Reappraisal of the interplay between psychosis and depression symptoms in the pathogenesis of psychotic syndromes: results from a twenty-year prospective community study

Testing extra-linearity across a psychosis continuum

BACKGROUND

It is unclear whether psychotic experiences (PEs) gradually merge into states of clinical psychosis along a continuum which correspond to a dimensional classification or whether latent classes appear above a certain severity threshold which correspond better to diagnostic categories of psychosis.

METHODS

Annual cross-sectional surveys, 2014-19, among Chinese undergraduates (N = 47,004) measured PEs, depression and etiological risk factors using standardized self-report instruments. We created a psychosis continuum with five levels and tested linear and extra-linear contrasts in associated etiological risk factors, before and after adjustment for depression. We carried out latent class analysis.

RESULTS

Categorical expression of psychosis, including hallucinations and delusions, nuclear symptoms, and nuclear symptoms and depression were found at severe level 5. Etiological risk factors which impacted linearly across the continuum were more common for depression. Child maltreatment impacted extra-linearly on both psychosis and depression. Family history of psychosis impacted linearly on psychosis; male sex and urban birth impacted extra-linearly and were specific for psychosis. Four latent classes were found, but only at level 5. These corresponded to nuclear schizophrenia symptoms, nuclear schizophrenia and depressive symptoms, severe depression, and an unclassified category with moderate prevalence of PEs.

CONCLUSION

Quantitative and qualitative changes in the underlying structure of psychosis were observed at the most severe level along a psychosis continuum, where four latent classes emerged. These corresponded to existing categorical classifications but require confirmation with clinical interview. PEs are non-specific and our findings suggest some are on a continuum with depression, whilst others are on a continuum with non-affective psychosis. Differing patterns of impact from etiological risk factors across the spectrum of psychopathology determine outcome at the most severe level of these continua.

Impact of urban birth and upbringing on expression of psychosis in a Chinese undergraduate population

BACKGROUND

Urban birth and upbringing show consistent associations with psychotic illness but the key urban exposures remain unknown. Associations with psychotic-like experiences (PEs) are inconsistent. These could be confounded by common mental disorders associated with PEs. Furthermore, associations between PEs and urban exposures may not extrapolate to psychotic disorders such as schizophrenia.

METHODS

Annual cross-sectional surveys among first year Chinese undergraduates 2014-2019 (n = 47,004). Self-reported, hierarchical categorisation of psychosis: from psychoticism, paranoid ideation, schizotypal symptoms, nuclear syndrome using SCL-90-R, to clinical diagnosis of schizophrenia. Depressive symptoms using PHQ 9. Dissociative symptoms and posttraumatic stress disorder (PTSD) measured using PCL-C. Etiological factors of family history and childhood disadvantage. We studied effects of urban birth, urban living and critical times of exposure in childhood on psychosis phenotypes.

RESULTS

Associations with urbanicity were found only after adjustments for depression. Urban birth was associated with paranoia (AOR 1.34, 1.18-1.53), schizotypal symptoms (AOR 1.59, 1.29-1.96), and schizophrenia (AOR 2.07, 1.10-3.87). The same phenotypes showed associations with urban residence > 10 years. Only schizophrenia showed an association with urban exposure birth-3 years (AOR 7.01, 1.90-25.86). Child maltreatment was associated with both psychosis and depression. Urbanicity measured across the total sample did not show any associations with demography, family history of psychosis, or child maltreatment. Sensitivity analysis additionally adjusting for dissociative symptoms and PTSD showed the same pattern of findings.

CONCLUSIONS

Urban birth and urban living showed a hierarchical pattern of increasing associations from paranoid ideation to schizotypal disorder to schizophrenia, confirming that associations for psychotic experiences could be extrapolated to schizophrenia, but only after adjusting for confounding from depression, dissociative symptoms and PTSD. Several etiological factors were the same for psychosis and depression. Future studies of PEs should adjust for confounding from common mental disorders and dissociative symptoms. Effects of urbanicity on psychosis were not explained by demography, family history of mental disorder, or child maltreatment.

Heritability and familiality of psychopathologic dimensions in Korean families with schizophrenia

AIM

Categorical syndromes such as schizophrenia could be a combination of many continuous mental structure phenotypes including several personality development/degeneration dimensions. This study investigated the heritability and familiality of symptom check list (SCL) psychopathologic dimensions in Korean schizophrenia linkage disequilibrium families.

METHOD

We recruited 204 probands (with schizophrenia) with their parents and siblings whenever possible. We used the SCL questionnaire to measure psychopathologic dimensions. The heritability of symptomatic dimensions in 543 family members was estimated using Sequential Oligogenic Linkage Analysis Routines (SOLAR). Psychopathologic dimensions in the 543 family members were compared with those in 307 healthy unrelated controls to measure familiality on using analysis of variance (ANOVA) analysis.

RESULTS

Five of the nine SCL variables were significantly heritable and were included in the subsequent analyses. The three groups (control, unaffected first-degree relative, schizophrenia patient) were found to be significantly different with regard to the expected order of average group scores for all heritable dimensions.

CONCLUSION

Aberrations in several symptomatic dimensions could contribute to the complexity of schizophrenia syndrome as a result of genetic-environment coaction or interaction in spite of some limitations (recruited family, phenotyping).

Factor structure models of the SCL-90-R: Replicability across community samples of adolescents

Derogatis' Symptom Checklist-90-Revised (SCL-90-R) is one of the most widely used measures of psychological distress in both the clinical and the research settings, although its factor structure is still debated. In this study, the factor structure of the SCL-90-R has been investigated in two independent samples of Italian adolescents. Two samples of 817 (urban sample) and 507 (rural sample) adolescents attending high schools were involved. Confirmatory factorial analysis (CFA) was used alongside hierarchical nested, progressively constrained models to assess configural, metric and scalar invariance of the best models fitted by CFA. The standard nine-factor structure of the SCL-90-R resulted reproducible and invariant between the two samples, in both its correlated and hierarchical second-order implementations. Estimated reliability of the nine scales of the SCL-90-R was optimal. This study also confirmed the reproducibility of the bifactor models of the SCL-90-R with nine orthogonally independent factors and with nine correlated primary factors, which have been tested in some recent studies. Overall, the SCL-90-R measures both common and unique features of psychological distress in community samples. The measurement invariance across different levels of psychological distress in the factor structure of the SCL-90-R is an issue deserving further testing and investigation.

The Intricate Relationship between Psychotic-Like Experiences and Associated Subclinical Symptoms in Healthy Individuals

The interplay between subclinical psychotic, negative, and affective symptoms has gained increased attention regarding the etiology of psychosis spectrum and other mental disorders. Importantly, research has tended to not differentiate between different subtypes of psychotic-like experiences (PLE) although they may not have the same significance for mental health. In order to gain information on the subclinical interplay between specific PLE and other symptoms as well as the significance of PLE for mental health, we investigated their specific associations in 206 healthy individuals (20-60 years, 73 females) using correlational and linear regression analyses. PLE were assessed with the Magical Ideation Questionnaire, the revised Exceptional Experiences Questionnaire, and subscales of the Schizotypal Personality Questionnaire (SPQ). The revised Symptom Checklist 90, the SPQ, and the Physical Anhedonia Scale were used to measure subclinical negative symptoms, affective symptoms, and other symptoms such as, emotional instability. As hypothesized, we found that (1) most affective symptoms and all other subclinical symptoms correlated positively with all PLE, whereas we found only partial associations between negative symptoms and PLE. Notably, (2) magical ideation and paranormal beliefs correlated negatively with physical anhedonia. In the regression analyses we found (3) similar patterns of specific positive associations between PLE and other subclinical symptoms: Suspiciousness was a specific predictor of negative-like symptoms, whereas ideas of reference, unusual perceptual experiences, and dissociative anomalous perceptions specifically predicted anxiety symptoms. Interestingly, (4) ideas of reference negatively predicted physical anhedonia. Similarly, paranormal beliefs were negatively associated with constricted affect. Moreover, odd beliefs were a negative predictor of depression, emotional instability, and unspecific symptoms. Our findings indicated that subtypes of PLE are differentially implicated in psychological functioning and should therefore not be categorized homogeneously. Moreover, paranormal beliefs, odd beliefs, and partly ideas of reference might also contribute to subjective well being in healthy individuals. Our results might serve as a starting point for longitudinal studies investigating the interplay of subtypes of subclinical symptoms along a psychopathological trajectory leading to mental disorders. Importantly, this research might help to improve therapeutic strategies for psychosis prevention.

Psychopathology in Substance Use Disorder Patients with and without Substance-Induced Psychosis

Background. Substance-induced psychotic disorder (SIPD) is a diagnosis constructed to distinguish substance-induced psychotic states from primary psychotic disorders. A number of studies have compared SIPD persons with primary psychotic patients, but there is little data on what differentiates substance use disorder (SUD) individuals with and without SIPD. Here, we compared psychopathology, sociodemographic variables, and substance use characteristics between SUD patients with and without SIPD. Methods. A retrospective chart review was conducted on newly admitted patients at a rehabilitation centre between 2007 and 2012. Results. Of the 379 patients included in the study, 5% were diagnosed with SIPD (n = 19) and 95% were diagnosed with SUDs without SIPD (n = 360). More SIPD patients reported using cannabis and psychostimulants, and fewer SIPD patients reported using alcohol than SUDs patients without SIPD. SIPD patients scored higher on the “schizophrenia nuclear symptoms” dimension of the SCL-90R psychoticism scale and exhibited more ClusterB personality traits than SUD patients without SIPD. Discussion. These data are consistent with previous studies suggesting that psychopathology, substance type, and sociodemographic variables play important role in the development of SIPD. More importantly, the results highlight the need for paying greater attention to the types of self-reported psychotic symptoms during the assessment of psychotomimetic effects associated with psychoactive substances.

Early Recognition of High Risk of Bipolar Disorder and Psychosis: An Overview of the ZInEP "Early Recognition" Study

Early detection of persons with first signs of emerging psychosis is regarded as a promising strategy to reduce the burden of the disease. In recent years, there has been increasing interest in early detection of psychosis and bipolar disorders, with a clear need for sufficient sample sizes in prospective research. The underlying brain network disturbances in individuals at risk or with a prodrome are complex and yet not well known. This paper provides the rationale and design of a prospective longitudinal study focused on at-risk states of psychosis and bipolar disorder. The study is carried out within the context of the Zurich Program for Sustainable Development of Mental Health services (Zürcher Impulsprogramm zur Nachhaltigen Entwicklung der Psychiatrie). Persons at risk for psychosis or bipolar disorder between 13 and 35 years of age are examined by using a multi-level-approach (psychopathology, neuropsychology, genetics, electrophysiology, sociophysiology, magnetic resonance imaging, near-infrared spectroscopy). The included adolescents and young adults have four follow-ups at 6, 12, 24, and 36 months. This approach provides data for a better understanding of the relevant mechanisms involved in the onset of psychosis and bipolar disorder, which can serve as targets for future interventions. But for daily clinical practice a practicable “early recognition” approach is required. The results of this study will be useful to identify the strongest predictors and to delineate a prediction model.

Sex differences in sub-clinical psychosis--results from a community study over 30 years

Sex differences in schizophrenia have long been reported. They are found within almost all aspects of the disease, from incidence and prevalence, age of onset, symptomatology, and course to its psycho-social outcome. Many sex-related hypotheses have been developed about the biology, psychology, or sociology of that disease. A further approach to study sex differences would be to examine such differences in sub-clinical psychotic states as well. If factors related to full-blown psychosis were equally meaningful over the entire psychosis continuum, we should expect that "true" sex differences could also be identified in sub-clinical psychosis. Here, we studied sex differences in sub-clinical psychosis within a community cohort in Zurich, Switzerland. This population was followed for over 30 years and included males and females between the ages of 20/21 and 49/50. We applied two different measures of sub-clinical psychosis representing schizotypal signs and schizophrenia nuclear symptoms. Using cross-sectional and longitudinal analyses, we found no significant sex differences in sub-clinical psychosis over time with respect to age of onset, symptomatology, course, or psycho-social outcome. Thus it appears that sex differences in psychosis manifest themselves at the high end of the continuum (full-blown schizophrenia) rather than within the sub-threshold range. Possibly males and females have separate thresholds for certain symptoms because they are differently vulnerable or exposed to various risk factors.

Linking substance use with symptoms of subclinical psychosis in a community cohort over 30 years

AIMS

The aim of the study was to examine the temporal associations between substance use and subclinical psychosis symptoms.

DESIGN

Data from a prospective community study sampled within a single cohort over 30 years (1978-2008) were analysed with discrete-time hazard models.

SETTING

General population-based sample.

PARTICIPANTS

At initial sampling in 1978 males (n = 292) were 19 and females (n = 299) were 20 years old.

MEASUREMENTS

Two psychosis syndromes representing 'schizotypal signs' and 'schizophrenia nuclear symptoms' and various substance use variables including cannabis, alcohol, tobacco and multiple-drug use (i.e. cannabis combined with other drugs).

FINDINGS

In bivariate analyses, schizotypal signs were predominantly associated with regular cannabis use in adolescence (OR = 2.29, 95% CI 1.32-3.97). Schizophrenia nuclear symptoms were mainly related to alcohol (OR = 1.84, 95% CI 1.00-3.38) and multiple-drug use (OR = 2.35, 95% CI 1.38-4.02) during adolescence. Multivariate analyses showed that, in particular, regular cannabis use during adolescence was associated with the occurrence of subsequent schizotypal symptoms over a 30-year period (OR = 2.60, 95% CI; 1.59-4.23), whereas multiple-drug use in adolescence was associated predominantly with schizophrenia nuclear symptoms (OR = 1.75, 95% CI 1.01-3.03). Alcohol misuse was only slightly associated with the onset of such symptoms.

CONCLUSIONS

A significant portion of the occurrence of subclinical psychosis symptoms in adulthood can be attributed to excessive cannabis and multiple-drug use during adolescence. This is in line with the hypothesis that long-term sensitization of dopaminergic brain receptors plays a role in developing psychotic symptoms.

Subjective emotional over-arousal to neutral social scenes in paranoid schizophrenia

From the clinical practice and some experimental studies, it is apparent that paranoid schizophrenia patients tend to assign emotional salience to neutral social stimuli. This aberrant cognitive bias has been conceptualized to result from increased emotional arousal, but direct empirical data are scarce. The aim of the present study was to quantify the subjective emotional arousal (SEA) evoked by emotionally non-salient (neutral) compared to emotionally salient (negative) social stimuli in schizophrenia patients and healthy controls. Thirty male inpatients with paranoid schizophrenia psychosis and 30 demographically matched healthy controls rated their level of SEA in response to neutral and negative social scenes from the International Affective Picture System and the Munich Affective Picture System. Schizophrenia patients compared to healthy controls had an increased overall SEA level. This relatively higher SEA was evoked only by the neutral but not by the negative social scenes. To our knowledge, the present study is the first designed to directly demonstrate subjective emotional over-arousal to neutral social scenes in paranoid schizophrenia. This finding might explain previous clinical and experimental data and could be viewed as the missing link between the primary neurobiological and secondary psychological mechanisms of paranoid psychotic-symptom formation. Furthermore, despite being very short and easy to perform, the task we used appeared to be sensitive enough to reveal emotional dysregulation, in terms of emotional disinhibition/hyperactivation in paranoid schizophrenia patients. Thus, it could have further research and clinical applications, including as a neurobehavioral probe for imaging studies.

Sub-clinical psychosis symptoms in young adults are risk factors for subsequent common mental disorders

BACKGROUND

Not all persons identified in the early stages to be at risk for psychosis eventually cross the threshold for a psychotic illness. However, sub-clinical symptoms may not only indicate a specific risk but also suggest a more general, underlying psychopathology that predisposes one to various common mental disorders.

METHODS

Analyzing data from the prospective Zurich Cohort Study, we used two psychosis subscales - "schizotypal signs" and "schizophrenia nuclear symptoms" - derived from the SCL-90-R checklist that measured sub-clinical psychosis symptoms in 1979. We also assessed 10 different diagnoses of common mental disorders through seven interview waves between 1979 and 2008. This 30-year span, covering participant ages of 19/20 to 49/50, encompasses the period of highest risk for the occurrence of such disorders.

RESULTS

Both psychosis scales from 1979, but especially "schizotypal signs", were significantly correlated with most mental disorders over the subsequent test period. Higher values on both subscales were associated with an increasing number of co-occurring disorders.

CONCLUSIONS

Our data demonstrate that sub-clinical psychosis generally represents a risk factor for the development of common mental disorders and a liability for co-occurring disorders. This refers in particular to dysthymia, bipolar disorder, social phobia, and obsessive-compulsive disorder. Proneness to psychosis could signal a fundamental tendency toward common mental disorders.

Magnitude, impact, and stability of primary headache subtypes: 30 year prospective Swiss cohort study

OBJECTIVE

To determine the prevalence, impact, and stability of different subtypes of headache in a 30 year prospective follow-up study of a general population sample.

DESIGN

Prospective cohort study.

SETTING

Canton of Zurich, Switzerland.

PARTICIPANTS

591 people aged 19-20 from a cohort of 4547 residents of Zurich, Switzerland, interviewed seven times across 30 years of follow-up.

MAIN OUTCOME MEASURES

Prevalence of headache; stability of the predominant subtype of headache over time; and age of onset, severity, impact, family history, use of healthcare services, and drugs for headache subtypes.

RESULTS

The average one year prevalences of subtypes of headache were 0.9% (female:male ratio of 2.8) for migraine with aura, 10.9% (female:male ratio of 2.2) for migraine without aura, and 11.5% (female:male ratio of 1.2) for tension-type headache. Cumulative 30 year prevalences of headache subtypes were 3.0% for migraine with aura, 36.0% for migraine without aura, and 29.3% for tension-type headache. Despite the high prevalence of migraine without aura, most cases were transient and only about 20% continued to have migraine for more than half of the follow-up period. 69% of participants with migraine and 58% of those with tension-type headache manifested the same predominant subtype over time. However, the prospective stability of the predominant headache subtypes was quite low, with substantial crossover among the subtypes and no specific ordinal pattern of progression. A gradient of severity of clinical correlates and service use was present across headache subtypes; the greatest effect was for migraine with aura followed by migraine without aura, and then tension-type headache and unclassified headaches.

CONCLUSIONS

These findings highlight the importance of prospective follow-up of people with headache. The substantial longitudinal overlap among subtypes of headache shows the developmental heterogeneity of headache syndromes. Studies of the causes of headache that apply diagnostic nomenclature based on distinctions between discrete headache subtypes may not capture the true nature of headache in the general population.

Exploratory Factor Analysis of SCL90-R Symptoms Relevant to Psychosis

OBJECTIVE

Inconsistent results have been reported regarding the symptom dimensions relevant to psychosis in symptoms check list revised (SCL90-R), i.e., "psychoticism" and "paranoid ideation". Therefore, some studies have suggested different factor structures for questions of these two dimensions, and proposed two newly defined dimensions of "schizotypal signs" and "schizophrenia nuclear symptoms". We conducted an exploratory factor analysis on the items of these two dimensions in a general population sample in Iran.

METHOD

A total of 2158 subjects residing in Southern Tehran (capital of Iran) were interviewed using the psychoticism and paranoid ideation questions in SCL90-R to assess severity of these symptom dimensions. Factor analysis was done through SAS 9.1.3 PROC FACTOR using Promax rotation (power=3) on the matrix of "polychoric correlations among variables" as the input data.

RESULTS

Two factors were retained by the proportion criterion. Considering loadings >= 0.5 as minimum criteria for factor loadings, 7 out of 10 questions from psychoticism, and 3 out of 6 questions from paranoid ideation were retained, and others were eliminated. The factor labels proposed by the questionnaire suited the extracted factors and were retained. Internal consistency for each of the dimensions was acceptable (Cronbach's alpha 0.7 and 0.74 for paranoid ideation and psychoticism respectively). Composite scores showed a half-normal distribution for both dimensions which is predictable for instruments that detect psychotic symptoms.

CONCLUSION

Results were in contrast with similar studies, and questioned them by suggesting a different factor structure obtained from a statistically large population. The population in a developing nation (Iran) in this study and the socio-cultural differences in developed settings are the potential sources for discrepancies between this analysis and previous reports.