psychotic symptoms (OR 1.16, 95% CI 1.07, 1.26). Neuroticism increases the risk for development of psychotic symptoms. Mechanisms of risk may involve certain cognitive styles associated with neuroticism, such as beliefs about the uncontrollability of certain events and experiences. The association between low self-esteem and psychosis may involve the area of overlap between self-esteem and neuroticism.
    Social Psychiatry and Psychiatric Epidemiology 02/2002; 37(1):1-6. · 2.86 Impact Factor
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