Seasonality prevalence and incidence of depressive disorder in a general practice sample: identifying differences in timing by caseness

Seasonal variation of depressive symptoms in unipolar major depressive disorder

OBJECTIVES

Retrospective and cross-sectional studies of seasonal variation of depressive symptoms in unipolar major depression have yielded conflicting results. We examined seasonal variation of mood symptoms in a long-term prospective cohort - the Collaborative Depression Study (CDS).

METHODS

The sample included 298 CDS participants from five academic centers with a prospectively derived diagnosis of unipolar major depression who were followed for at least ten years of annual or semi-annual assessments. Generalized linear mixed models were utilized to investigate the presence of seasonal patterns. In a subset of 271 participants followed for at least 20 years, the stability of a winter depressive pattern was assessed across the first two decades of follow-up.

RESULTS

A small increase in proportion of time depressed was found in the months surrounding the winter solstice, although the greatest symptom burden was seen in December through April with a peak in March. The relative burden of winter depressive symptoms in the first decade demonstrated no relationship to that of the second decade. The onset of new episodes was highest October through January, peaking in January.

CONCLUSIONS

There exists a small but statistically significant peak in depressive symptoms from the month of the winter solstice to the month of the spring equinox. However, the predominance of winter depressive symptoms did not appear stable over the long-term course of illness.

Self-attributed seasonality of mood and behavior: a report from the Netherlands study of depression and anxiety

BACKGROUND

Seasonal changes in mood and behavior are considered to be common in the general population and in patients with psychiatric disorders. However, in several studies this seasonality could not be demonstrated. The present study examined self-attributed seasonality of depressive symptoms among patients with a lifetime diagnosis of a depressive disorder (D), an anxiety disorder (A), a comorbid depressive and anxiety disorder (DA), and healthy controls (HC).

METHODS

The CIDI was used to establish diagnoses according to DSM-IV criteria in 2,168 participants of the Netherlands Study of Depression and Anxiety (NESDA). The Seasonal Pattern Assessment Questionnaire (SPAQ) was administered to assess variation in mood and behavior.

RESULTS

Of the 2,168 participants 53.5% reported seasonality of mood. Highest percentages of low mood were seen in the winter months. Although all groups showed this pattern of lowered mood during the winter months, D, A, and DA were significantly (P < .001) more likely to experience seasonality is this respect. This was also shown for seasonal changes in energy, social activities, sleeping, eating, weight and for the Global Seasonality Score. A limitation of this study was the cross-sectional design.

CONCLUSIONS

Seasonal variation in mood and behavior was demonstrated for both participants with a lifetime diagnosis of depression and/or anxiety disorder and for healthy controls, but patients with anxiety and/or depression were more likely to experience this seasonal variation. Clinicians should take into account that the time of the year could influence the feelings of well- and ill-being of their patients.

Seasonality in depressive and anxiety symptoms among primary care patients and in patients with depressive and anxiety disorders; results from the Netherlands Study of Depression and Anxiety

BACKGROUND

Little is known about seasonality of specific depressive symptoms and anxiety symptoms in different patient populations. This study aims to assess seasonal variation of depressive and anxiety symptoms in a primary care population and across participants who were classified in diagnostic groups 1) healthy controls 2) patients with a major depressive disorder, 3) patients with any anxiety disorder and 4) patients with a major depression and any anxiety disorder.

METHODS

Data were used from the Netherlands Study of Depression and Anxiety (NESDA). First, in 5549 patients from the NESDA primary care recruitment population the Kessler-10 screening questionnaire was used and data were analyzed across season in a multilevel linear model. Second, in 1090 subjects classified into four groups according to psychiatric status according to the Composite International Diagnostic Interview, overall depressive symptoms and atypical versus melancholic features were assessed with the Inventory of Depressive Symptoms. Anxiety and fear were assessed with the Beck Anxiety Inventory and the Fear questionnaire. Symptom levels across season were analyzed in a linear regression model.

RESULTS

In the primary care population the severity of depressive and anxiety symptoms did not show a seasonal pattern. In the diagnostic groups healthy controls and patients with any anxiety disorder, but not patients with a major depressive disorder, showed a small rise in depressive symptoms in winter. Atypical and melancholic symptoms were both elevated in winter. No seasonal pattern for anxiety symptoms was found. There was a small gender related seasonal effect for fear symptoms.

CONCLUSIONS

Seasonal differences in severity or type of depressive and anxiety symptoms, as measured with a general screening instrument and symptom questionnaires, were absent or small in effect size in a primary care population and in patient populations with a major depressive disorder and anxiety disorders.

Seasonal patterns of initiating antidepressant therapy in general practice in the Netherlands during 2002-2007

BACKGROUND

Studies on seasonality in antidepressant prescribing showed prescribing peaks during autumn and winter. Since then, new antidepressants have become available and indications have broadened, possibly contributing to a change in prescribing practices. This study investigates seasonal patterns of initiating antidepressant use in general practice during 2002-2007 in the Netherlands.

METHOD

Data were obtained from the Netherlands Information Network of General Practice. The study population was composed of adult patients initiating antidepressant use from 21 December 2001 to 20 December 2007, with no antidepressant use during at least two years prior to initiation. Seasonal distribution of initiating antidepressant use was investigated for the four seasons. The difference in frequency of initiating use between the seasons, normalized for general practice contacts, was tested using Chi-square testing.

RESULTS

The majority of the study population (N=16,289) was female (64.0%) with a mean age (standard deviation (SD)) of 50.5 (18.0) years. Significant seasonal variation (p<0.01) was found in initiation of antidepressant use, with about 5-35% more patients initiating use during winter than summer. Significant (p<0.01) seasonality of initiating antidepressant use was seen in all patient groups, except within age groups 18-30 years and >60 years.

LIMITATIONS

Our study investigated only general practitioner prescribing thus additional prescriptions from psychiatrists are missed.

CONCLUSIONS

The seasonal influence on initiation of antidepressant drug use has not changed with the introduction of the newer antidepressants and is in line with seasonality of depression onset, with most patients initiating use during the winter and fewest during the summer.

Observational studies of depression in primary care: what do we know?

BACKGROUND

We undertook a systematic review of observational studies of depression in primary care to determine 1) the nature and scope of the published studies 2) the methodological quality of the studies; 3) the identified recovery and risk factors for persistent depression and 3) the treatment and health service use patterns among patients.

METHODS

Searches were conducted in MEDLINE, CINAHL and PsycINFO using combinations of topic and keywords, and Medical Subject Headings in MEDLINE, Headings in CINAHL and descriptors in PsycINFO. Searches were limited to adult populations and articles published in English during 1985-2006.

RESULTS

40 articles from 17 observational cohort studies were identified, most were undertaken in the US or Europe. Studies varied widely in aims and methods making it difficult to meaningfully compare the results. Methodological limitations were common including: selection bias of patients and physicians; small sample sizes (range 35-108 patients at baseline and 20-59 patients at follow-up); and short follow-up times limiting the extent to which these studies can be used to inform our understanding of recovery and relapse among primary care patients with depression. Risk factors for the persistence of depression identified in this review were: severity and chronicity of the depressive episode, the presence of suicidal thoughts, antidepressant use, poorer self-reported quality of life, lower self-reported social support, experiencing key life events, lower education level and unemployment.

CONCLUSION

Despite the growing interest in depression being managed as a chronic illness, this review identified only 17 observational studies of depression in primary care, most of which have included small sample sizes and been relatively short-term. Future research should be large enough to investigate risk factors for chronicity and relapse, and should be conducted over a longer time frame.

Distinct seasonality of depressive episodes differentiates unipolar depressive patients with and without depressive mixed states

BACKGROUND

The bipolar nature of unipolar depression with depressive mixed states (DMX) needs further validation studies. The seasonality of depressive episodes is indicated to be different between unipolar and bipolar depressions. We therefore explored the seasonal pattern of depressive episodes in unipolar depressive patients with DMX.

METHODS

The subjects were 958 consecutive depressive inpatients for a 6-year period. For defining DMX, previously validated operational criteria were used (2 or more of 8 manic or mania-related symptoms: flight of idea, logorrhea, aggression, excessive social contact, increased drive, irritability, racing thoughts, and distractibility). Onsets of the index depressive episodes during each of the 12 calendar months were summed up over the 6-year for bipolar depressive patients (N = 95), and unipolar depressive patients with (N = 77) and without DMX (N = 786) separately. An appropriate statistic was used for testing seasonality.

RESULTS

A significant seasonal variation with a large peak in spring was recognized in unipolar depression without DMX, while both bipolar depression and unipolar depression with DMX had a significant fall peak. The monthly distribution of depressive episodes was significantly different between unipolar depression without DMX and other 2 diagnostic categories. Similar results were obtained in separate analyses for each gender.

LIMITATIONS

Further replication study using an epidemiological or outpatient sample is needed. Bipolar I and II patients were combined due to a small number of bipolar II patients in this sample.

CONCLUSION

Unipolar depression with DMX has a seasonal pattern similar to bipolar depression. The finding provides further evidence of the bipolar nature of unipolar depression with DMX.

Estimating depression prevalence from the Beck Depression Inventory: is season of administration a moderator?

The existence of winter seasonal affective disorder (SAD) and its milder population variants implies that depression estimates in a given population may tend to be higher in winter than at other times of the year. The aim of this study was therefore to test whether depression prevalence estimates based on the Beck Depression Inventory (BDI) are systematically moderated by season of administration. Existing information from the screening phase of a multicentre investigation of depression prevalence provided the data for the study. Repeated cross-sectional BDI data from samples in the United Kingdom (n=1299), Finland (n=1352), Norway (n=2711) and Spain (n=1246) were analysed for month- and season-of-administration effects. Whether data were measured continuously or as a dichotomous variable (BDI cutoff >/=13), there was no evidence of a systematic seasonal pattern in depression estimates across the four sites. No seasonal effects reached statistical significance at any single site, and trends in the association between winter and elevated BDI scores were positive in two sites (UK and Norway) and negative in two (Finland and Spain). Although limited by a post hoc analysis of existing data, this study provides the strongest evidence to date that season of administration is not a moderator of depression prevalence as estimated by the BDI.

Failure to replicate the effects of gender and season on the length of hospitalisation in unipolar depressives

BACKGROUND

Kecskés et al. [J. Affect. Dis. 73 (2003) 279] reported a possible effect of season and gender on the length of hospital stay among inpatients with a unipolar depression.

METHODS

The effects of season and gender upon the length of stay and clinical outcomes among 1283 inpatient admissions with unipolar depression diagnosed according to ICD-10 were examined.

RESULTS

Males had shorter length of stay but no better outcomes. There was no evidence of shorter lengths of stay for either gender in summer.

CONCLUSIONS

The present study failed to replicate the effect of season and gender on the length of stay in hospital among inpatients with unipolar major depression.

LIMITATIONS

The clinical outcomes were based upon a single item from the Health of the Nation Outcome Scales (HoNOS).

Factorial validity of the center for epidemiologic studies-depression (CES-D) scale in military peacekeepers

Despite widespread use of the Center for Epidemiologic Studies Depression Scale [CES-D], there are no investigations that examine its factor structure in a military sample. Separate confirmatory factor analyses were performed on responses to the CES-D obtained from 102 female and 102 male Canadian military peacekeepers in order to compare the fit of a four-factor intercorrelated (lower-order) model to a four-factor hierarchical (higher-order) model. The intercorrelated and hierarchical models fit the data well for both women and men, with hierarchical models fitting the data slightly better for women than men. These findings suggest that, for military women and men, the CES-D can be used to measure a set of distinct but interrelated depressive symptoms as well as a global construct of depression. Implications and future directions are discussed.

Identifying depression in primary care: a literature synthesis of case-finding instruments

We evaluated the usefulness of case-finding instruments for identifying patients with major depression or dysthymia in primary care settings using English language literature from Medline, a specialized trials registry and bibliographies of selected papers. Studies were done in primary care settings with unselected patients and compared case-finding instruments with accepted diagnostic criterion standards for major depression were selected. A total of 16 case-finding instruments were assessed in 38 studies. More than 32,000 patients received screening with a case-finding instrument; approximately 12,900 of these received criterion standard assessment. Case-finding instruments ranged in length from 1 to 30 questions. Average administration times ranged from less than 2 min to 6 min. Median sensitivity for major depression was 85% (range 50% to 97%); median specificity was 74% (range 51% to 98%). No significant differences between instruments were found. However for individual instruments, estimates of sensitivity and specificity varied significantly between studies. For the combined diagnoses of major depression or dysthymia, overall sensitivity was 79% (CI, 74% to 83%) and overall specificity 75% (CI, 70% to 81%). Stratified analyses showed no significant effects on overall instrument performance for study methodology, criterion standard choice, or patient characteristics. We found that multiple instruments with reasonable operating characteristics are available to help primary care clinicians identify patients with major depression. Because operating characteristics of these instruments are similar, selection of a particular instrument should depend on issues such as feasibility, administration and scoring times, and the instruments' ability to serve additional purposes, such as monitoring severity or response to therapy.

Use of health care services in seasonal affective disorder

BACKGROUND

Little is known about the presentation and management of seasonal affective disorder (SAD) in primary care.

AIMS

To determine the use of health care services by people suffering from SAD.

METHOD

Following a screening of patients consulting in primary care, 123 were identified as suffering from SAD. Each was age- and gender-matched with two primary care consulters with minimal seasonal morbidity, yielding 246 non-seasonal controls. From primary care records, health care usage over a 5-year period was established.

RESULTS

Patients with SAD consulted in primary care significantly more often than controls and presented with a wider variety of symptoms. They received more prescriptions, underwent more investigations and had more referrals to secondary care.

CONCLUSIONS

Patients with SAD are heavy users of health care services. This may reflect the condition itself, its comorbidity or factors related to the personality or help-seeking behaviour of sufferers.

Seasonal and nonseasonal depression: how do they differ? Symptom profile, clinical and family history in a general population sample

BACKGROUND

A small number of studies have previously compared the symptom profiles and clinical and family history patterns of patients with seasonal and nonseasonal depression. However, previous research has tended to be conducted in secondary and tertiary care populations. Little comparative data is available for seasonal and nonseasonal depression in general population samples.

METHODS

Patients aged 18-64 registered on a primary care database in North Wales were screened via post for the presence of SAD via the Seasonal Patterns Assessment Questionnaire (SPAQ) and depression via the Beck Depression Inventory (BDI). Interview-confirmed cases of SAD (n=25) and major depression (n=43) were compared in terms of symptom profile, clinical history and family history of psychiatric disorder.

RESULTS

Seasonal depression was found to be associated with lower occupational and cognitive impairment and psychiatric intervention than nonseasonal depression. The symptoms of hopelessness and weight loss were particularly predictive for nonseasonal depression.

LIMITATIONS

The study was conducted at only one geography.

CLINICAL RELEVANCE

Seasonal depression's discrete symptom profile may be used to distinguish cases of seasonal and nonseasonal depression in primary care patients.

CONCLUSIONS

SAD appears to be a relatively mild variant of depression, but this finding should not detract from the need for improved identification and treatment of SAD in primary care populations.

Bright light improves vitality and alleviates distress in healthy people

BACKGROUND

The relative shortage of light during the decreasing photoperiod may compromise well-being. Earlier studies suggest that bright-light exposure may be of help to alleviate winter-bound symptoms.

METHODS

We carried out a field study with exposure to bright light on office employees during winter.

RESULTS

Repeated bright-light exposure improved vitality and reduced depressive symptoms. The benefit was observed not only in healthy subjects with season-dependent symptoms but also in those not having the seasonal variation.

CONCLUSIONS

Bright-light exposure during winter appears to be effective at improving the health-related quality of life and alleviating distress in healthy subjects.

CLINICAL IMPLICATIONS

Administration of bright light is a useful option to improve vitality and mood among subjects working indoors in wintertime. LIMITATIONS OF STUDY: Our field setting used self-reports, not interviews, for the assessment of outcome.

Seasonal affective disorder

Seasonal affective disorder (SAD) is a form of recurrent depressive or bipolar disorder, with episodes that vary in severity. Seasonal patterns of depressive episodes are common, but SAD seems to be less common than such patterns suggest. SAD was at first believed to be related to abnormal melatonin metabolism, but later findings did not support this hypothesis. Studies of brain serotonin function support the hypothesis of disturbed activity. The short-allele polymorphism for serotonin transporter is more common in patients with SAD than in healthy people. Atypical depressive symptoms commonly precede impaired functioning, and somatic symptoms are frequently the presenting complaint at visits to family physicians. The best treatment regimens include 2500 Ix of artificial light exposure in the morning. When patients seem to have no response or to prefer another treatment, antidepressants should be considered.