Mood, anxiety and psychotic phenomena measure a common psychopathological factor.

BACKGROUND: Psychotic phenomena are common in the general population but are excluded from diagnostic criteria for mild to moderate depression and anxiety despite their co-occurrence and shared risk factors. We used item response theory modelling to examine whether the co-occurrence of depressive, anxiety and psychotic phenomena is best explained by: (1) a single underlying factor; (2) two separate, uncorrelated factors; (3) two separate yet linked factors; or (4) two separate domains along with an underlying 'common mental distress' (CMD) factor. We defined where, along any latent continuum, the psychopathological items contributed most information. METHOD: We performed a secondary analysis of cross-sectional, item-level information from measures of depression, anxiety and psychotic experiences in 6617 participants aged 13 years from the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort and 977 participants aged 18 years from the ROOTS schools-based sample. We replicated results from one sample in the other and validated the latent factors against an earlier parental measure of mental state. RESULTS: In both cohorts depression, anxiety and psychotic items were best represented as a bi-factor model with a single, unitary CMD factor on which psychotic items conveyed information about the more severe end (model 4); residual variation remained for psychotic items. The CMD factor was significantly associated with the prior parental measure. CONCLUSIONS: Psychotic phenomena co-occur with depression and anxiety in teenagers and may be a marker of severity in a single, unitary dimension of CMD. Psychotic phenomena should be routinely included in epidemiological assessments of psychiatric morbidity, otherwise the most severe symptomatology remains unmeasured.

Factors of psychological distress: clinical value, measurement substance, and methodological artefacts.

PURPOSE: Psychometric models and statistical techniques are cornerstones of research into latent structures of specific psychopathology and general mental health. We discuss "pivot points" for future research efforts from a psychometric epidemiology perspective, emphasising sampling and selection processes of both indicators that guide data collection as well as samples that are confronted with them. METHOD: First, we discuss how a theoretical model of psychopathology determines which empirical indicators (questions, diagnoses, etc.) and modelling methods are appropriate to test its implications. Second, we deal with how different research designs introduce different (co-)variances between indicators, potentially leading to a different understanding of latent structures. Third, we discuss widening the range of statistical models available within the "psychometrics class": the inclusion of categorical approaches can help to enlighten the debate on the structure of psychopathology and agreement on a minimal set of models might lead to greater convergence between studies. Fourth, we deal with aspects of methodology that introduce spurious (co-)variance in latent structure analysis (response styles, clustered data) and differential item functioning to gather more detailed information and to guard against over-generalisation of results, which renders assessments unfair. CONCLUSIONS: Building on established insights, future research efforts should be more explicit about their theoretical understanding of psychopathology and how the analysis of a given indicator-respondent set informs this theoretical model. A coherent treatment of theoretical assumptions, indicators, and samples holds the key to building a comprehensive account of the latent structures of different types of psychopathology and mental health in general.

Lifetime affect and midlife cognitive function: prospective birth cohort study.

BACKGROUND: Recurrent affective problems are predictive of cognitive impairment, but the timing and directionality, and the nature of the cognitive impairment, are unclear. AIMS: To test prospective associations between life-course affective symptoms and cognitive function in late middle age. METHOD: A total of 1668 men and women were drawn from the Medical Research Council National Survey of Health and Development (the British 1946 birth cohort). Longitudinal affective symptoms spanning age 13-53 years served as predictors; outcomes consisted of self-reported memory problems at 60-64 years and decline in memory and information processing from age 53 to 60-64 years. RESULTS: Regression analyses revealed no clear pattern of association between longitudinal affective symptoms and decline in cognitive test scores, after adjusting for gender, childhood cognitive ability, education and midlife socioeconomic status. In contrast, affective symptoms were strongly, diffusely and independently associated with self-reported memory problems. CONCLUSIONS: Affective symptoms are more clearly associated with self-reported memory problems in late midlife than with objectively measured cognitive performance.

Early development, stress and depression across the life course: pathways to depression in a national British birth cohort.

BACKGROUND: The aetiology of depression is multifactorial, with biological, cognitive and environmental factors across the life course influencing risk of a depressive episode. There is inconsistent evidence linking early life development and later depression. The aim of this study was to investigate relationships between low birthweight (LBW), infant neurodevelopment, and acute and chronic stress as components in pathways to depression in adulthood. METHOD: The sample included 4627 members of the National Survey of Health and Development (NSHD; the 1946 British birth cohort). Weight at birth, age of developmental milestones, economic deprivation in early childhood, acute stressors in childhood and adulthood, and socio-economic status (SES) in adulthood were assessed for their direct and indirect effects on adolescent (ages 13 and 15 years) and adult (ages 36, 43 and 53 years) measures of depressive symptoms in a structural equation modelling (SEM) framework. A structural equation model developed to incorporate all variables exhibited excellent model fit according to several indices. RESULTS: The path of prediction from birthweight to age of developmental milestones to adolescent depression/anxiety to adult depression/anxiety was significant (p < 0.001). Notably, direct paths from birthweight (p = 0.25) and age of developmental milestones (p = 0.23) to adult depression were not significant. Childhood deprivation and stressors had important direct and indirect effects on depression. Stressors in adulthood were strongly associated with adult depression. CONCLUSIONS: Depression in adulthood is influenced by an accumulation of stressors across the life course, including many that originate in the first years of life. Effects of early-life development on mental health appear by adolescence.

Psychometric precision in phenotype definition is a useful step in molecular genetic investigation of psychiatric disorders.

Affective disorders are highly heritable, but few genetic risk variants have been consistently replicated in molecular genetic association studies. The common method of defining psychiatric phenotypes in molecular genetic research is either a summation of symptom scores or binary threshold score representing the risk of diagnosis. Psychometric latent variable methods can improve the precision of psychiatric phenotypes, especially when the data structure is not straightforward. Using data from the British 1946 birth cohort, we compared summary scores with psychometric modeling based on the General Health Questionnaire (GHQ-28) scale for affective symptoms in an association analysis of 27 candidate genes (249 single-nucleotide polymorphisms (SNPs)). The psychometric method utilized a bi-factor model that partitioned the phenotype variances into five orthogonal latent variable factors, in accordance with the multidimensional data structure of the GHQ-28 involving somatic, social, anxiety and depression domains. Results showed that, compared with the summation approach, the affective symptoms defined by the bi-factor psychometric model had a higher number of associated SNPs of larger effect sizes. These results suggest that psychometrically defined mental health phenotypes can reflect the dimensions of complex phenotypes better than summation scores, and therefore offer a useful approach in genetic association investigations.

Multilevel investigation of variation in HoNOS ratings by mental health professionals: a naturalistic study of consecutive referrals.

Episodes of mental healthcare in specialist psychiatric services often begin with the assessment of clinical and psychosocial needs of patients by healthcare professionals. Particularly for patients with complex needs or severe problems, ratings of clinical and social functioning at the start of each episode of care may serve as a baseline against which subsequent measures can be compared. Currently, little is known about service variations in such assessments on referrals from primary care. We set out to quantify variability in initial assessments performed by healthcare professionals in three CMHTs in Bristol (UK) using the Health of the Nation Outcome Scales (HoNOS). We tested the hypothesis that variations in HoNOS total and sub-scale scores are related to referral source (general practices), healthcare assessor (in CMHTs) and the assessor's professional group. Statistical analysis was performed using multilevel variance components models with cross-classified random effects. We found that variation due to assessor substantially exceeded that due to referral source (general practices). Furthermore, patient variance differed by assessor profession for the HoNOS--Impairment scores. Assessor variance differed by assessor profession for the HoNOS--Social scores. As HoNOS total and subscale scores show much larger variation by assessor than by referral source, investigations of HoNOS scores must take assessors into account. Services should implement and evaluate interdisciplinary training to improve consistency in use of rating thresholds; such initiatives could be evaluated using these extensions of multilevel models. Future research should aim to integrate routine diagnostic data with continuous outcomes to address selection effects (of patients to assessors) better.

General distress, hopelessness-suicidal ideation and worrying in adolescence: concurrent and predictive validity of a symptom-level bifactor model for clinical diagnoses.

BACKGROUND: Clinical disorders often share common symptoms and aetiological factors. Bifactor models acknowledge the role of an underlying general distress component and more specific sub-domains of psychopathology which specify the unique components of disorders over and above a general factor. METHODS: A bifactor model jointly calibrated data on subjective distress from The Mood and Feelings Questionnaire and the Revised Children's Manifest Anxiety Scale. The bifactor model encompassed a general distress factor, and specific factors for (a) hopelessness-suicidal ideation, (b) generalised worrying and (c) restlessness-fatigue at age 14 which were related to lifetime clinical diagnoses established by interviews at ages 14 (concurrent validity) and current diagnoses at 17 years (predictive validity) in a British population sample of 1159 adolescents. RESULTS: Diagnostic interviews confirmed the validity of a symptom-level bifactor model. The underlying general distress factor was a powerful but non-specific predictor of affective, anxiety and behaviour disorders. The specific factors for hopelessness-suicidal ideation and generalised worrying contributed to predictive specificity. Hopelessness-suicidal ideation predicted concurrent and future affective disorder; generalised worrying predicted concurrent and future anxiety, specifically concurrent generalised anxiety disorders. Generalised worrying was negatively associated with behaviour disorders. LIMITATIONS: The analyses of gender differences and the prediction of specific disorders was limited due to a low frequency of disorders other than depression. CONCLUSIONS: The bifactor model was able to differentiate concurrent and predict future clinical diagnoses. This can inform the development of targeted as well as non-specific interventions for prevention and treatment of different disorders.

The Nottingham Acute Bed Study: alternatives to acute psychiatric care.

BACKGROUND: Although modern psychiatric services seek alternatives to hospitalisation wherever appropriate, the national trend toward higher bed occupancies on acute psychiatric wards has refocused attention on community-based alternatives and methods of assessing reed for acute care. METHOD: We surveyed key decision makers in a community-oriented district service with a low acute psychiatric bed to population ratio, in order to examine alternatives to hospitalisation in a cohort of consecutive admissions over a six-month period. RESULTS: Alternatives to acute ward hospitalisation were identified for 29% of admissions, and for 42% of those with an admission duration of more than 60 days. Residential options were chosen more often than intensive community support. Simulated bed day savings were considerable. CONCLUSIONS: In a community-oriented service, key decision-makers could identify further alternatives to acute ward hospitalisation, although relatively few non-residential, community support options were chosen. Although this methodology has limitations, data based upon keyworker judgements probably have greater local 'ownership', and the option appraisal process itself may challenge stereotyped patterns of resource use.

Non-linear relationship between an index of social deprivation, psychiatric admission prevalence and the incidence of psychosis.

BACKGROUND: Indicators of population socio-economic disadvantage expressed as weighted deprivation indices show strong relationships with mental health and underpin national funding of psychiatric services. A new index of social deprivation, the Mental Illness Needs Index, has been devised specifically to predict need for psychiatric services. Its validity has not been established outside the area in which it was developed. METHODS: We explored the relationship between the Mental Illness Needs Index and two alternative indicators of need for mental health services: the prevalence of psychiatric admission for electoral wards in Nottingham (calculated from Hospital Episode Statistics for the years 1992 and 1993) and ward-based incidence rates for psychosis (ICD-10 F1X-F33). Relationships were explored graphically using local regression models, and estimated using Generalized Linear and Additive Models, and Poisson regression. RESULTS: Social deprivation was strongly related to admission prevalence and psychosis incidence (Spearman's rho 0.63 and 0.44 respectively). Neither admission prevalence, nor the incidence of psychosis were linearly related to social deprivation. Areas with above average social deprivation had both more new cases of psychoses and a higher proportion of the population admitted than expected from a linear function. CONCLUSIONS: Application of a linear function to funding gradients may underfund high and low need areas and overfund median need areas. Improving the precision of estimates of the relationship between social deprivation and need for services is crucial to more equitable resource allocation.

Educational consequences of mental disorders treated in hospital. A 31-year follow-up of the Northern Finland 1966 Birth Cohort.

BACKGROUND: Mental disorders often begin during the formative years of education. They may disrupt education and lead to social underachievement. METHODS: We examined the impact of mental disorders treated in hospital (ages 16-29) on educational attainment up to 31 years in the Northern Finland 1966 Birth Cohort (N = 10581). People discharged due to mental illness were grouped by DSM-III-R diagnoses (of schizophrenia, other psychoses and non-psychotic disorders) and were compared with those having no such hospital treatment. Associations between diagnoses and educational outcome (completion of basic level, upper secondary or tertiary education) were analysed stratified by age at onset (early onset < 22 years v. later), and adjusted for confounding by perinatal risk, early motor development, maternal education, family structure, parental social class, and school achievement using prospective data from earlier assessments and logistic regression analysis. RESULTS: Twelve per cent of the comparison group completed basic level education, 62% upper secondary, and 26% tertiary education. People with early onset disorder tended to stagnate in the basic level. Early onset schizophrenia and all non-psychotic cases had 3- to 6-fold adjusted odds for this outcome. Many with early onset schizophrenia completed secondary education, but none completed the tertiary level. Hospitalization for non-psychotic disorder increased the risk of underachievement in tertiary education for those with early onset. CONCLUSIONS: Mental disorder treated in hospital truncates education. Failure to complete higher education may contribute to the 'social exclusion' of the mentally ill through reduced opportunities in later occupational life and failure to accumulate social capital.

Effects of verbal working memory load on corticocortical connectivity modeled by path analysis of functional magnetic resonance imaging data.

We investigated the hypothesis that there are load-related changes in the integrated function of frontoparietal working memory networks. Functional magnetic resonance imaging time-series data from 10 healthy volunteers performing a graded n-back verbal working memory task were modeled using path analysis. Seven generically activated regions were included in the model: left/right middle frontal gyri (L/R MFG), left/right inferior frontal gyri (L/R IFG), left/right posterior parietal cortex (L/R PPC), and supplementary motor area (SMA). The model provided a good fit to the 1-back (chi(2) = 7.04, df = 8, P = 0.53) and 2-back conditions (chi(2) = 9.35, df = 8, P = 0.31) but not for the 3-back condition (chi(2) = 20.60, df = 8, P = 0.008). Model parameter estimates were compared overall among conditions: there was a significant difference overall between 1-back and 2-back conditions (chi(2)(diff) = 74.77, df = 20, P < 0.001) and also between 2-back and 3-back conditions (chi(2)(diff) = 96.28, df = 20, P < 0.001). Path coefficients between LIFG and LPPC were significantly different from zero in both 1-back and 2-back conditions; in the 2-back condition, additional paths from LIFG to LPPC via SMA and to RMFG from LMFG and LPPC were also nonzero. This study demonstrated a significant change in functional integration of a neurocognitive network for working memory as a correlate of increased load. Enhanced inferior frontoparietal and prefrontoprefrontal connectivity was observed as a correlate of increasing memory load, which may reflect greater demand for maintenance and executive processes, respectively.