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Biomedical subjects

R J van den Bosch

Publications and source records attributed to R J van den Bosch.

At least 19 recordsLinked to original sources
PubMed2006

Sustained and transient attention in the continuous performance task.

One of the most frequently applied methods to study abnormal cognition is the Continuous Performance Task (CPT). It is unclear, however, which cognitive functions are engaged in normal CPT performance. The aims of the present study were to identify the neurocognitive functions engaged in the main variants of the CPT and to determine to what extent these variants differentially engage these functions. We hypothesized that the main CPT versions (CPT-X, CPT-AX, CPT-Identical Pairs) can be distinguished by whether they demand sustained or transient attention and sustained or transient response preparation. Transient attention to objects like letters or digits, that is, the need to switch attention to different objects from trial to trial, impairs target detection accuracy relative to sustained attention to a single object. Transient response preparation, that is, the possibility to switch response preparation on and off from trial to trial, improves response speed relative to having to sustain response preparation across all trials. Comparison of task performance and Event-Related brain Potentials (ERPs) of healthy participants obtained in the main CPT variants confirmed these hypotheses. Behavioral and ERP measures indicated worse target detection in the CPT-AX than in the CPT-X, consistent with a higher demand on transient attention in that task. In contrast, behavioral and ERP measures indicated higher response speed in the CPT-AX than in the CPT-X, associated with more response preparation in advance of the targets. This supports the idea of increased transient response preparation in the CPT-AX. We conclude that CPTs differ along at least two task variables that each influences a different cognitive function.

Adult↗
PubMed2005

Paraprofessionals for anxiety and depressive disorders.

BACKGROUND: The established mental health care system does not have the resources to meet the extensive need for care of those with anxiety and depressive disorders. Paraprofessionals partially replacing professionals may be cost-effective. OBJECTIVES: To investigate the effectiveness of any kind of psychological treatment for anxiety and depressive disorders performed by paraprofessionals compared with professionals, waiting list or placebo condition. To examine whether the results apply to clinically significant anxiety and depressive disorders of referred patients with a psychiatric history and/or whose illness has lasted two years or more. SEARCH STRATEGY: CCDANCTR-Studies using the following terms: (paraprofessional* or para-professional* or non-professional* or non-professional* or peer or volunt*); EMBASE (ExerptaMedica), MEDLINE and PsycINFO, all years published, key words: para-/paraprofessional, non-/nonprofessional, rand*, respectively psy*; citation lists of articles reviewing the subject and included studies; correspondence with authors of controlled studies and review reports on the subject. SELECTION CRITERIA: Randomised controlled trials that used symptom measures, and compared the effects of psychological treatments given by paraprofessionals (mental health care workers, paid or voluntary, unqualified with respect to the psychological treatment) with psychological treatments given by professionals, and with waiting list or placebo condition. DATA COLLECTION AND ANALYSIS: The standard mean difference was used to pool continuous data from each trial, and odds ratios were used to pool dichotomous data, using a random effects model. The generic inverse variance method was used for combining continuous and dichotomous data. The effect of low quality studies and the use of self-rated versus observer-rated measures were tested, and subgroup analyses were performed for differences between depression and anxiety diagnosis, paraprofessionals with/without professional background, group/individual intervention, length of follow-up and gender (post-hoc subgroup analysis). MAIN RESULTS: Five studies, all using self-report measures, reported five comparisons of paraprofessionals versus professionals (n=106) and five comparisons of paraprofessionals versus control condition (n=220). No differences were found between paraprofessionals and professionals (SMD=0.09, 95% CI -0.23 to 0.40, p=0.58; no significant heterogeneity). Studies comparing paraprofessionals versus control reported mixed continuous and dichotomous data showed a significant pooled effect in favour of paraprofessionals (OR=0.34, 95% CI 0.13 to 0.88, p=0.03), but heterogeneity was indicated (I(2)=60.9%, Chi(2)= 10.24, df=4, p=0.04). After correction for heterogeneity and removing one study of low quality, the pooling of data from three studies (n=128; mixed gender and women only) indicated no significant difference in effect between paraprofessionals and professionals (SMD=0.13, 95% CI -0.39 to 0.64; p=0.63) and a strongly significant pooled effect for three studies (n=188; women only) favouring paraprofessionals over the control condition (OR=0.30, 95% CI 0.18 to 0.48, p<0.00001), and homogeneity indicated between studies (I(2)=0%, Chi(2)=0.47, df=2, p=0.79). AUTHORS' CONCLUSIONS: The few studies included in the review did not allow conclusions about the effect of paraprofessionals compared to professionals. Pooling data from three studies, involving women only, indicated a significant effect for paraprofessionals (all volunteers) compared to no treatment. The evidence to date may justify the development and evaluation of programs incorporating paraprofessionals in treatment programs for anxiety and depressive disorders.

Allied Health Personnel↗
PubMed2003

What are the effects of antipsychotics on sexual dysfunctions and endocrine functioning?

The literature is reviewed and preliminary results of new studies are presented showing that treatment with classical antipsychotics, as well as risperidone, induces sexual dysfunctions in 30-60% of the patients. These antipsychotics also frequently induce amenorrhoea and galactorrhoea. Although comparative studies are rare, it is likely that prolactin-sparing antipsychotics, as recently shown in a randomized trial of olanzapine versus risperidone, induce less sexual side effects.From these studies, it becomes apparent that prolactin elevation induced by classical antipsychotics and risperidone is probably a factor in inducing sexual dysfunctions, amenorrhoea and galactorrhoea. The role of other factors inducing sexual dysfunctions like sedation, proportional, variant -blockade, testosterone, dopamine, and serotonin is discussed. Finally, it is concluded that sexual and hormonal effects of antipsychotics, although clearly important, are often neglected in research as in clinical practice. Lowering the dosage or switching to a prolactin-sparing antipsychotic often reduces sexual side effects, amenorrhoea, and galactorrhoea.

Adult↗
PubMed2001

Does frontal normality exist in schizophrenia? A saccadic eye movement study.

Many observations have supported the general idea of impaired frontal function in schizophrenia. In particular, neuropsychological studies have shown severe frontal deficits. However, other studies found normal cognitive function in a proportion of patients. Since saccadic tasks also provide an index of frontal function, we examined the presence of frontal deficits in patients by means of both neuropsychological and saccadic tasks, and compared the sensitivity of both approaches for frontal impairment. In addition, we examined the relationship between saccadic and neuropsychological measures. Twenty-four schizophrenic patients and twenty healthy controls completed an extensive neuropsychological battery and three saccadic tasks. Based on the neuropsychological battery alone, 42% of the patients showed frontal deficits, whereas combined use of neuropsychological and saccadic tasks resulted in 79% with frontal deficits. The antisaccade task appeared able to detect frontal deficits in patients who were without frontal impairment on the neuropsychological battery. Saccadic deficits were, however, not necessarily accompanied by deficits on frontal neuropsychological measures. This suggests that the saccadic and neuropsychological tasks used in the present study targeted different frontal functions. This view was supported by the lack of correlations between saccadic and frontal neuropsychological measures.

Adult↗
PubMed2001

Reasoning about the optimal duration of prophylactic antipsychotic medication in schizophrenia: evidence and arguments.

OBJECTIVE: To review evidence-based literature regarding the necessary duration of antipsychotic relapse prevention in schizophrenia and related psychoses. METHOD: A computerized search was performed on Medline, Embase Psychiatry and PsycLIT which covered the period 1974-99. We also used cross-references. RESULTS: Although schizophrenia refers mainly to an intrinsic biological vulnerability, only maintenance studies with a follow-up of 2 years at most are available. Relapses appear unpredictable and occur even after long-term successful remission during antipsychotic treatment. CONCLUSION: Since rehabilitation efforts have effects only after long-term endeavours, antipsychotic relapse prevention should be maintained for long periods. It is reasonable to treat patients suffering from schizophrenia and related psychoses for longer periods than indicated by the current guidelines.

Antipsychotic Agents↗
PubMed2000

The specificity of neurological signs in schizophrenia: a review.

This review examines the extent to which neurological signs are more prevalent in schizophrenia patients, compared to mood-disorder patients and healthy subjects, and whether there is a pattern in any of the differences that may be found. We included 17 studies and calculated the weighted mean prevalence of 30 neurological signs. The prevalence of most signs appears to be significantly different between schizophrenia patients and normal controls, but there are fewer differences between schizophrenia and mood-disorder patients. Several signs - poor stereognosis and rhythm tapping - are even more prevalent in mood-disorder patients than in schizophrenia patients. Only lack of extinction, dysdiadochokinesia, poor tandem walk, finger-thumb-opposition and articulation are significantly more prevalent in schizophrenia compared to mood-disorder patients. Impaired motor coordination seems most specific to schizophrenia. The discriminating power of motor sequencing still needs to be studied. So far, there is no evidence of a clearly interpretable pattern of neurological signs distinguishing schizophrenia patients from mood-disorder patients.

Bipolar Disorder↗
PubMed2000

Distress attributed to negative symptoms in schizophrenia.

The purpose of the study was to examine (1) to which negative symptoms schizophrenia patients attribute distress and (2) whether clinical variables can predict the levels of reported distress. With the help of a research assistant, 86 hospitalized patients completed a self-rating scale for negative symptoms. The 21 items of the self-rating scale were taken from the Scale for the Assessment of Negative Symptoms (SANS). A psychiatrist rated the patients on a number of scales, including the SANS. When patients reported particular symptoms, they were asked whether those symptoms bothered or distressed them. Answers to this question were highly dependent on the type of symptom involved. Distress was most often attributed to symptoms in the subscale avolition-apathy. Patients were also asked how much they were bothered or distressed. Again, high levels of distress were most often attributed to items in the subscale avolition-apathy. A summary score was developed for the level of reported distress: the distress score. Regression analysis showed that distress scores were not associated with the observed severity of negative symptoms or with the level of psychiatric disability. High distress scores were best predicted by the combination of high scores for depression and high scores for insight into positive symptomatology. However, this model explained only a quarter of the variance in distress scores.

Adult↗
PubMed1998

Causal mechanisms of subjective cognitive dysfunction in schizophrenic and depressed patients.

We examined causal mechanisms of subjective cognitive (dis)abilities in schizophrenic and depressed patients, and in patient and normal control groups. This exploratory study included objective cognitive performance (Continuous Performance Task) as well as mood and mental effort ratings. Self-report of cognitive dysfunction in patients was not correlated with objective cognitive deficits. Correlational patterns differed between groups. Our findings in schizophrenic and depressed patients point to different causal mechanisms of their subjective cognitive malaise, despite similar subjective ratings. Depressed patients associate high mental effort during task performance with a reduced cognitive efficacy, whereas schizophrenic patients associate high effort with cognitive symptoms like distractibility and overload.

Adult↗
PubMed1998

Experience of negative symptoms: comparison of schizophrenic patients to patients with a depressive disorder and to normal subjects.

OBJECTIVE: Three hypotheses were tested: 1) schizophrenic patients would report more impairments on a self-rating scale for negative symptoms than normal subjects and attribute higher levels of distress to these impairments, 2) schizophrenic patients would report fewer impairments than patients with a depressive disorder and attribute lower levels of distress to these impairments, and 3) schizophrenic patients would attribute their impairments less often to mental illness than would patients with a depressive disorder. METHOD: A self-rating scale for negative symptoms was administered to 86 patients with schizophrenia, 20 patients with a depressive disorder, and 33 normal subjects. The scale items were derived from the Scale for the Assessment of Negative Symptoms (SANS). Two psychiatrists also rated all of the patients on the SANS. RESULTS: The hypotheses were supported. The differences between the two groups of patients in the rates of reported impairments and the levels of reported distress remained statistically significant after control for differences in age, sex, length of current admission, length of illness, dose of neuroleptic medication, use of clozapine, and severity of negative symptoms. CONCLUSIONS: The results suggest that a large number of schizophrenic patients are somewhat aware of negative symptoms but that they are less aware of these impairments and less concerned about them than are patients with a depressive disorder.

Adolescent↗
PubMed1996

Expressed emotion on long-stay wards.

We examined the influence of an educational programme on nurses' level of expressed emotion (EE), on ward climate and on social functioning and psychopathology of hospitalized schizophrenic patients. Nurses and patients were from long-stay wards of six Dutch psychiatric hospitals. Despite an increase of nurses' knowledge about schizophrenia we did not find measurable effects on nurses' levels of EE. According to the five minute speech sample method, a third of the nurses participating in this study had a high level of expressed emotion, mainly consisting of criticism. This was a rather stable pattern. Patients, however, were reluctant to give their nurses high EE ratings on the level of expressed emotion scale. Psychopathology was not influenced by the educational programme, but social functioning of patients was related to EE in nurses. Moreover, we found a significant decline in the number of restrictive ward rules at follow-up. We conclude that, while it may be difficult to detect changes in EE level after an educational programme for nurses, there nevertheless appear to be measurable benefits for patients.

Adult↗
PubMed1996

What determines continuous performance task performance?

The Continuous Performance Task (CPT) is widely used as an indicator of cognitive dysfunction in schizophrenia. It is still unclear, however, exactly what this test measures. We examined the contribution of motor speed, reaction time measures, mental effort, and level of psychopathology to the performance on a double-stimulus CPT. This study included schizophrenia patient groups, depressive patient groups, and patient and normal control groups. Subjects were retested twice: once after 1 week and again at 3 months. In patients with schizophrenia or depression, the sensitivity measure (d') was strongly and consistently associated with motor speed and with the standard deviation of reaction times (response variability) to target stimuli. The association with response variability was also found at followup tests in the control groups. We conclude that in patients with schizophrenia or depression, the sensitivity measure of a double-stimulus CPT is associated with cognitive mechanisms that determine motor proficiency and response variability.

Adult↗
PubMed1995

The multidimensionality of schizotypy.

We present an overview of self-report scales for measuring schizotypy and a review of factor-analytical studies of these scales. These studies show that schizotypy is a multidimensional construct consisting of three or four factors. Positive Schizotypy, Negative Schizotypy, Nonconformity, and possibly Social Anxiety/Cognitive Disorganization. Clinical and external validation studies provide support for the construct validity of the Positive Schizotypy and Negative Schizotypy factors, but as yet fail to support the Nonconformity and Social Anxiety/Cognitive Disorganization factors. In accordance with this multidimensional structure, the scales for measuring schizotypy can be classified as factor-specific scales. We consider the striking similarities between the multidimensionality of schizotypal traits and the multidimensionality of schizophrenic symptoms. We also look at the similarities and differences between schizotypy and normal personality traits. Some practical and theoretical implications of these relationships are discussed.

Diagnosis, Differential↗
PubMed1988

Subjective cognitive dysfunction, eye tracking, and slow brain potentials in schizophrenic and schizoaffective patients.

The relationships between subjective cognitive dysfunction (so-called basic symptoms) and some psychophysiological measures were examined repeatedly in schizophrenic and schizoaffective patients during an acute psychotic episode, and comparisons were made with psychotic symptom ratings. Psychophysiological variables were: quality of eye tracking, amplitude measures of the contingent negative variation, and reaction time. Ratings of psychotic and basic symptoms were significantly correlated, but only the basic symptom score showed significant associations with eye tracking, contingent negative variation, and reaction time. Although this pattern was confined to the recovery phase of the psychotic episode, the results suggest that the core psychopathological correlates of these psychophysiological measures consist of basic symptoms rather than florid psychotic symptoms.

Adult↗
PubMed1988

Slow potential correlates of frontal function, psychosis, and negative symptoms.

The contingent negative variation (CNV) was used to study cortical activation in frontal and central areas in psychotic and nonpsychotic patients. Psychotic patients showed a higher frontal relative to central CNV amplitude than nonpsychotic patients, a finding that was correlated with performance on a test of frontal function. Negative symptom ratings (physical anhedonia and social closeness) were correlated with relatively low frontal versus central CNV amplitude, but only in psychotic patients.

Adult↗