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.

Functional disability and depression in the general population. Results from the Netherlands Mental Health Survey and Incidence Study (NEMESIS).

OBJECTIVE: Data on the temporal relationships between duration of depression and recovery and functional disability are sparse. These relationships were examined in subjects from the general population (n = 250) with newly originated episodes of DSM-III-R major depression. METHOD: The Netherlands Mental Health Survey and Incidence Study is a prospective epidemiological survey in the adult population (n = 7076), using the Composite International Diagnostic Interview (CIDI). Duration of depression and duration of recovery over 2 years were assessed with a life chart interview. Functional disabilities were assessed with the MOS-SF-36 and with absence days from work. RESULTS: Functional disabilities and absence days in depressed individuals were not found to be associated with duration of depression. Functioning in daily activities improved with longer duration of recovery but social functioning not. CONCLUSION: Functioning deteriorates by actual depressive symptomatology and comorbid anxiety but not by longer duration of depression. After symptomatic recovery, functioning improves to premorbid level, irrespective of the length of the depression. Improvements in daily activities and work can be expected with longer duration of recovery.

Rapid onset of comorbidity of common mental disorders: findings from the Netherlands Mental Health Survey and Incidence Study (NEMESIS).

OBJECTIVE: In a cohort of subjects with no history of psychopathology, we determined a 3-year incidence and the risk factors of comorbid and pure mood, anxiety and substance use disorders. METHOD: Data were obtained from the Netherlands Mental Health Survey and Incidence Study (NEMESIS), a longitudinal community study in which 4796 adults were interviewed in 1996, 1997 and 1999 with the Composite International Diagnostic Interview. RESULTS: Of 2869 cases at risk, 10.8% developed an incident disorder within 3 years, of which 16.1% was comorbid. Neuroticism, childhood trauma and parental psychiatric history were more strongly associated with comorbid than with pure disorders. No differences emerged in events occurring in the first year after baseline, but events in the period thereafter showed markedly stronger associations with comorbidity and pure mood disorder than with pure anxiety and substance use disorder. Functional disability was also linked more strongly to comorbidity and pure mood disorder. CONCLUSION: Clear risk factors exist for the rapid onset of comorbidity. Interventions are needed to prevent rapid comorbidity in subjects who recently developed a primary disorder.

Levels of disability in major depression: findings from the Netherlands Mental Health Survey and Incidence Study (NEMESIS).

BACKGROUND: Information on the distribution of disability associated with major depression (MD) across different groups of patients is of interest to health policy and planning. We examined the associations of severity and type (a single or recurrent episode) of MD with disability in a Dutch general population sample. METHODS: We used data from the first wave (1996) of the Netherlands Mental Health Survey and Incidence Study (NEMESIS). MD 'severity' and 'type' were diagnosed with the help of the Composite International Diagnostic Interview according to DSM-III-R criteria. SF-36 scores, days ill in bed and days absent from work were taken as indicators of disability. The differences in these variables were studied by means of variance and regression analysis. RESULTS: Recurrent MD was found not to be associated with more disability than single episode MD. Higher 'severity' classes were associated with more disability. However, the degree of disability between 'moderate' and 'severe' MD differed only very slightly. The difference in disability between non-depressed and mildly depressed individuals had a larger effect than between each successive pair of 'severity' classes. CONCLUSIONS: Three groups of MD can be distinguished based on the associated degree of disability: 'mild', 'moderate to severe' and 'severe with psychotic features'. In the future, these groups can be used to describe the distribution of disability in the depressed population. The marked difference between 'mild' MD and no MD suggests that 'mild' cases should be considered relevant.

Self-reported psychotic experiences in the general population: a valid screening tool for DSM-III-R psychotic disorders?

OBJECTIVE: To examine the diagnostic value of self-reported psychotic-like experiences for DSM-III-R psychotic disorders. METHOD: A general population sample of 7076 subjects aged 18-64 years was interviewed with the Composite International Diagnostic Interview (CIDI) and, if there was evidence of psychotic experiences, the Structured Clinical Interview for DSM-III-R. RESULTS: The probability of having a psychotic disorder increased in a dose-response fashion with the level of self-reported psychotic experiences, but individual CIDI psychotic experience ratings had relatively low post-test probabilities (PPs) (range: 5.1-26.5%). However, limiting the sample to individuals who had been in contact with mental health services substantially improved PPs (range: 13.3-43.1%). CONCLUSION: Screening for psychosis in the population carries a high risk of stigmatization in false-positive cases and violation of the right 'not to know' in true-positive cases. However, in mental health care users, self-reported psychotic experiences may be a useful screening tool in individuals who have already developed help-seeking.

Temporal sequencing of lifetime mood disorders in relation to comorbid anxiety and substance use disorders--findings from the Netherlands Mental Health Survey and Incidence Study.

BACKGROUND: Little is known about the temporal sequencing of psychiatric disorders. The aim of this study was to obtain insight into patterns of co-occurrence of DSM-III-R mood disorders in relation to anxiety and substance use disorders, their temporal sequencing and the sociodemographic and long-term vulnerability predictors of this temporal sequencing. METHODS: Data are from the Netherlands Mental Health Survey and Incidence Study (NEMESIS), a psychiatric epidemiological study in a representative sample of 7,076 adults aged 18-64. RESULTS: Of those who had ever experienced a mood disorder, 46 % of males and 57 % of females had a history of anxiety disorders, and 43 % and 15 % of substance use disorders. Mood disorders were associated with all anxiety and substance use disorders, except with alcohol abuse among males. In the majority of anxiety-comorbid cases, the mood disorder arose after the anxiety disorder; the pattern for substance use-comorbid disorders was more variable. Deviation from the usual sequence of major depression and anxiety disorders was more often seen among females, subjects with a higher educational level, subjects who experienced childhood parental divorce, and subjects who experienced childhood emotional neglect. CONCLUSIONS: When comorbid with anxiety disorders, mood disorders clearly tend to be secondary. Few of the studied demographic factors, familial vulnerability factors and childhood life events predict the sequencing of mood disorders in relation to other disorders.

Discrimination and delusional ideation.

BACKGROUND: In the UK and The Netherlands, people with high rates of psychosis are chronically exposed to discrimination. AIMS: To test whether perceived discrimination is associated longitudinally with onset of psychosis. METHOD: 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). RESULTS: 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. CONCLUSIONS: Perceived discrimination may induce delusional ideation and thus contribute to the high observed rates of psychotic disorder in exposed minority populations.

The effects of co-morbidity on the onset and persistence of generalized anxiety disorder in the ICPE surveys. International Consortium in Psychiatric Epidemiology.

BACKGROUND: Although it is well known that generalized anxiety disorder (GAD) is highly co-morbid with other mental disorders, little is known about the extent to which earlier disorders predict the subsequent first onset and persistence of GAD. These associations are examined in the current report using data from four community surveys in the World Health Organization (WHO) International Consortium in Psychiatric Epidemiology (ICPE). METHOD: The surveys come from Brazil, Canada, the Netherlands and the United States. The Composite International Diagnostic Interview (CIDI) was used to assess DSM-III-R anxiety, mood and substance use disorders in these surveys. Discrete-time survival analysis was used to examine the associations of retrospectively reported earlier disorders with first onset of GAD. Logistic regression analysis was used to examine the associations of the disorders with persistence of GAD. RESULTS: Six disorders predict first onset of GAD in all four surveys: agoraphobia, panic disorder, simple phobia, dysthymia, major depression and mania. With the exception of simple phobia, only respondents with active disorders have elevated risk of GAD. In the case of simple phobia, in comparison, respondents with a history of remitted disorder also have consistently elevated risk of GAD. Simple phobia is also the only disorder that predicts the persistence of GAD. CONCLUSIONS: The causal processes linking temporally primary disorders to onset of GAD are likely to be state-dependent. History of simple phobia might be a GAD risk marker. Further research is needed to explore the mechanisms involved in the relationship between simple phobia and subsequent GAD.

Predictors of first incidence of DSM-III-R psychiatric disorders in the general population: findings from the Netherlands Mental Health Survey and Incidence Study.

OBJECTIVE: To investigate determinants of 12-month first incidence of DSM-III-R mood disorder (MD), anxiety disorder (AD) and substance use disorder (SUD) in the general population. METHOD: Data are from the Netherlands Mental Health Survey and Incidence Study (NEMESIS), a prospective epidemiologic study in which a representative sample of 7076 adults aged 18-64 years were interviewed with the Composite International Diagnostic Interview. New cases diagnosed 12 months after baseline were compared with never diagnosed controls on sociodemographic and psychosocial variables. RESULTS: Multivariate, the only demographic variable associated with incidence of MD was female gender. The strongest predictors were negative life events and ongoing difficulties. High level of neuroticism was also associated. Incidence of AD was likewise predicted by female gender. Negative life events and ongoing difficulties were also significant predictors, though weaker than for MD. Incidence of SUD was more common among males, young adults, people not living with a partner and those experiencing positive life events. CONCLUSION: Incident MD and AD were predicted more strongly by life events, and SUD more strongly by demographic factors.

Cannabis use and psychosis: a longitudinal population-based study.

Cannabis use may increase the risk of psychotic disorders and result in a poor prognosis for those with an established vulnerability to psychosis. A 3-year follow-up (1997-1999) is reported of a general population of 4,045 psychosis-free persons and of 59 subjects in the Netherlands with a baseline diagnosis of psychotic disorder. Substance use was assessed at baseline, 1-year follow-up, and 3-year follow-up. Baseline cannabis use predicted the presence at follow-up of any level of psychotic symptoms (adjusted odds ratio (OR) = 2.76, 95% confidence interval (CI): 1.18, 6.47), as well as a severe level of psychotic symptoms (OR = 24.17, 95% CI: 5.44, 107.46), and clinician assessment of the need for care for psychotic symptoms (OR = 12.01, 95% CI: 2.24, 64.34). The effect of baseline cannabis use was stronger than the effect at 1-year and 3-year follow-up, and more than 50% of the psychosis diagnoses could be attributed to cannabis use. On the additive scale, the effect of cannabis use was much stronger in those with a baseline diagnosis of psychotic disorder (risk difference, 54.7%) than in those without (risk difference, 2.2%; p for interaction = 0.001). Results confirm previous suggestions that cannabis use increases the risk of both the incidence of psychosis in psychosis-free persons and a poor prognosis for those with an established vulnerability to psychotic disorder.

Prevalence of psychotic disorder and community level of psychotic symptoms: an urban-rural comparison.

BACKGROUND: Urban and rural populations have different rates of psychotic illness. If psychosis exists as a continuous phenotype in nature, urban-rural population differences in the rate of psychotic disorder should be accompanied by similar differences in the rate of abnormal mental states characterized by psychotic or psychosislike symptoms. METHODS: A random sample of 7076 individuals aged 18 to 64 years were interviewed by trained lay interviewers with the Composite International Diagnostic Interview. Approximately half of those with evidence of psychosis according to the Composite International Diagnostic Interview were additionally interviewed by clinicians. We investigated associations between a 5-level urbanicity rating and (1) any DSM-III-R diagnosis of psychotic disorder (sample prevalence, 1.5%), (2) any rating of hallucinations and/or delusions (sample prevalence, 4.2%), and (3) any rating of psychotic or psychosislike symptoms (sample prevalence, 17.5%). RESULTS: Level of urbanicity was associated not only with DSM-III-R psychotic disorder (adjusted odds ratio [OR] over 5 levels, 1.47; 95% confidence interval [CI], 1.25-1.72), but also, independently, with any rating of delusion and/or hallucination (adjusted OR, 1.28; 95% CI, 1.17-1.40; clinician-assessed psychotic symptoms only: OR, 1.30; 95% CI, 1.03-1.64) and any rating of psychosislike symptom (adjusted OR, 1.18; 95% CI, 1.13-1.24). Psychotic symptoms were strongly and independently associated with psychotic disorder, regardless of the level of urbanization. CONCLUSIONS: Community level of psychotic and psychosislike symptoms may be inextricably linked to the prevalence of psychotic disorder. The prevalence of abnormal mental states that facilitate development to overt psychotic illness increases progressively with level of urbanization.

Care utilization and outcome of DSM-III-R major depression in the general population. Results from the Netherlands Mental Health Survey and Incidence Study (NEMESIS).

OBJECTIVE: To assess care utilization, individual characteristics and clinical and functional outcomes for various modalities of professional care in people with DSM-III-R major depression. METHOD: Psychiatric diagnoses were determined at baseline and 12-month follow-up in a representative sample (N = 7076) of the Dutch population, using the Composite International Diagnostic Interview (CIDI). RESULTS: A total of 45.3% of the 223 individuals with major depression received professional care in the 12 months between baseline and follow-up, and 42.6% of these were treated with antidepressant medication. Higher level of care was associated with clinical factors and functional limitations. Clinical outcomes were poorly correlated with functional outcomes. Mild to moderate effects in functional outcome were found for all care modalities. CONCLUSION: Outcome of antidepressant treatment can be improved and such treatment should focus on the more severe forms of depression. Functional outcome assessment is recommended in addition to clinical assessment.

Predictors of incident care service utilisation for mental health problems in the Dutch general population.

BACKGROUND: The determinants of first-time ('incident') use of primary care and mental health care services for mental health problems have not been previously investigated. Such information is needed to identify new client groups and to gain a better understanding of causal factors. METHOD: Data were derived from the Netherlands Mental Health Survey and Incidence Study, NEMESIS, a prospective general population study of adults. Potential predictors of care use (psychiatric disorders, burden of illness, sociodemographic characteristics) were recorded in the first wave of the study, and the utilisation of care services in the second wave. Psychiatric diagnoses were based on the Composite International Diagnostic Interview (CIDI) 1.1. RESULTS: Six of the ten indicators linked to the frequent utilisation of care were found not to be associated with incident use: higher age, lower income, living alone, paid employment, mood disorders and anxiety disorders. Four other indicators showed associations with both frequent and incident use: female gender, higher numbers of restricted activity days, poorer social functioning and unmet care needs. Two predictors of incident use only were lower educational attainment and being in treatment for a somatic disorder. CONCLUSION: New clients who come to primary health care or mental health care services with mental health problems are found in all age groups. They are more likely to be women, to have less education, to be in treatment for a somatic disorder and to have functional problems related to their mental health problems.

The structure and stability of common mental disorders: the NEMESIS study.

BACKGROUND: We analyzed the underlying latent structure of 12-month DSM-III-R diagnoses of 9 common disorders for the general population in the Netherlands. In addition, we sought to establish (1) the stability of the latent structure underlying mental disorders across a 1-year period (structural stability) and (2) the stability of individual differences in mental disorders at the level of the latent dimensions (differential stability). METHODS: Data were obtained from the first and second measurement of the Netherlands Mental Health Survey and Incidence Study (NEMESIS) (response rate at baseline: 69.7%, n = 7076; 1 year later, 79.4%, n = 5618). Nine common DSM-III-R diagnoses were assessed twice with the Composite International Diagnostic Interview with a time lapse of 1 year. Using structural equation modeling, the number of latent dimensions underlying these diagnoses was determined, and the structural and differential stability were assessed. RESULTS: A 3-dimensional model was established as having the best fit: a first dimension underlying substance use disorders (alcohol dependence, drug dependence); a second dimension for mood disorders (major depression, dysthymia), including generalized anxiety disorder; and a third dimension underlying anxiety disorders (simple phobia, social phobia, agoraphobia, and panic disorder). The structural stability of this model during a 1-year period was substantial, and the differential stability of the 3 latent dimensions was considerable. CONCLUSIONS: Our results confirm the 3-dimensional model for 12-month prevalence of mental disorders. Results underline the argument for focusing on core psychopathological processes rather than on their manifestation as distinguished disorders in future population studies on common mental disorders.

The distribution of psychiatric and somatic III health: associations with personality and socioeconomic status.

OBJECTIVE: Psychiatric and somatic disorders frequently co-occur in the same individuals. We examined whether this happens because these types of morbidity share risk factors or because they are risk factors for each other. METHODS: Negative binomial regression was used to examine, in a random sample of Dutch adults (N = 7076), cross-sectional associations of sociodemographic and personality variables like income and neuroticism with the presence, over 1 year, of 30 somatic and 13 psychiatric disorders, with the latter diagnosed by structured interview. We examined to what extent the links of these variables with these two morbidity types were independent of each other. RESULTS: This population experienced 5050 somatic and 2438 psychiatric disorders during the preceding year. Subjects reporting more somatic disorders had more psychiatric disorders. Neuroticism, followed closely by low educational attainment, was the strongest correlate of both morbidity types. After adjustment for all other covariates including somatic morbidity, the number of psychiatric diagnoses rose 1.84-fold (95% confidence interval = 1.74-1.94) per standard deviation increase in neuroticism. Likewise, adjusted for all other covariates including psychiatric diagnoses, 1.42 (95% confidence interval = 1.35-1.50) times more somatic disorders were reported per standard deviation increase in neuroticism. CONCLUSIONS: Personal features like neuroticism and low educational attainment are linked with psychiatric and with somatic morbidity. These links are largely independent. Although this study was cross-sectional, the results suggest that these different types of morbidity may have overlapping etiologies. Key words: Comorbidity, multimorbidity coefficient, negative binomial regression, epidemiology, neuroticism, social class.

Determinants of poor 1-year outcome of DSM-III-R major depression in the general population: results of the Netherlands Mental Health Survey and Incidence Study (NEMESIS).

OBJECTIVE: To investigate risk factors of poor 1-year outcome of major depression in the general population and to compare the results with data from clinical populations. METHOD: Psychiatric diagnoses were determined in a representative sample (N = 7,076) of the Dutch general population, using the Composite International Diagnostic Interview (CIDI) at baseline and 12 months later. A broad range of potential risk factors were evaluated. RESULTS: Of the depressed people at baseline, 28.3% were depressed 12 months later. Younger age, severity of depression, longer duration of previous episodes, the presence of anhedonia and early awakening, external locus of control and multiple negative life events appear to be risk factors. CONCLUSION: Poor outcome of major depression is frequent in the general population. Largely the same risk factors are involved as in clinical populations.

Same-sex sexual behavior and psychiatric disorders: findings from the Netherlands Mental Health Survey and Incidence Study (NEMESIS).

BACKGROUND: It has been suggested that homosexuality is associated with psychiatric morbidity. This study examined differences between heterosexually and homosexually active subjects in 12-month and lifetime prevalence of DSM-III-R mood, anxiety, and substance use disorders in a representative sample of the Dutch population (N = 7076; aged 18-64 years). METHODS: Data were collected in face-to-face interviews, using the Composite International Diagnostic Interview. Classification as heterosexual or homosexual was based on reported sexual behavior in the preceding year. Five thousand nine hundred ninety-eight (84.8%) of the total sample could be classified: 2.8% of 2878 men and 1.4% of 3120 women had had same-sex partners. Differences in prevalence rates were tested by logistic regression analyses, controlling for demographics. RESULTS: Psychiatric disorders were more prevalent among homosexually active people compared with heterosexually active people. Homosexual men had a higher 12-month prevalence of mood disorders (odds ratio [OR] = 2.93; 95% confidence interval [CI] = 1.54-5.57) and anxiety disorders (OR = 2.61; 95% CI = 1.44-4.74) than heterosexual men. Homosexual women had a higher 12-month prevalence of substance use disorders (OR = 4.05; 95% CI = 1.56-10.47) than heterosexual women. Lifetime prevalence rates reflect identical differences, except for mood disorders, which were more frequently observed in homosexual than in heterosexual women (OR = 2.41; 95% CI = 1.26-4.63). The proportion of persons with 1 or more diagnoses differed only between homosexual and heterosexual women (lifetime OR = 2.61; 95% CI = 1. 31-5.19). More homosexual than heterosexual persons had 2 or more disorders during their lifetimes (homosexual men: OR = 2.70; 95% CI = 1.66-4.41; homosexual women: OR = 2.09; 95% CI = 1.07-4.09). CONCLUSION: The findings support the assumption that people with same-sex sexual behavior are at greater risk for psychiatric disorders.

Psychiatric and sociodemographic predictors of attrition in a longitudinal study: The Netherlands Mental Health Survey and Incidence Study (NEMESIS).

This article discusses the effects of sociodemographics and the presence of psychiatric disorders diagnosed in the 12 months before the first interview by using the Diagnostic and Statistical Manual of Mental Disorders: DSM-III-R, third edition, revised, on three types of attrition (failure to locate, refusal to participate, morbidity/mortality) in the second wave (1997-1998) of the Netherlands Mental Health Survey and Incidence Study, a longitudinal, general population survey of psychopathology among 7,076 subjects aged 18-64 years. Compared with those reinterviewed successfully, persons not located at the 1-year follow-up (n = 219) were more often younger, poorly educated, urban, not cohabiting with a steady partner, and born outside the Netherlands. Refusers (n = 923) had a lower educational level. Morbidity/mortality (n = 72) was associated with higher age, lower educational level, not being employed, and somatic disorders. After adjustment for sociodemographics, none of the disorders was positively associated with refusal. Failure to locate was linked to agoraphobia, alcohol abuse, and the categories of mood, substance use, and eating disorders. Morbidity/mortality was linked to dysthymia, agoraphobia, simple phobia, obsessive-compulsive disorder, and the category of anxiety disorders. Overall attrition was only slightly higher among respondents with one or more disorders (odds ratio = 1.20, 95% confidence interval: 1.04, 1.38). Thus, psychopathology has only weak-to-moderate effects on attrition and is mainly related to failure to locate and morbidity/mortality but not to refusal.