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Lydia Krabbendam

Publications and source records attributed to Lydia Krabbendam.

30 records · Page 2Linked to original sources
PubMed2005

The schizophrenia envirome.

PURPOSE OF REVIEW: To show which aspects of the environment increase the risk for schizophrenia and how they interact with pre-existing liability for psychosis. RECENT FINDINGS: Not only does cannabis survive as a risk factor for psychosis, but the evidence is showing concrete synergistic effects between cannabis and pre-existing liability to psychosis. The urban environment is, in terms of attributable risk, the most important proxy environmental risk factor. There is evidence that it interacts with genetic risk and it has been hypothesized that the mechanism involves the cumulative effects of altered social interactions at the individual level and possibly also at the level of the wider social environment, such as the neighbourhood. Early trauma is another aspect of the environment that has recently been linked prospectively to psychosis, and meta-analytic work demonstrates conclusively that minority status is a risk factor, part of which may be mediated by chronic exposure to discrimination. Prenatal environmental effects may involve folate or vitamin D deficiency, viral infections or adverse effects associated with low or high birth weight. The mechanism by which the environment is likely to impact on risk is through cognitive and emotional pathways on the one hand, and biological pathways, possibly involving dopamine sensitization, on the other. SUMMARY: Several synergistic mechanisms involving proxy measures of genes and proxy measures of the environment, such as gene-cannabis, gene-urbanicity and gene-stress interactions, offer concrete avenues to pursue research that stands a good chance of elucidating at least some of the causes of schizophrenia.

Journal Article↗
PubMed2005

The impact of maternal stress on pregnancy outcome in a well-educated Caucasian population.

The aim of the study was to examine the association between stress and pregnancy outcome after adjustment for possible confounding and mediating variables. A prospective cohort study of 5511 pregnancies was conducted in 2001-03 in the Netherlands. A standardised questionnaire collecting demographics and mental health data was administered at 14 and 30 weeks of pregnancy. Medical data on the pregnancy and delivery were obtained from obstetricians and midwives. The results showed that a high level of perceived stress at 14 weeks of pregnancy increased the risk for delivery of an infant that was small-for-gestational-age (OR = 1.26 [95% CI 1.01, 1.56]), but the association was reduced after adjustment for the possible confounding effects of demographic variables (OR = 1.16 [95% CI 0.92, 1.47]). The results do not support a direct relationship between perceived stress and adverse pregnancy outcome. Demographic variables may explain the association between psychosocial stress and pregnancy outcome to a significant degree.

Adult↗
PubMed2005

Role of distress in delusion formation.

BACKGROUND: Contemporary cognitive psychological theories suggest that distress plays a mediating role in delusion formation. AIMS: To study the amplifying role of distress from early perceptual intrusions to delusion formation. METHOD: A general population sample of 7076 individuals was interviewed with the Composite International Diagnostic Interview (CIDI) in 1996 (baseline), 1997 (T1) and 1999 (T2). At T2, clinicians also scored the Brief Psychiatric Rating Scale (BPRS) item "unusual thought content". Analyses compared hallucinatory experiences with and without subjective distress at baseline for risk of delusion formation at follow-up. RESULTS: Individuals experiencing hallucinations with distress, compared with those without distress had a fourfold increased risk of subsequent delusion formation. CONCLUSIONS: This finding corroborates the hypothesis that distress associated with early perceptual intrusions serves as a catalyst in the development of delusions.

Adolescent↗
PubMed2005

Development of depressed mood predicts onset of psychotic disorder in individuals who report hallucinatory experiences.

OBJECTIVES: Current psychological theories state that the clinical outcome of hallucinatory experiences is dependent on the degree of associated distress, anxiety, and depression. This study examined the hypothesis that the risk for onset of psychotic disorder in individuals with self-reported hallucinatory experiences would be higher in those who subsequently developed depressed mood than in those who did not. DESIGN: A prospective cohort study of a general population sample. METHODS: A sample of 4,670 individuals with no lifetime evidence of any psychotic disorder were interviewed with the Composite International Diagnostic Interview Schedule (CIDI) at baseline and 1 and 3 years later. At Year 3, individuals with CIDI evidence of psychotic symptoms were interviewed by clinicians to identify potential onset of psychotic disorder. Psychotic disorder was specified at three levels; two involving severity of positive symptoms of psychosis, and one using additional clinical judgment of need for care. RESULTS: Given the presence of hallucinatory experiences at baseline, the increase in risk of having the psychosis outcome at Year 3 was higher in the group with depressed mood at Year 1 than in the group without depressed mood at Year 1 (any level of psychotic symptoms: risk difference 17.0%, 95% CI - 1.7, 35.7; severe level of psychotic symptoms: risk difference 21.7%, 95% CI 3.2, 40.2; needs-based diagnosis of psychotic disorder: risk difference 16.8%, 95% CI 0.4, 33.3). CONCLUSION: The results are in line with current psychological models of psychosis that emphasize the role of secondary appraisals of psychotic experiences in the onset of clinical disorder.

Adult↗
PubMed2004

Prospective cohort study of cannabis use, predisposition for psychosis, and psychotic symptoms in young people.

OBJECTIVE: To investigate the relation between cannabis use and psychotic symptoms in individuals with above average predisposition for psychosis who first used cannabis during adolescence. DESIGN: Analysis of prospective data from a population based sample. Assessment of substance use, predisposition for psychosis, and psychotic symptoms was based on standardised personal interviews at baseline and at follow up four years later. PARTICIPANTS: 2437 young people (aged 14 to 24 years) with and without predisposition for psychosis. MAIN OUTCOME MEASURE: Psychotic symptoms at follow up as a function of cannabis use and predisposition for psychosis at baseline. RESULTS: After adjustment for age, sex, socioeconomic status, urbanicity, childhood trauma, predisposition for psychosis at baseline, and use of other drugs, tobacco, and alcohol, cannabis use at baseline increased the cumulative incidence of psychotic symptoms at follow up four years later (adjusted odds ratio 1.67, 95% confidence interval 1.13 to 2.46). The effect of cannabis use was much stronger in those with any predisposition for psychosis at baseline (23.8% adjusted difference in risk, 95% confidence interval 7.9 to 39.7, P = 0.003) than in those without (5.6%, 0.4 to 10.8, P = 0.033). The risk difference in the "predisposition" group was significantly greater than the risk difference in the "no predisposition" group (test for interaction 18.2%, 1.6 to 34.8, P = 0.032). There was a dose-response relation with increasing frequency of cannabis use. Predisposition for psychosis at baseline did not significantly predict cannabis use four years later (adjusted odds ratio 1.42, 95% confidence interval 0.88 to 2.31). CONCLUSION: Cannabis use moderately increases the risk of psychotic symptoms in young people but has a much stronger effect in those with evidence of predisposition for psychosis.

Adolescent↗
PubMed2003

Sex differences in symptoms of psychosis in a non-selected, general population sample.

BACKGROUND: Little is known about sex differences in psychosis beyond the borders of clinical disorder. METHODS: A general population sample of 7,076 subjects was assessed using the Composite International Diagnostic Interview, in order to explore sex differences in the prevalence of any positive and negative symptoms of psychosis, and to examine to what degree any differences could be explained by differences in level of affective symptoms. RESULTS: Male sex was associated with higher prevalence of negative symptoms (OR = 1.6, 95% CI = 1.0, 2.5), independent of differences in affective symptoms and presence of DSM-III-R psychotic disorder. Women had higher rates of positive psychotic experiences (OR = 0.8, 95% CI = 0.7, 0.9), but this difference disappeared after adjustment for depressive symptoms (adjusted OR = 1.2, 95% CI = 0.9, 1.5). CONCLUSION: The sex differences in psychopathology that are seen in schizophrenia are expressed beyond the clinical phenotype, suggesting sex-dependent continuous and normal variation of several psychosis dimensions. The higher rates of positive psychotic experiences seen in women may be secondary to differences in the rate of affective symptoms.

Adult↗
PubMed2003

Sex differences in psychosis: normal or pathological?

BACKGROUND: Schizophrenia first appears in adolescence, in boys at an earlier age than girls. The interpretation of this key epidemiological finding crucially depends on whether similar age-related sex differences exist in the expression of associated, subclinical psychosis-like experiences. METHODS: Findings are based on a population sample of 2548 adolescents and young adults aged 17-28. Subjects were assessed with the core psychosis sections on delusions and hallucinations of the Munich-Composite International Diagnostic Interview. RESULTS: The risk of subclinical psychotic experiences was significantly higher for males in the younger half of the cohort (17-21 years), but similar in the older half (22-28 years). CONCLUSIONS: These findings suggest that normal maturational changes in adolescence with differential age of onset in boys and girls cause the expression of psychosis, the extreme of which is schizophrenia.

Adolescent↗
PubMed2003

Cognitive rehabilitation in schizophrenia: a quantitative analysis of controlled studies.

RATIONALE: Cognitive rehabilitation is now recognized as an important tool in the treatment of schizophrenia, and findings in this area are emerging rapidly. There is a need for a systematic review of the effects of the different training programs. OBJECTIVES: To review quantitatively the controlled studies on cognitive rehabilitation in schizophrenia for the effect of training on performance on tasks other than those practiced in the training procedure. METHODS: A meta-analysis was conducted on 12 controlled studies of cognitive rehabilitation in schizophrenia taking into account the effects of type of rehabilitation approach (rehearsal or strategy learning) and duration of training. RESULTS: The mean weighted effect size was 0.45, with a 95% confidence interval from 0.26 to 0.64. Effect sizes differed slightly, depending on rehabilitation approach, in favor of strategy learning, but this difference did not reach statistical significance. Duration of training did not influence effect size. CONCLUSIONS: Cognitive rehabilitation can improve task performance in patients with schizophrenia and this effect is apparent on tasks outside those practiced during the training procedure. Future studies should include more real-world outcomes and perform longitudinal evaluations.

Brief Psychiatric Rating Scale↗
PubMed2002

Neuroticism and low self-esteem as risk factors for psychosis.

BACKGROUND: 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. METHODS: 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. RESULTS: 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). CONCLUSIONS: 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.

Adult↗
PubMed2002

Are cognitive impairments associated with sensitivity to stress in schizophrenia? An experience sampling study.

OBJECTIVE: Patients with a diagnosis of schizophrenia display cognitive impairments and abnormal sensitivity to stress. However, little is known about the relationship between these two endophenotypes. METHOD: Neuropsychological tests were administered to 42 patients with schizophrenia or other psychosis to assess cognitive functioning, and the experience sampling method (a structured diary technique assessing current context and mood in daily life) was used to assess 1) appraised subjective stress related to daily events and activities and 2) emotional reaction to these daily life stressors. RESULTS: Multilevel random regression analyses showed that in some instances, cognitive functioning did not alter emotional reaction to stress. In other instances, an inverse relationship was found, indicating that a better performance on neuropsychological tests was related to greater emotional reaction to stress. CONCLUSIONS: The results indicate that emotional reaction to stress in the daily lives of patients with schizophrenia may not be a consequence of cognitive impairments and that the two mechanisms may act through different pathways. Such pathways may be related to the extremes of clinical outcome that have been observed in schizophrenia: an episodic, reactive, good outcome and a more chronic form characterized by high levels of negative symptoms and cognitive impairments.

Adult↗
PubMedDate not supplied

Does urbanicity shift the population expression of psychosis?

Growing up in an urban area has been shown to be associated with an increased risk of psychotic disorder in later life. While it is commonly held that a only a tiny fraction of exposed individuals will develop schizophrenia, recent evidence suggests that expression of psychosis in exposed individuals may be much more common, albeit at attenuated levels. Findings are based on a population sample of 2548 adolescents and young adults aged originally 14-24 years, and followed up over almost 5 years up to ages 17-28 years. Trained psychologists assessed all these subjects with the core psychosis sections on delusions and hallucinations of the Munich-Composite International Diagnostic Interview. Growing up in an urban area was associated with an increased risk of expression of psychosis in the adolescents and young adults (adjusted OR 1.31, 95% CI 1.03-1.66). The proxy environmental risk factor that urbanicity represents may shift a relatively large section of the adolescent population along a continuum of expression of psychosis. Other causal influences may be required to make the transition to schizophrenia in adult life.

Adolescent↗