Cognition as predictor of current and follow-up depressive symptoms in the general population

OBJECTIVE

Previous studies have reported an association between depression and poor cognitive functioning. Unknown is to what degree such associations are merely state-related or reflect an enduring depression vulnerability. This study examined whether cognitive deficits predict current and/or follow-up (sub)clinical depressive symptoms in the general population.

METHOD

A population-based sample of 569 female twins and 43 of their sisters completed a neuropsychological battery. Cross-sectional and prospective associations between depressive symptoms measured at the subclinical [Symptom Checklist-90 (SCL-90)] and clinical level (Structured Clinical Interview for DSM-IV disorders) and neuropsychological factors (episodic memory and information processing speed) were examined.

RESULTS

Structured Clinical Interview for DSM-IV disorders baseline depressive symptoms were significantly associated with information processing speed but not with episodic memory. Episodic memory was significantly associated with follow-up SCL-90 depressive symptoms.

CONCLUSION

Being depressed is accompanied by slower information processing. Poor memory functioning may be a predictor for the onset of subclinical depressive symptoms.

Cognitive performance and grey matter density in psychosis: functional relevance of a structural endophenotype

BACKGROUND

Structural brain changes and cognitive impairments have been identified as indicators of genetic risk for schizophrenia. However, the pattern of associations between such structural and functional liability markers has been less well investigated.

METHODS

Magnetic resonance imaging data and cognitive assessments were acquired in 31 patients with psychosis, 32 non-psychotic first-degree relatives and 28 controls. The relationship between cerebral grey matter density and cognitive performance was examined using computational morphometry.

RESULTS

Two out of 6 cognitive tests revealed significant associations with grey matter density in regions of the frontal lobe, basal ganglia, thalamus and cerebellum in patients and relatives. In patients, poorer executive functioning was associated with cerebellar grey matter density deficits. In relatives, poorer executive functioning was associated with increased grey matter density in the cerebellum and frontal lobe. In both patients and relatives, strategic retrieval from semantic memory was positively associated with grey matter density in basal ganglia structures. Some additional negative associations in the patients differentiated this group from relatives.

CONCLUSIONS

The overlap in structure-function relationships in individuals with schizophrenia and those with liability for the disorder may suggest that regional grey matter density alterations functionally alter particular neurocircuits, which could lead to cognitive deficits. The non-overlapping structure-function correlations may reflect disease-related or compensatory mechanisms.

A systematic review and meta-analysis of the psychosis continuum: evidence for a psychosis proneness-persistence-impairment model of psychotic disorder

A systematic review of all reported incidence and prevalence studies of population rates of subclinical psychotic experiences reveals a median prevalence rate of around 5% and a median incidence rate of around 3%. A meta-analysis of risk factors reveals associations with developmental stage, child and adult social adversity, psychoactive drug use, and also male sex and migrant status. The small difference between prevalence and incidence rates, together with data from follow-up studies, indicates that approximately 75-90% of developmental psychotic experiences are transitory and disappear over time. There is evidence, however, that transitory developmental expression of psychosis (psychosis proneness) may become abnormally persistent (persistence) and subsequently clinically relevant (impairment), depending on the degree of environmental risk the person is additionally exposed to. The psychosis proneness-persistence-impairment model considers genetic background factors impacting on a broadly distributed and transitory population expression of psychosis during development, poor prognosis of which, in terms of persistence and clinical need, is predicted by environmental exposure interacting with genetic risk.

Subtle gene-environment interactions driving paranoia in daily life

It has been suggested that genes impact on the degree to which minor daily stressors cause variation in the intensity of subtle paranoid experiences. The objective of the present study was to test the hypothesis that catechol-O-methyltransferase (COMT) Val(158)Met and brain-derived neurotrophic factor (BDNF) Val(66)Met in part mediate genetic effects on paranoid reactivity to minor stressors. In a general population sample of 579 young adult female twins, on the one hand, appraisals of (1) event-related stress and (2) social stress and, on the other hand, feelings of paranoia in the flow of daily life were assessed using momentary assessment technology for five consecutive days. Multilevel regression analyses were used to examine moderation of daily life stress-induced paranoia by COMT Val(158)Met and BDNF Val(66)Met genotypes. Catechol-O-methyltransferase Val carriers displayed more feelings of paranoia in response to event stress compared with Met carriers. Brain-derived neurotrophic factor Met carriers showed more social-stress-induced paranoia than individuals with the Val/Val genotype. Thus, paranoia in the flow of daily life may be the result of gene-environment interactions that can be traced to different types of stress being moderated by different types of genetic variation.

Meta-analyses of cognitive functioning in euthymic bipolar patients and their first-degree relatives

BACKGROUND

Previous work suggests that impairments in executive function and verbal memory in particular may persist in euthymic bipolar patients and serve as an indicator of genetic risk (endophenotype).

METHOD

A systematic review of the literature was undertaken. Effects sizes were extracted from selected papers and pooled using meta-analytical techniques.

RESULTS

In bipolar patients, large effect sizes (d>0.8) were noted for executive functions (working memory, executive control, fluency) and verbal memory. Medium effect sizes (0.5<d<0.8) were reported for aspects of executive function (concept shifting, executive control), mental speed, visual memory, and sustained attention. Small effect sizes (d<0.5) were found for visuoperception. In first-degree relatives, effect sizes were small (d<0.5), but significantly different from healthy controls for executive function and verbal memory in particular.

CONCLUSIONS

Executive function and verbal memory are candidate bipolar endophenotypes given large deficits in these domains in bipolar patients and small, but intermediate, cognitive impairments in first-degree relatives.

[A psychosis proneness-persistence-impairment model of psychotic disorders]

There is evidence that the normally transitory developmental expression of psychosis (psychosisproneness) may first of all become abnormally persistent (persistence) and later on become clinically relevant (impairment), depending on the amount of environmental risk to which the person is exposed. According to the psychosis-proneness-persistence impairment model, genetic background factors can impact on a transitory expression of psychosis. Whether or not this will lead to a poor prognosis in terms of persistence and clinical need will depend on the interaction between environmental exposure and genetic risk.

Cognitive alterations in groups at risk for psychosis: neutral markers of genetic risk or indicators of social disability?

OBJECTIVE

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.

METHOD

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.

RESULTS

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.

CONCLUSION

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.

Subclinical psychotic experiences and cognitive functioning as a bivariate phenotype for genetic studies in the general population

OBJECTIVE

Cognitive deficits may be vulnerability markers for the development of schizophrenia. This study examined whether cognitive deficits are related to specific dimensions of subclinical psychotic experiences and whether associations between these variables are caused by additive genetic, common environmental and/or individual-specific environmental factors.

METHOD

A general population sample of 298 female twin pairs completed the Community Assessment of Psychic Experiences and a neuropsychological test battery. Associations between subclinical positive and negative psychotic dimensions and neuropsychological factors (episodic memory and information processing speed) were examined. Univariate correlation and structural equation analyses were performed to explore the role of genetic and environmental factors in the phenotypes separately. Bivariate correlation and structural equation analyses were applied to examine the causes of association.

RESULTS

There were significant correlations between information processing speed and both the positive (r=.11; p<.05) and the negative dimension (r=.10; p<.05). For the negative dimension and for speed of processing, the data suggested a model that included genetic factors. The observed phenotypic correlation between the negative dimension and information processing speed could be solely explained in terms of additive genetic factors. Although the comparison of the correlations for MZ and DZ pairs did not give a clear indication as to the underlying causes of the association, structural equation modelling suggested that the observed phenotypic correlation between the negative dimension and information processing speed could be solely explained in terms of additive genetic factors.

CONCLUSION

Negative symptoms and information processing speed are associated at the subclinical level and this association appears to be influenced by genetic factors exclusively. Bivariate psychosis phenotypes may represent suitable candidates for molecular genetic studies in the general population.

Relationship between DHA status at birth and child problem behaviour at 7 years of age

Animal studies have demonstrated behavioural effects of long-chain polyunsaturated fatty acid (LC-PUFA) deficiencies and in humans, several psychiatric disorders have been linked to abnormal essential fatty acid metabolism. The aim of this study was to examine the relationship between LC-PUFA status at birth and the later development of problem behaviour. In a sample of 393 children, higher levels of docosahexaenoic acid (DHA) at birth were associated with lower levels of internalising problem behaviour at age 7 years. The association was markedly present in the infants fed with artificial formula (n=215, Beta=-0.32, P=0.000), but absent in the infants fed with human milk (n=170, Beta=0.11, P=0.325). The associations between arachidonic acid and internalising or externalising behaviour were neither large nor significant. The results suggest that perinatal DHA status may have long-term behavioural consequences. Therefore, we suggest to include measures of problem behaviour in future trials of LC-PUFA supplementation of mothers and/or infants.

Validity and reliability of the CAPE: a self-report instrument for the measurement of psychotic experiences in the general population

OBJECTIVE

General population longitudinal cohort studies have demonstrated the prognostic validity of self-reported psychotic experiences, but data on reliability and cross-validation with interview-based measures of these experiences are sparse. This study tested the reliability and validity of the Community Assessment of Psychic Experiences (CAPE42).

METHOD

At baseline, the CAPE42 was used to measure the subclinical psychosis phenotype in a general population sample (n = 765). At follow-up (mean interval: 7.7 months), the Structured Interview for Schizotypy, Revised (SIS-R), the Brief Psychiatric Rating Scale (BPRS), and the CAPE42 were administered (n = 510).

RESULTS

Baseline self-reported dimensions of psychosis were specifically and independently associated with their equivalent interview-based dimension at follow-up (standardized effect sizes of 0.4-0.5) and with their equivalent self-reported measure (standardized effect sizes of 0.6-0.8).

CONCLUSION

The results indicate that self-reported dimensions of psychotic experiences in general population samples appear to be stable, reliable and valid.

Attribution style and psychosis: evidence for an externalizing bias in patients but not in individuals at high risk

BACKGROUND

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.

METHOD

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).

RESULTS

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.

CONCLUSIONS

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.

A prospective study of the transition rates of subthreshold (hypo)mania and depression in the general population

BACKGROUND

Previous work suggests that subthreshold depression and subthreshold (hypo)mania are common, although little is known about the prognosis in terms of transition to clinical disorder. This paper presents data on the temporal relationship between subthreshold and clinical expression of mood phenotypes.

METHOD

In a random general population sample of 7076 individuals, symptoms of depression and (hypo)mania were measured with the Composite International Diagnostic Interview (CIDI) at baseline, after 1 year, and 2 years later.

RESULTS

At baseline, the lifetime prevalences of depressive and (hypo)manic symptoms were 17.2% and 1.2% respectively. Predictive values of mood symptoms for a DSM-III-R mood disorder ranged from 14.3% to 50%. (Hypo)manic mood symptoms had much higher predictive values than unipolar manifestations, not only for bipolar disorder but also for major depression.

CONCLUSIONS

The subthreshold expressions of depression and (hypo)mania are prevalent and continuous with more severe clinical states. The cross-prediction of mood symptoms may support a continuum from depressive to (hypo)manic symptoms. The high predictive value of (hypo)manic symptoms for mood disorders suggests that the experience of (hypo)manic symptoms is a stronger indicator of vulnerability for mood dysregulation than the experience of depressive symptoms.

Evidence for instrument and family-specific variation of subclinical psychosis dimensions in the general population

It is unknown to what degree dimensions of schizotypy (subclinical psychosis) show independent, family-specific variation in the general population. Psychologists administered the Community Assessment of Psychic Experiences, the Structured Interview for Schizotypy-Revised (SIS-R), and the Brief Psychiatric Rating Scale to 257 subjects pertaining to 82 general population families. All 3 instruments showed family-specific variation for positive and negative subclinical psychosis dimensions with between-families proportions of total variance between 10% and 40%. However, only the SIS-R showed family-specific variation of the negative dimension independent of its correlation with the positive dimension. The positive dimension of subclinical psychosis shows familial-specific variation in samples unselected for psychiatric disorder, suggesting dimensional liability in the population. The SIS-R additionally captures family-specific variation in the negative domain.

Are apparent associations between parental representations and psychosis risk mediated by early trauma?

OBJECTIVE

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.

METHOD

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).

RESULTS

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.

CONCLUSION

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.

Early trauma may increase the risk for psychotic experiences by impacting on emotional response and perception of control

OBJECTIVE

Exposure to early trauma may increase the risk of dysfunctional responses to anomalous psychotic experiences resulting in psychotic symptom formation.

METHOD

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.

RESULTS

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).

CONCLUSION

Early experience of trauma may create lasting cognitive and affective vulnerabilities to develop clinical symptoms arising out of early, non-clinical psychotic experiences.

Early maternal stress and health behaviours and offspring expression of psychosis in adolescence

OBJECTIVE

It has been suggested that influences operating early in life may affect the risk of postpubertal psychosis outcomes. This hypothesis was tested using a broad outcome of psychotic symptoms expressed in adolescence (prevalence: 15.6%).

METHOD

Findings are based on a longitudinal, population-based cohort study of 963 adolescents aged 15-20 years and their parents in the area of Munich, Germany. Trained psychologists assessed adolescents with the Munich-Composite International Diagnostic Interview. Independently, direct diagnostic interviews were conducted with the parents.

RESULTS

A range of medical complications of pregnancy and delivery, including lower birth weight, were not associated with the psychosis outcome. However, a number of maternal health behaviours and experiences did show associations, independent of confounders.

CONCLUSION

Not maternally reported medical complications of pregnancy and delivery, but maternal prenatal health behaviours predicted expression of psychosis along a continuum in adolescence. This effect may either be direct or constitute a proxy for later postnatal maternal behaviours associated with psychosis risk in the offspring.

Hallucinatory experiences and onset of psychotic disorder: evidence that the risk is mediated by delusion formation

OBJECTIVE

To examine the hypothesis that the risk for onset of psychotic disorder in individuals with self-reported hallucinatory experiences (HE) would be higher in those who developed delusional ideation (DE) than in those who did not.

METHOD

A population sample of 4673 individuals were interviewed with the Composite International Diagnostic Interview at baseline and 1 and 3 years later. At year 3, clinical re-interview took place to identify onset of psychotic disorder.

RESULTS

Given the presence of HEs at baseline, the increase in risk of having the psychosis outcome at year 3 was much higher in those with DE at year 1 than in those without DE (risk difference between individuals with and without DE: 18.72%, 95% CI: 2.22-35.23, chi(2) = 4.94, df = 1, P = 0.026).

CONCLUSION

The results are in line with current psychological theories stating that clinical outcome of psychosis-like experiences is related to the development of secondary beliefs and appraisals.

Dimensions of depression, mania and psychosis in the general population

BACKGROUND

In order to investigate whether correlated but separable symptom dimensions that have been identified in clinical samples also have a distribution in the general population, the underlying structure of symptoms of depression, mania and psychosis was studied in a general population sample of 7072 individuals.

METHOD

Data were obtained from the three measurements of the Netherlands Mental Health Survey and Incidence Study (NEMESIS). Symptoms of depression, mania and the positive symptoms of psychosis were assessed using the Composite International Diagnostic Interview. Confirmatory factor-analysis was used to test statistically the fit of hypothesized models of one, two, three or seven dimensions.

RESULTS

The seven-dimensional model comprising core depression, sleep problems, suicidal thoughts, mania, paranoid delusions, first-rank delusions and hallucinations fitted the data best, whereas the unidimensional model obtained the poorest fit. This pattern of results could be replicated at both follow-up measurements. The results were similar for the subsamples with and without a lifetime DSM-III-R diagnosis. The seven dimensions were moderately to strongly correlated, with correlations ranging from 0.18 to 0.73 (mean 0.45).

CONCLUSIONS

In the general population, seven correlated but separable dimensions of experiences exist that resemble dimensions of psychopathology seen in clinical samples with severe mental illness. The substantial correlations between these dimensions in clinical and non-clinical samples may suggest that there is aetiological overlap between the different dimensions regardless of level of severity and diagnosable disorder.

The wider social environment and mental health service use

OBJECTIVE

Previous studies associating neighbourhood context with mental health service use typically included limited sets of confounders.

METHOD

A data set including patients registered in a Case Register and population controls was subjected to multilevel analyses, including neighbourhood exposures and individual level confounders. In addition, days of care consumption of patients was addressed.

RESULTS

The association between socioeconomic deprivation and social capital on the one hand and mental health service use rates on the other could be attributed to individual level differences. However, number of days of service consumption was higher in neighbourhoods with more informal social control. In residentially stable neighbourhoods only, socioeconomic deprivation was associated with lower levels of service consumption.

CONCLUSION

Higher levels of social control may induce patients to remain in contact with mental health services. Furthermore, higher levels of deprivation in neighbourhoods with little population mobility may result in reduced expectations of recovery and/or increased tolerance.

Sex differences in emotional reactivity to daily life stress in psychosis

BACKGROUND

The expression of schizophrenia has been reported to differ between the sexes. The current study investigates whether these sex differences in clinical expression are reflected in one underlying mechanism that may be causally related to psychosis, namely increases in stress sensitivity in daily life.

METHOD

Forty-two participants (22 men, 20 women) with Research Diagnostic Criteria-defined psychotic disorder in a state of clinical remission were studied with the Experience Sampling Method (a structured diary technique assessing current context and mood in daily life) to assess (1) appraised subjective stress related to daily events and activities and (2) emotional reactivity conceptualized as changes in both negative affect and positive affect in relation to the subjective stress. Data were collected from January 1997 to May 1999.

RESULTS

Multilevel regression analyses revealed that women reported a significantly (p < .05) increased emotional reactivity to daily life stress compared with men, reflected in both an increase in negative affect and a decrease in positive affect.

CONCLUSION

These results suggest that gender differences may not be limited to the characteristics of psychosis but may also be reflected in underlying etiologic mechanisms. Furthermore, these results might strengthen the hypothesis that women are more susceptible than men to a schizoaffective expression of schizophrenia.

Childhood abuse as a risk factor for psychotic experiences

OBJECTIVE

To examine the hypothesis that individuals from the general population who report childhood abuse are at increased risk of developing positive psychotic symptoms.

METHOD

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.

RESULTS

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).

CONCLUSION

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.

Alterations in theory of mind in patients with schizophrenia and non-psychotic relatives

OBJECTIVE

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.

METHOD

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.

RESULTS

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.

CONCLUSION

Changes in theory of mind are associated with schizophrenia liability. General cognitive ability and neuropsychological measures seem to mediate only part of this association.

Can cognitive deficits explain differential sensitivity to life events in psychosis?

BACKGROUND

Life events (LE) have been found to influence the onset and course of psychotic disorders. It has been suggested that LE have their effect by increasing underlying sensitivity to daily life stress, a reported vulnerability marker for psychosis. As increased stress-sensitivity and cognitive impairments have been shown to be negatively associated with each other in patient populations, it is attractive to hypothesise that the impact of LE on sensitivity to daily stress is modified by the degree of cognitive impairment, higher levels of cognitive impairment giving rise to reduced impact of LE on daily life stress-sensitivity.

METHODS

Patients with psychotic illness (n = 42) were studied with a) a standard battery of neuropsychological tests to assess cognitive functioning, b) the Experience Sampling Method (a structured diary technique assessing current context and mood in daily life) to assess (i) appraised subjective stress related to daily events and activities, and (ii) emotional reactivity conceptualised as changes in both negative affect (NA) and positive affect (PA), and c) the Brown and Harris Life Event and Difficulties Schedule to assess LE over the last year.

RESULTS

Multilevel regression analyses showed that a prior history of LE increased the sensitivity for daily life stress in subjects with the best performance on the cognitive tests.

CONCLUSIONS

Subjects with cognitive impairments, who already were shown to have lower levels of sensitivity to daily life stress (Myin Germeys et al. 2002), may additionally be less reactive to prior exposure to LE. This result fits with the notion of separate affective and cognitive pathways of symptom formation in psychosis, the cognitive pathway being characterised by severe cognitive deficits and the affective pathway by increased levels of stress-sensitivity associated with prior exposure to LE.