The case-control study in psychiatry

ICD-11 'mixed depressive and anxiety disorder' is clinical rather than sub-clinical and more common than anxiety and depression in the general population

Background

The new International Classification of Diseases was published in 2018 (ICD‐11; World Health Organization, 2018) and now includes ‘Mixed depressive and anxiety disorder’ (6A73: MDAD) designated as a mood disorder. This disorder is defined by symptoms of both anxiety and depression occurring more days than not, for a period of two weeks, and neither set of symptoms considered separately reaches a diagnostic threshold for either disorder. However, to date no study has examined the validity of these guidelines in a general population sample.

Methods

Using Goldberg et al.’s (2017) guidelines regarding measurement of depression and anxiety, this study used factor mixture modelling (FMM) to examine the validity of the ICD‐11 criteria of MDAD. Symptom endorsement rates are provided as well as demographic predictors and somatization outcomes.

Results

Fit indices suggested the two‐factor four‐class solution was the best balance between model complexity and model fit. The results did not support a class that is subsyndromal to both anxiety and depression. On the contrary, we suggest that there exists a ‘Comorbid’ class that represents endorsement of both anxiety and depression symptoms at a higher level when compared to both ‘anxiety’ and ‘depression’ groups. Demographic predictors, as well as somatization and functional impairment outcomes, provided support for this FMM solution.

Conclusions

The ‘Comorbid’ group was the largest symptomatic group and had the highest levels of both anxiety and depression symptoms. Importantly, this group was larger than either the ‘anxiety’ or ‘depression’ group and was associated with high levels of functional impairment and somatization.

The progression of disorder-specific brain pattern expression in schizophrenia over 9 years

Age plays a crucial role in the performance of schizophrenia vs. controls (SZ-HC) neuroimaging-based machine learning (ML) models as the accuracy of identifying first-episode psychosis from controls is poor compared to chronic patients. Resolving whether this finding reflects longitudinal progression in a disorder-specific brain pattern or a systematic but non-disorder-specific deviation from a normal brain aging (BA) trajectory in schizophrenia would help the clinical translation of diagnostic ML models. We trained two ML models on structural MRI data: an SZ-HC model based on 70 schizophrenia patients and 74 controls and a BA model (based on 561 healthy individuals, age range = 66 years). We then investigated the two models’ predictions in the naturalistic longitudinal Northern Finland Birth Cohort 1966 (NFBC1966) following 29 schizophrenia and 61 controls for nine years. The SZ-HC model’s schizophrenia-specificity was further assessed by utilizing independent validation (62 schizophrenia, 95 controls) and depression samples (203 depression, 203 controls). We found better performance at the NFBC1966 follow-up (sensitivity = 75.9%, specificity = 83.6%) compared to the baseline (sensitivity = 58.6%, specificity = 86.9%). This finding resulted from progression in disorder-specific pattern expression in schizophrenia and was not explained by concomitant acceleration of brain aging. The disorder-specific pattern’s progression reflected longitudinal changes in cognition, outcomes, and local brain changes, while BA captured treatment-related and global brain alterations. The SZ-HC model was also generalizable to independent schizophrenia validation samples but classified depression as control subjects. Our research underlines the importance of taking account of longitudinal progression in a disorder-specific pattern in schizophrenia when developing ML classifiers for different age groups.

Towards precise resting-state fMRI biomarkers in psychiatry: synthesizing developments in transdiagnostic research, dimensional models of psychopathology, and normative neurodevelopment

Searching for biomarkers has been a chief pursuit of the field of psychiatry. Toward this end, studies have catalogued candidate resting-state biomarkers in nearly all forms of mental disorder. However, it is becoming increasingly clear that these biomarkers lack specificity, limiting their capacity to yield clinical impact. We discuss three avenues of research that are overcoming this limitation: (i) the adoption of transdiagnostic research designs, which involve studying and explicitly comparing multiple disorders from distinct diagnostic axes of psychiatry; (ii) dimensional models of psychopathology that map the full spectrum of symptomatology and that cut across traditional disorder boundaries; and (iii) modeling individuals' unique functional connectomes throughout development. We provide a framework for tying these subfields together that draws on tools from machine learning and network science.

Exposure to Traumatic Events and Development of Psychotic Symptoms in a Prison Population: A Network Analysis Approach

Previous studies consistently observed an association between exposure to traumatic events and psychotic symptoms. However, little is known about the differential impact of distinct traumatic events and the role of general symptoms in mediating this relationship. Thus, our study aimed to explore the differential association of several traumatic events to the psychotic symptoms in a sample of prisoners and whether this association is mediated by general symptoms. The total sample from the Survey of Psychiatric Morbidity Among Prisoners in England and Wales (N = 3039; 75.4% male) was used. Participants completed a list of traumatic events experienced before reclusion, the Psychosis Screening Questionnaire, Clinical Review Schedule-Revised. Network analysis was used to estimate the network of interactions between traumatic events and general and psychotic symptoms. Shortest paths analysis was performed to identify the different development trajectories. Results suggested that memory problems, compulsions, and irritability might be key mediating symptoms for most traumatic events. However, sexual abuse showed alternative mediators that might be specific of this traumatic event. Finally, the traumatic events, suffered from violence at work, separation/divorce and been homeless showed direct associations with specific psychotic symptoms.

The Roles of Socioeconomic Status, Occupational Health and Job Rank on the Epidemiology of Different Psychiatric Symptoms in a Sample of UK Workers

There is a considerable gap in epidemiological literature about community mental health showing how psychiatric symptoms are associated with job rank, socioeconomic status, and occupational health. We examine data from 4596 employees collected in the United Kingdom's Psychiatric Morbidity among Adults Living in Private Households Survey. There were 939 workers in managerial jobs, 739 in supervisory jobs and 2918 employees in lower ranking jobs. Of the 4596 workers, 2463 had depressive symptoms and 2133 no depressive symptoms. Job rank, household gross income, social class, personal gross income and socio-economic group were significantly associated with general health, occupational health and depressive and avoidant symptoms. Job rank, occupational and physical health also explained the variance in paranoid and avoidant symptoms among the employees. This study shows that severe psychopathology is related to workers' job rank.

Variation in the recall of socially rewarding information and depressive symptom severity: a prospective cohort study

OBJECTIVE

To test the association between recall for socially rewarding (positive) and/or socially critical (negative) information and depressive symptoms.

METHOD

Cohort study of people who had visited UK primary care in the past year reporting depressive symptoms (N = 558, 69% female). Positive and negative recall was assessed at three time-points, 2 weeks apart, using a computerised task. Depressive symptoms were assessed at four time-points using the Beck Depression Inventory (BDI). Analyses were conducted using multilevel models.

RESULTS

Concurrently we found evidence that, for every increase in two positive words recalled, depressive symptoms reduced by 0.6 (95% CI -1.0 to -0.2) BDI points. This association was not affected by adjustment for confounders. There was no evidence of an association between negative recall and depressive symptoms (-0.1, 95% CI -0.5 to 0.3). Longitudinally, we found more evidence that positive recall was associated with reduced depressive symptoms than vice versa.

CONCLUSION

People with more severe depressive symptoms recall less positive information, even if their recall of negative information is unaltered. Clinicians could put more emphasis on encouraging patients to recall positive, socially rewarding information, rather than trying to change negative interpretations of events that have already occurred.

Bias in psychiatric case-control studies: literature survey

BACKGROUND

Case-control studies are vulnerable to selection and information biases which may generate misleading findings.

AIMS

To assess the quality of methodological reporting of case-control studies published in general psychiatric journals.

METHOD

All the case-control studies published over a 2-year period in the six general psychiatric journals with impact factors of more than 3 were assessed by a group of psychiatrists with training in epidemiology using a structured assessment devised for the purpose. The measured study quality was compared across type of exposure and journal.

RESULTS

The reporting of methods in the 408 identified papers was generally poor, with basic information about recruitment of participants often absent. Reduction of selection bias was described best in the "pencil and paper" studies and worst in the genetic studies. Neuroimaging studies reported the most safeguards against information bias. Measurement of exposure was reported least well in studies determining the exposure with a biological test.

CONCLUSIONS

Poor reporting of recruitment strategies threatens the validity of reported results and reduces the generalisability of studies.

Manic depressive illness and tyrosine hydroxylase gene: linkage heterogeneity and association

Several studies have implicated the tyrosine hydroxylase (TH) locus within the 11p15 region in susceptibility to manic depressive illness (MDI). This possibility was further investigated by both parametric (lod score) and nonparametric (affected-pedigree-member and a case-control study) methods of analysis in 11 French MDI families and in a sample of 200 unrelated subjects. Both types of analyses corroborate the implication of this locus, and positive lod scores were obtained in two families, which most likely reflects genetic heterogeneity. Statistical analyses were also performed including available data from published reports. These analyses, which allowed for genetic heterogeneity, substantiated our findings. The combined maximum lod score for all the families studied was 3.68 at theta = 0.00 (number of families: 36) assuming heterogeneity (alpha = 15%, P = 0.01). Taken together these results converge to suggest that the risk factors for MDI lie in the 11p15 region with TH being the most likely candidate gene.

Background factors in patients with schizoaffective disorder as compared with patients with diabetes and healthy individuals

Family history and psychosocial background factors were studied in married patients with a DSM-III diagnosis of schizoaffective disorder (n = 17, partners n = 16), married patients with diabetes (n = 10, partners n = 10) and married healthy individuals (n = 8, partners n = 8). The two latter groups were comparison control groups matched for gender and age to the patients with schizoaffective disorder. Affective disorder, not particularly schizoaffective disorder, was more common in first- and tended to be more common in second-degree relatives of patients with schizoaffective disorder as compared with controls. Poor parental relations, especially to the father, during the formative years were prominent in patients with schizoaffective disorder as compared with the controls. The same patients also more often than others gave a report of sexual encroachment, inside or outside the family, and corporal punishment during the growing-up years.

Disruptions in childhood parental care as risk factors for major depression in adult women

OBJECTIVE

The aim of this study was to examine the influence of different types of disruptions in childhood parental care before the age of 15 years as risk factors for major depression in women aged 18 to 44 years. The types of disruptions studied were parental death, parental separation or divorce, other types of loss (i.e. adoption, foster-care, etc.), and prolonged separation from both parents. Potential confounding factors were also examined.

METHOD

The data were obtained from a community probability sample. Caseness was determined by the use of the Diagnostic Interview Schedule (DIS) and both the current (one month) and lifetime prevalence periods were considered. Logistic regression was used to model the influence of each factor, singly and adjusted for the influence of other factors, on the risk for major depression.

RESULTS

It was found that in this population 17% had experienced some type of parental loss (parental death 4%, separations/divorce 10% and other types of loss 3%) and 11% had experienced prolonged separation from both parents. Parental loss was significantly associated with lifetime depression, but this effect was no longer significant when adjusted for other factors. However, prolonged separation from both parents was associated with an increased risk of current and lifetime depressive episodes of approximately three to fourfold, even when the risk was adjusted for other factors.

CONCLUSIONS

The results of this study suggest that prolonged separation from both parents has a stronger association with current or lifetime depression in women than do parental death, separation/divorce and other types of loss. Prolonged separation may be a marker for other risk factors and may not be a risk factor on its own.

The social network of patients with schizoaffective disorder as compared to healthy individuals

The social network was evaluated by means of the self-rating scale 'Interview Schedule for Social Interaction' (ISSI) and semi-structured interviews in married patients with a DSM-III diagnosis of schizoaffective disorder (N = 17, partners, N = 16), married patients with diabetes (N = 10, partners, N = 10) and in married healthy individuals (N = 8, partners, N = 8). The two latter groups were comparison control groups matched for sex and age to the patients with a schizoaffective disorder. The scores on the ISSI and its subscales for the groups were compatible to those found in other Swedish studies. Patients with a schizoaffective disorder both experienced that they had less access to (AVAT) and were less satisfied with their deep emotional relations (ADAT). The same patients had a higher level of neuroticism as compared to the rest. The patients with a schizoaffective disorder had less often than the patients with diabetes been informed about their disease. Moreover, the partners to the patients with a schizoaffective disorder had not been informed about the disease and experienced that they had fewer social contacts (AVSI). A challenge for the professional network in psychiatry is to improve the information and education to families in which one member is struck by a schizoaffective disorder.

Cerebral ventricle dimensions as risk factors for schizophrenia and affective psychosis: an epidemiological approach to analysis

A case-control study was undertaken of volumetric computerized tomographic scan measures in 216 consecutive admissions for functional psychosis and 67 healthy community controls. Odds ratio analysis demonstrated significant linear trends in the association between increasing lateral and third ventricle volumes, and both RDC schizophrenia (N = 121) and schizo-affective disorder (N = 41); cases were consistently associated with larger volumes than controls. There was an association between larger third, but not lateral, ventricle size in affective psychoses (N = 54). These associations were statistically independent of intracranial volume, sex, social class and ethnicity, factors which were significantly associated with ventricular measures in the controls. There was no evidence of a threshold corresponding to the notion of normal versus enlarged ventricles. Within the schizophrenia group, there were no large or significant associations between ventricle dimensions and age at onset, duration of illness or pre-morbid social functioning. Neither obstetric complications nor a family history of schizophrenia or other psychiatric illness was associated with large ventricles in these cases.

A community survey of psychotropic drug consumption in South Verona: prevalence and associated variables

A cross-sectional community survey was undertaken to investigate the pattern of psychotropic drug consumption in 453 community residents of South Verona. Overall, 15.0% of the subjects were taking psychotropics (benzodiazepines 13.5%, antidepressants 2.2%, neuroleptics 1.1%). Prevalence was higher in females (20.0%), in those over 45 years (25%), in high General Health Questionnaire (GHQ) scorers (26.2%), and in subjects with physical ill-health (27.0%), with social problems (20.0%), with distressing events (22.0%) and with alcohol abuse (32.3%). Logistic regression analysis showed that age, sex, GHQ score, physical ill-health and life events were all significantly and independently associated with psychotropic drug consumption.

Measuring psychiatric disorder in the community: a standardized assessment for use by lay interviewers

Many of the standardized interviews currently used in psychiatry require the interviewer to use expert psychiatric judgements in deciding upon the presence or absence of psychopathology. However, when case definitions are standardized it is customary for clinical judgements to be replaced with rules. The Clinical Interview Schedule was therefore revised, in order to increase standardization, and to make it suitable for use by 'lay' interviewers in assessing minor psychiatric disorder in community, general hospital, occupational and primary care research. Two reliability studies of the revised Clinical Interview Schedule (CIS-R) were conducted in primary health care clinics in London and Santiago, Chile. Both studies compared psychiatrically trained interviewer(s) with lay interviewer(s). Estimates of the reliability of the CIS-R compared favourably with the results of studies of other standardized interviews. In addition, the lay interviewers were as reliable as the psychiatrists and did not show any bias in their use of the CIS-R. Confirmatory factor analysis models were also used to estimate the reliabilities of the CIS-R and self-administered questionnaires and indicated that traditional measures of reliability are probably overestimates.