Incidence of depressive syndromes in a Danish county. The Aarhus County investigation

Epidémiologie de la dépression: données récentes. II — Epidémiologie analytique et épidémiologie d’évaluation

Les données provenant d’études récentes concernant l’épidémiologie analytique et l’épidémiologie d’évauation de la dépression sont examinées.

Au sujet de l’épidémiologie analytique, il peut être conclu de la littérature actuellement disponible que les principaux facteurs de risques pour la dépression majeure sont : a) Sociodémographiques, à savoir : être une femme, être jeune, séparé, divorcé, ou avoir des problèmes conjugaux (les auteurs soulignent en particulier que les différences entre les sexes, concernant la dépression, sont réelles et ne sont pas un artefact lié à la façon de relater les troubles ou au comportement vis-à-vis des soins), b) Environnementaux: facteurs prédisposants (les événements de vie qui surviennent durant l'enfance peuvent prédisposer un individu à la dépression à l’âge adulte) et facteurs précipitants (il y a relation entre la survenue d’événements de vie pendant la vie adulte et le début de la dépression), c) Familiaux: il y a une multiblication par 2 à 5 du taux de dépression majeure chez les parents de premier degré de sujets témoins par rapport à es témoins non malades. L’influence de l’hérédité génétique est supportée par des études de jumeaux et des études adoption, mais une large part de la variance ne peut être expliquée, d) Divers: qui concernent le cycle de reproduc- 10n de la femme (la période du post partum entraîne une augmentation du taux de dépression) et les variations saisonneres (pics au printemps et en automne).

En ce qui concerne l'épidémiologie d’évaluation, il est habituel de distinguer prévention primaire, secondaire et teriaie. Leur dessein est respectivement de diminuer l’incidence de la dépression, la prévalence de la dépression et les isques de chronicité et de la récurrence. Les efforts concernant la prévention primaire ne peuvent avoir qu’un effet imité. Dans le domaine de la prévention secondaire, il peut être conclu que beaucoup de dépressifs ne sont pas diaglostiqués ou ne sont pas traités. La prévention tertiaire a pour dessein de limiter deux risques: la chronicité et la récurence. Le premier pourrait être évalué à 15-20% à chaque épisode. Les facteurs de risques principaux seraient la présence un trouble psychiatrique non affectif ou d’une affection physique, une personnalité névrotique et un faible niveau le traitement. Pour le risque de récurrence, on peut considérer qu’entre 50 et 85% des patients ayant fait un épisode lépressif majeur feront au moins un autre épisode de dépression ultérieurement. Les facteurs de risques pourraient re un Stand nombre d’épisodes antérieurs, un antécédent d’épisode maniaque ou d’hypomanie, l’association à un ésordre psychiatrique non affectif ou à une affection physique, une histoire familiale de maladie affective ou un âge e début tardif.

Seasonal variations in hospital admissions for mania: Examining for associations with weather variables over time

BACKGROUND

Bipolar disorder is characterized by a seasonal pattern with emerging evidence that weather conditions may trigger symptoms. Thus, our aims were to investigate if year-to-year variations in admissions with mania correlated with year-to-year variations in key meteorological variables, if there was a secular trend in light of climate change and if gender or admission status influenced the seasonal pattern.

METHODS

We undertook a Danish register-based nationwide historical cohort study. We included all adults hospitalized to psychiatric care from 1995 to 2012 with mania using the Danish Psychiatric Central Research Register. The Danish Meteorological Institute provided the meteorological variables. The association between weather and admissions was tested using linear regression.

RESULTS

Our database comprised 24,313 admissions with mania. There was a seasonal pattern with admission rates peaking in summer. Higher admission rates were associated with more sunshine, more ultraviolet radiation, higher temperature and less snow but were unassociated with rainfall. We did not find a secular trend in the seasonal pattern. Finally, neither gender nor admission status impacted on the overall seasonal pattern of admissions with mania.

LIMITATIONS

Only patients in psychiatric care were included. We could not subdivide by type of bipolar disorder.

CONCLUSION

This cohort study based on more than 24,000 admissions identified a distinct seasonal pattern in hospital admissions for those with mania. We found no secular trend. This could indicate that the climate change is not impacting on seasonal patterns, that there is no link between the proposed variables or that change is currently not sufficiently distinctive.

Mortality and secular trend in the incidence of bipolar disorder

BACKGROUND

The world-wide interest in bipolar disorder is illustrated by an exponential increase in publications on the disorder registered in Pubmed since 1990. This inspired an investigation of the epidemiology of bipolar disorder.

METHODS

This was a register-based cohort study. All first-ever diagnoses of bipolar disorder (International Classification of Diseases-10: F31) were identified in the nationwide Danish Psychiatric Central Research Register between 1995 and 2012. Causes of death were obtained from The Danish Register of Causes of Death. Age- and gender standardized incidence rates, standardized mortality ratio (SMR) and Kaplan-Meier survival estimates were calculated.

RESULTS

We identified 15,334 incident cases of bipolar disorder. The incidence rate increased from 18.5/100,000 person-years (PY) in 1995 to 28.4/100,000 PY in 2012. The mean age at time of diagnosis decreased significantly from 54.5 years in 1995 to 42.4 years in 2012 (p<0.001). The mean time from first affective diagnosis to diagnosis of bipolar disorder was 7.9 years (SD 9.1). The SMR was 1.7 (95%-CI 1.2-2.1). Causes of death were mainly natural; 9% died from suicide.

LIMITATIONS

Only patients in psychiatric care were included. The outpatient registry opened in 1995. Patients treated solely in outpatient units are not recorded previously. Systematic studies validating all the clinical diagnoses of the registry do not exist.

CONCLUSIONS

The incidence of bipolar disorder has increased in the last 10 years. The SMR was significantly increased. Half of the patients were known to have another affective disorder. This should be considered in future decisions regarding the healthcare organization.

Validity of diagnoses and other clinical register data in patients with affective disorder

Studies validating the clinical diagnoses of affective disorder recorded in case registers against research diagnostic criteria do not exist. In the present study, a random sample of 100 patients was selected among 21,734 patients who were recorded in the Danish Psychiatric Central Register with a diagnosis of manic-depressive psychosis at their first admission to psychiatric ward in a period from January 1, 1971 to December 31, 1993. Case notes from alt over Denmark were reviewed for all 100 patients and diagnoses were made with the use of OPCRIT. Patients who were still alive were contacted and interviewed face to face or by telephone. In total, 95 out of the 100 patients received an ICD-10 diagnosis of affective disorder computed with OPCRIT and confirmed at the interviews. Other clinical characteristics such as the age at onset and the number of affective episodes estimated from the register corresponded well with information from the case notes and the interviews.

Risk factors in relation to an emergence of bipolar disorder: a systematic review

OBJECTIVE

There is a consensus that genetic factors are important in the causation of bipolar disorder (BPD); however, little is known about other risk factors in the aetiology of BPD. Our aim was to review the literature on such risk factors - risk factors other than family history of affective disorders - as predictors for the initial onset of BPD.

METHODS

We conducted a literature search using the MEDLINE, PsycINFO and EMBASE databases. We selected factors of interest including demographic factors, factors related to birth, personal, social and family backgrounds, and history of medical conditions. The relevant studies were extracted systematically according to a search protocol.

RESULTS

We identified approximately 100 studies that addressed the associations between antecedent environmental factors and a later risk for BPD. Suggestive findings have been provided regarding pregnancy and obstetric complications, winter-spring birth, stressful life events, traumatic brain injuries and multiple sclerosis. However, evidence is still inconclusive. Childbirth is likely to be a risk factor. The inconsistency across studies and methodological issues inherent in the study designs are also discussed.

CONCLUSION

Owing to a paucity of studies and methodological issues, risk factors of BPD other than family history of affective disorders have generally been neither confirmed nor excluded. We call for further research.

Impact of bipolar affective disorder on family and partners

BACKGROUND

Successful management of major mental illness in the community relies significantly on an informal or non-professional network of caregivers. The needs and experiences of such caregivers have been little studied with respect to major chronic mood disorders.

METHOD

A sample of caregivers (n=41) of RDC bipolar disorder was systematically interviewed to determine how this role affected them.

RESULTS

Caregivers reported significant difficulties in their relationships with the patient when s/he was unwell, with considerable impact on their own employment, finances, legal matters, co-parenting and other social relationships. Violence was a particular worry for partner/parent caregivers of both male and female patients when the patient was manic. The caregiver's own mental health appeared unaffected. Despite this, the caregivers appeared emotionally committed to the patients and showed considerable tolerance of problem behaviours, which they rank-ordered for difficulty. Among nonfamily partners, knowledge of the illness before cohabitation was poor.

LIMITATION

The sampling does not capture caregivers who have abandoned their role, such as spouses who have divorced the bipolar sufferer.

CONCLUSIONS

Management of this illness requires a partnership between mental health professionals and the informal caregivers and the authors suggest that each group needs to understand the difficulties encountered by the other. Although erosion of relationships is a well-known complication of bipolar disorder, findings indicate that treating clinicians can rely on caregivers committed to the welfare of the patient.

Clinical definitions of sensitisation in affective disorder: a case register study of prevalence and prediction

The observation of a progressive recurrence in affective disorder has been interpreted as a process of sensitisation. The clinical applicability of such a theoretical model was investigated using the Danish case register, which includes all hospital admissions with primary affective disorder in Denmark from 1971 to 1993. A total of 8,737 patients admitted to a psychiatric hospital at least twice constituted the study sample. Information on treatment intervention was not available. Measures describing the initial course of admission episodes were defined in three different ways: 1) a short period between initial episodes 2) decreasing intervals between initial episodes or 3) a combination of 1) and 2). Socio-demographic variables such as gender, age at onset and marital status differentiated between the three types of measures and the measures also demonstrated different effects in predicting the risk of further recurrence. In unipolar disorder, patients with a decreasing interval between episodes had the greatest risk of further recurrence, whereas for bipolar patients, a short period between episodes played a more important role than the sequence of episodes in itself.

The 100-year epidemiology of schizophrenia

Since Kraepelin delineated dementia praecox as a disease entity construct, epidemiological studies conducted since the beginning of the century have produced remarkably consistent estimates of its prevalence, incidence and lifetime risk across various populations and geographic areas. A similar pattern emerged from the WHO ten-country study on first-contact incidence of schizophrenia. The diagnostic concept of dementia praecox originally used by Kraepelin and that of schizophrenia employed in the WHO studies were found to overlap extensively, indicating continuity over time. However, the findings of a similar incidence of schizophrenia in diverse populations and across time periods are unusual for a multifactorial disease and are compatible with at least two alternative interpretations that have different implications for the search for genetic and environmental causes of the disorder.

An adoption study comparing the prevalence of psychiatric illness in women who have adoptive and natural children compared with women who have adoptive children only

The current study compares the current and lifetime prevalence of affective disorder in women who have adopted and have natural children (n = 110) with women who only have adopted children (n = 176). There was no difference in lifetime prevalence of psychiatric disorder between the two groups and a nonsignificant trend for women who had born children to have had a major depressive episode during their lifetime 48 (44%) cf 62 (35%). The increased prevalence of psychiatric illness in married women with children cannot be explained by the biological fact of bearing children. None of the social variables related to child-rearing which were examined influenced the lifetime prevalence of psychiatric disorder.

The social networks of bipolar affective disorder patients

The social interaction parameters of a carefully delineated group of bipolar patients were compared to those of a random New Zealand community sample. The bipolar subjects had significantly lower scores for perceived availability and adequacy of both intimate and diffuse social relationships. Their mean scores did not differ from those of the subgroup in the random community survey who were classified as showing psychiatric morbidity, most of whom were depressed. Social interaction scores were negatively correlated with the bipolar patients' age and duration of illness. Those bipolar subjects with a predominance of manic episodes had lower mean values for their social interaction indices than those with more depressions. The results may suggest that the longer the illness continues, the greater is the impoverishment of the sufferer's social interaction patterns. Overall, manic episodes appeared to have a more deleterious effect on social relationships than depressive episodes.

Age at puberty and mental illness. Towards a neurodevelopmental aetiology of Kraepelin's endogenous psychoses

The hypothesis of a neurodevelopmental aetiology of manic-depressive psychosis and schizophrenia is based on the relation between onset of puberty and the final regressive events in the central nervous system (elimination of 40% of neuronal synapses), and the discrepancy in body build in the two disorders which is similar to that between early- and late-maturing individuals. The marked rise in manic-depressive psychoses and decline in schizophrenia, particularly the non-paranoid categories, accompanying the decline in mean pubertal age by some four years during the past hundred years are taken as evidence that manic-depressive psychosis affects early maturers and schizophrenia particularly affects late maturers. Gender differences and social differentials accord with this theory. Redundancy of neuronal synapses characterises manic-depressive psychosis, and reduced density of synapses is a characteristic of schizophrenia, whereas 'normality', with optimal synaptic density, is in between.

Mental illness and cognition in relation to age at puberty: a hypothesis

Onset of puberty is usually considered to coincide with the last major step in brain development: the elimination of some 40% of neuronal synapses. Mean pubertal age has declined by some 4 years during the last 100 years. There is a relation between age at puberty and body build, and between body build and mental illness. The difference in body build between schizophrenia (S) and manic-depressive psychosis (MDP) is similar to that between late and early maturers. It is suggested that S affects late-maturing individuals and MDP very early maturers. The observed marked rise in MDP and decline in the most malignant forms of S (non-paranoid) are in agreement with MDP and S as neurodevelopmental disorders occurring at the extremes of maturation. Maturational irregularities are most likely to occur at the extremes, and it is suggested that abbreviation of the regressive process may have led to persistent redundancy of neuronal synapses in MDP and that prolongation of the process past the optimal has yielded an inadequate synaptic density in S. The lack of cerebral abnormality in the majority of MDP and the presence of only subtle structural deficits in S, are in agreement with this. The two disorders are probably as old as mankind, and early puberty is the necessary factor for the development of MDP and late puberty is the necessary factor for that of S. There is an inverse relation between spatial ability and rate of maturation, whereas verbal ability is unaffected by maturational rate. From a previous predominance in both sexes, spatial ability (Performance IQ scores) has been reduced to below verbal ability (Verbal IQ scores) in the female sex and in early maturing males.

Gender, marital status and treated affective disorders in South Verona: a case register study

Data from the South Verona Psychiatric Case Register were used to test hypotheses about the relationship between age, gender, marital status and the incidence of treated affective disorders. Analysis of the 5-year period 1983-1987 yielded overall rates of affective disorder per 10(5) of 57.7 for males and 78.4 for women. Incidence increased with age both for depressive neurosis and for affective psychosis. Married women had high rates compared with their single counterparts whereas the reverse was true for men. The very low values for incidence are likely to reflect the major role in the treatment of affective disorders carried out by Italian general practitioners, rather than a low population rate of these disorders.

Marital status and depression: a study of English national admission statistics

Data are presented from the English national statistics for first admissions with affective disorders during the years 1982-1985. Overall rates per 10(5) of the population aged over 15 years were 36.1 for men and 59.1 for women. The peak incidence for depressive neurosis was middle adulthood, that for affective psychosis much later. The widowed and divorced showed much higher rates than the single and married for all types of disorder. Marriage appeared less protective for women than for men. The age-incidence relationship among the divorced and widowed was exaggerated for depressive neurosis and reversed for psychosis. The results are interpreted in terms of a (possibly biological) releasing effect of age upon affective psychosis that could be overwhelmed by severely adverse social circumstances. The findings support the validity of the distinction between affective psychoses and depressive neurosis.

Gender and symptoms of depression and anxiety among Kikuyu secondary school students in Kenya

Numerous studies have confirmed that patterns of mental illness are influenced by sociocultural factors such as socioeconomic status and gender. This study describes the patterning of symptoms of depression and anxiety on a 20 item self-report questionnaire, the Health Opinion Survey, completed by 159 Kikuyu secondary school students in Kenya. Significant quantitative differences in the responses of males and females to seven of the questions were found, including females reporting more depression symptoms than males. These results are compared to an earlier study of 116 Kikuyu adults in which the differences between males and females were greater. This paper contributes to the literature on the relationship between gender and depression while adding to the sparse descriptive literature on symptoms of depression and anxiety in normal African populations.

Sex differences in minor psychiatric morbidity

This monograph is concerned with some epidemiological observations of minor psychiatric morbidity. Differences in rates of specific disorders have historically formed a crucial part of epidemiological enquiry. Sex differences in the prevalence of minor affective disorders have been demonstrated in studies of populations in treatment and in community populations, and have been variously ascribed to constitutional or environmental factors. A review of the literature exposes the methodological problems of measurement and study design, and the conflicting nature of the findings. Efforts have recently concentrated on establishing the social factors important in the aetiology of minor affective disorder without adequate exclusion of constitutional factors. The importance of life events, chronic social stress and inadequate social supports in the aetiology of minor affective disorder has been demonstrated, but the variance explained by such factors is small, reinforcing the view that constitutional factors of some kind are likely to be of importance. The evidence for a genetic contribution to minor affective disorder is tenuous, but there is circumstantial evidence that changes in gonadal hormones are linked to mood changes in women. Until further evidence is available this must remain a powerful possibility in the genesis of sex differences in minor affective disorder. This investigation used epidemiological methods to assess whether there is a sex difference in the constitutional vulnerability of the male and female phenotype to minor psychiatric morbidity. In order to minimize the effects of environment and of sex roles and stereotypes as far as possible, a sample of relatively homogeneous employed men and women (drawn from a population of executive officers in the Home Office) was studied. The data obtained from this population of men and women of similar age, education, occupation and social environment were compatible with the null hypothesis that there is no sex difference in the prevalence of minor psychiatric morbidity, or its outcome in such a homogeneous group. However, women did report significantly more somatic symptoms than men. The second hypothesis, that there is a substantial sex difference in the self-perception of illness, illness behaviour and sickness absence in individuals with minor psychiatric morbidity among a homogeneous group of men and women of similar age, education and occupation, and subject to similar levels of social stress and support, received only partial support from the findings of the study.(ABSTRACT TRUNCATED AT 400 WORDS)

Marriage and mental health

Evidence linking psychiatric impairment with divorced marital status and the presence of marital discord is reviewed. Various theoretical models to explain these relationships are considered. Divorced marital status and marital discord are related to psychiatric impairment and mental health service utilization. Available evidence suggests that part of the impairment in these populations is secondary to factors involved in the breakdown of marital relationships and not completely explainable by premarital hypotheses. This has implications for mental health administrators.

The epidemiology of depressive disorder

The concept of depression is reviewed. Depression is defined as a syndrome and thus involves particularly subjective decisions by the diagnostician. The conceptual difficulties which arise from this are outlined. The rate of risk is reviewed, using both studies of treated cases and community interview surveys. The study of treated rates tells more of the variables affecting the process of declaration than of depression. It is proposed that case-finding has the prerequisite of precise case-definition with a standardized instrument. Only then can comparability be reached. The effect sociodemographic variables on rates of risk is analysed: it is concluded that they do not account for much of the variance because they are at best gross measures. The role of life events is assessed and it is argued that only by the study of their possible interactions with other factors will an adequate causal explanation of depression be achieved. The usefulness of this as a validation of the concept of depression is emphasized. In this paper we shall firstly look at how concepts of depression affect the process of arriving at a diagnosis and secondly at policies of case finding. We are then in a position to survey critically the findings of epidemiology in the study of depression. Finally, we will review work which throws light on the social causation of depression with the emphasis on recent developments.

Psychiatric treatment in a delimited population-with particular reference to outpatients. A demographic study

The present investigation analyses the psychiatric service available to and utilized by a population in a geogrphically delimited area, namely the Randers area with a population of 108.928. During the period 1970-74, the average yearly rate of patients admitted to the three psychiatric institutions covering this area was per 1,000: 7.9 males and 9.1 females. During 1970-71, 1.2 males and 1.8 females per 1,000 were treated as outpatients in a psychiatric clinic affiliated to a psychiatric hospital, and a psychiatric outpatient clinic in a general hospital discharged 4.1 males and 7.7 females per 1,000. It seems probable that despite outpatient treatment the number of admissions increases slightly rather than decreases, and consequently, outpatient treatment cannot replace psychiatric admission.