Seasonal patterns of sickness absence due to diagnosed mental disorders: a nationwide 12-year register linkage study.

AIMS: Although seasonality has been documented for mental disorders, it is unknown whether similar patterns can be observed in employee sickness absence from work due to a wide range of mental disorders with different severity level, and to what extent the rate of change in light exposure plays a role. To address these limitations, we used daily based sickness absence records to examine seasonal patterns in employee sickness absence due to mental disorders. METHODS: We used nationwide diagnosis-specific psychiatric sickness absence claims data from 2006 to 2017 for adult individuals aged 16-67 (n = 636,543 sickness absence episodes) in Finland, a high-latitude country with a profound variation in daylength. The smoothed time-series of the ratio of observed and expected (O/E) daily counts of episodes were estimated, adjusted for variation in all-cause sickness absence rates during the year. RESULTS: Unipolar depressive disorders peaked in October-November and dipped in July, with similar associations in all forms of depression. Also, anxiety and non-organic sleep disorders peaked in October-November. Anxiety disorders dipped in January-February and in July-August, while non-organic sleep disorders dipped in April-August. Manic episodes reached a peak from March to July and dipped in September-November and in January-February. Seasonality was not dependent on the severity of the depressive disorder. CONCLUSIONS: These results suggest a seasonal variation in sickness absence due to common mental disorders and bipolar disorder, with high peaks in depressive, anxiety and sleep disorders towards the end of the year and a peak in manic episodes starting in spring. Rapid changes in light exposure may contribute to sickness absence due to bipolar disorder. The findings can help clinicians and workplaces prepare for seasonal variations in healthcare needs.

Hormonal contraception and mental health: results of a population-based study.

BACKGROUND: The effects of oral contraceptives (OCs) on mental health are not clear, and no study has been focused on the effects of the levonorgestrel-releasing intrauterine system (LNG-IUS) on mental health. The aim of this study was to analyse the association between the use of OCs and the LNG-IUS and psychological well-being and psychopathology. METHODS: The associations between the current use of OCs and the LNG-IUS, and their duration versus mood symptoms [Beck Depression Inventory (BDI)], psychological well-being [(General Health Questionnaire-12 (GHQ-12)] and recent psychiatric diagnoses [(Composite International Diagnostic Interview (CIDI)] were examined among women who participated in the Finnish-population-based Health 2000 study. Analyses were performed on the 30- to 54-year-old sample (n = 2310); some of the analyses were extended to include the younger age group (18- to 54-year-old sample; n = 3223). RESULTS: Overall, hormonal contraception was well tolerated with few significant effects on psychological well-being. The length of OC use was inversely associated with some BDI items ('dissatisfaction, irritability, lost interest in people, earlier waking and lost interest in sex'), and directly associated with 'worries about one's health' (BDI) and with a current diagnosis of 'alcohol dependence' (CIDI). The current use of the LNG-IUS was inversely associated with 'earlier waking' (BDI) and with 'impaired concentration' (GHQ), while the length of LNG-IUS use was inversely associated with 'strain' (GHQ). CONCLUSIONS: The influence of hormonal birth control on mental health is modest and mainly favourable. The length of current OC use seems to have some beneficial effects on mood although the longer the duration of use, the greater the association with a diagnosis of alcohol dependence. Knowledge of the use of hormonal contraception might be of value when assessing psychopathology in women. The cross-sectional design, with partly retrospective data collection, precludes any causal conclusions.

Work-related accidents and daylight saving time in Finland.

BACKGROUND: Recent research has indicated that transitions into and out of daylight saving time (DST) unbalance the physiological circadian rhythm and may lead to sleep disturbance. Sleep deprivation may have negative effects on motivation, attention and alertness and thus it is possible that transitions into and out of DST may increase accident rates. AIMS: To explore the impact of DST transitions on the number of occupational accidents in Finland. METHODS: For the study, we analysed all occupational accidents that happened in Finland 1 week before and 1 week after DST transitions during the years 2002-06. RESULTS: Transitions into and out of DST did not significantly increase the number of occupational accidents. CONCLUSIONS: It seems that sleep deprivation after DST transition is not harmful enough to impact on occupational accident rates.

DISC1 association, heterogeneity and interplay in schizophrenia and bipolar disorder.

Disrupted in schizophrenia 1 (DISC1) has been associated with risk of schizophrenia, schizoaffective disorder, bipolar disorder, major depression, autism and Asperger syndrome, but apart from in the original translocation family, true causal variants have yet to be confirmed. Here we report a harmonized association study for DISC1 in European cohorts of schizophrenia and bipolar disorder. We identify regions of significant association, demonstrate allele frequency heterogeneity and provide preliminary evidence for modifying interplay between variants. Whereas no associations survived permutation analysis in the combined data set, significant corrected associations were observed for bipolar disorder at rs1538979 in the Finnish cohorts (uncorrected P=0.00020; corrected P=0.016; odds ratio=2.73+/-95% confidence interval (CI) 1.42-5.27) and at rs821577 in the London cohort (uncorrected P=0.00070; corrected P=0.040; odds ratio=1.64+/-95% CI 1.23-2.19). The rs821577 single nucleotide polymorphism (SNP) showed evidence for increased risk within the combined European cohorts (odds ratio=1.27+/-95% CI 1.07-1.51), even though significant corrected association was not detected (uncorrected P=0.0058; corrected P=0.28). After conditioning the European data set on the two risk alleles, reanalysis revealed a third significant SNP association (uncorrected P=0.00050; corrected P=0.025). This SNP showed evidence for interplay, either increasing or decreasing risk, dependent upon the presence or absence of rs1538979 or rs821577. These findings provide further support for the role of DISC1 in psychiatric illness and demonstrate the presence of locus heterogeneity, with the effect that clinically relevant genetic variants may go undetected by standard analysis of combined cohorts.

Replication of linkage on chromosome 7q22 and association of the regional Reelin gene with working memory in schizophrenia families.

Schizophrenia is a common and complex mental disorder. Hereditary factors are important for its etiology, but despite linkage signals reported to several chromosomal regions in different populations, final identification of predisposing genes has remained a challenge. Utilizing a large family-based schizophrenia study sample from Finland, we have identified several linked loci: 1q32.2-q42, 2q, 4q31, 5q and 7q22. In this study, an independent sample of 352 nuclear schizophrenia families (n=1626) allowed replication of linkage on 7q21-32. In a sample of 245 nuclear families (n=1074) originating from the same geographical region as the families revealing the linkage, SNP and microsatellite association analyses of the four regional candidate genes, GRM3, RELN, SEMA3A and VGF, revealed no significant association to the clinical diagnosis of schizophrenia. Instead, quantifiable trait component analyses with neuropsychological endophenotypes available from 186 nuclear families (n=861) of the sample showed significant association to RELN variants for traits related to verbal (P=0.000003) and visual working memory (P=0.002), memory (P=0.002) and executive functioning (P=0.002). Trait-associated allele-positive subjects scored lower in the tests measuring working memory (P=0.0004-0.0000000004), memory (P=0.02-0.0001) and executive functioning (P=0.001). Our findings suggest that allelic variants of RELN contribute to the endophenotypes of schizophrenia.

Differences in clinical and cognitive variables in seasonal affective disorder compared to depressive-related disorders: Evidence from a population-based study in Finland.

BACKGROUND: Seasonal affective disorder (SAD) is a type of depression with seasonal pattern. Although it involves some idiosyncratic symptoms, it can overlap with other depressive disorders such as major depressive disorder (MDD) or dysthymia. We aimed to characterize the differences in specific cognitive and clinical symptoms between SAD and depressive-related disorders. METHODS: In total, 4554 Finnish subjects from the population-based Health 2011 Survey were interviewed with the Munich version of Composite International Diagnostic Interview (M-CIDI) and filled in the Seasonal Pattern Assessment Questionnaire (SPAQ). From this sample for our analysis, we included those participants who fulfilled the criteria for SAD (n=171), MDD (n=153) or dysthymia (n=84) and their 816 psychologically healthy controls matched by age and gender. In addition to M-CIDI and SPAQ, the Beck Depression Inventory, the General Health Questionnaire, an abbreviated version of the Mini-Mental State Examination, the category verbal fluency test, and the CERAD 10-word list were used. RESULTS: Subjects with dysthymia showed major deficits in both clinical and cognitive domains compared to MDD, SAD and healthy controls. Although clinical comorbidity was mild in SAD, these participants showed similar cognitive deficits to dysthymic subjects and greater impairments than MDD. CONCLUSIONS: SAD subjects show a differential clinical and cognitive profile compared to other depressive-related disorders. Although less severe clinical symptoms are found in these individuals, some cognitive impairment already appears in subjects with SAD recruited from a population-based study.

The association of air pollution and depressed mood in 70,928 individuals from four European cohorts.

BACKGROUND: Exposure to ambient air pollution may be associated with impaired mental health, including depression. However, evidence originates mainly from animal studies and epidemiological studies in specific subgroups. We investigated the association between air pollution and depressed mood in four European general population cohorts. METHODS: Data were obtained from LifeLines (the Netherlands), KORA (Germany), HUNT (Norway), and FINRISK (Finland). Residential exposure to particles (PM2.5, PM2.5absorbance, PM10) and nitrogen dioxide (NO2) was estimated using land use regression (LUR) models developed for the European Study of Cohorts for Air Pollution Effects (ESCAPE) and using European wide LUR models. Depressed mood was assessed with interviews and questionnaires. Logistic regression analyses were used to investigate the cohort specific associations between air pollution and depressed mood. RESULTS: A total of 70,928 participants were included in our analyses. Depressed mood ranged from 1.6% (KORA) to 11.3% (FINRISK). Cohort specific associations of the air pollutants and depressed mood showed heterogeneous results. For example, positive associations were found for NO2 in LifeLines (odds ratio [OR]=1.34; 95% CI: 1.17, 1.53 per 10 µg/m(3) increase in NO2), whereas negative associations were found in HUNT (OR=0.79; 95% CI: 0.66, 0.94 per 10 µg/m(3) increase in NO2). CONCLUSIONS: Our analyses of four European general population cohorts found no consistent evidence for an association between ambient air pollution and depressed mood.

Suppression of melatonin secretion by bright light in seasonal affective disorder.

Eleven patients with winter seasonal affective disorder and 10 healthy controls were exposed to light of 3300 lux for 5 min and for 1 hour respectively on consecutive evenings at 22:00 hours during winter and summer. In the winter, the measurements were undertaken both before and after the treatment with bright light for 2 weeks. In the summer, there was no treatment. Melatonin concentration in saliva and subjective sleepiness were measured at 22:00 and 23:00 hours on each test. There was no significant difference in the suppression of melatonin in response to the light tests between the patients and the controls. Exposure to light reduced the level of subjective sleepiness more among the patients compared to the control subjects. This reduction was not associated with the change in melatonin secretion nor the improvement in depressive symptoms.

Effects of bright light on sleepiness, melatonin, and 25-hydroxyvitamin D(3) in winter seasonal affective disorder.

Sixteen patients with winter seasonal affective disorder and 13 healthy controls were exposed to 3300 lx of cool-white fluorescent light for either 1 hour or 15 min in the morning for 2 weeks during the winter. Subjective sleepiness, melatonin concentration in saliva, and serum 25-hydroxyvitamin D(3) concentration were measured before and after the 2-week trial as well as the following summer when the patients were well. There were no significant differences in the baseline values between the patients and healthy subjects. No significant differences in the outcome measures were observed in the patients or the controls in the two groups of each after the trial. The exposure to bright light resulted in a significant decrease in subjective sleepiness early in the evening in the patients but not in the control subjects. The reduction of depressive symptoms was associated with the decrease in subjective sleepiness but not with the changes in the melatonin or vitamin D concentrations.

Patients excluded from an antidepressant efficacy trial.

BACKGROUND: The impact of exclusion criteria on antidepressant trials is rarely investigated and poorly understood. We describe specific reasons for exclusion from a double-blind comparative trial and analyze the selection procedure and its impact on treatment outcome. METHOD: A 6-week randomized double-blind trial for depressive disorders recruited patients through outpatient psychiatric services, private offices, and health care centers. Of the 612 consecutive patients interviewed for a diagnosis according to DSM-III-R, 209 (34%) finally entered the trial. RESULTS: 86% of the included patients had no comorbid psychiatric disorder, whereas a third of those excluded had at least one (p < .00001). Patients were excluded for having chronic alcohol or drug misuse (17%), receiving antidepressant drugs (15%), or having physical problems precluding their ability to take either of the drugs studied (14%). Some patients could not be included because of a referral to other modes of treatment (19%) or organizational difficulties (16%). The excluded patients less often suffered from major depressive disorder than those who were included in the trial. In particular, patients excluded because of suicidal thoughts or intent more often had a history of previous major depressive episodes (p = .006) compared with the included patients. The most important sociodemographic factors related to exclusion from the trial were male sex and unmarried status. CONCLUSION: Patients with previous depressive episodes or comorbid disorders were more likely to be excluded from the antidepressant efficacy trial. Data on the efficacy of antidepressant drugs on this patient population are still only infrequently obtained.

Effects of morning light treatment on subjective sleepiness and mood in winter depression.

The effects of morning light treatment on mood, subjective sleepiness and body temperature were investigated with 13 outpatients with winter depression and 13 healthy controls. Bright light for 1 h daily for 2 weeks resulted in a significant reduction in depression ratings and evening subjective sleepiness in the patients compared with the healthy controls. Even a short 15-min exposure to light daily produced these changes.

Effects of morning light treatment on subjective sleepiness and mood in winter depression.

The effects of morning light treatment on mood, subjective sleepiness and body temperature were investigated with 13 outpatients with winter depression and 13 healthy controls. Bright light for 1 h daily for 2 weeks resulted in a significant reduction in depression ratings and evening subjective sleepiness in the patients compared with the healthy controls. Even a short 15-min exposure to light daily produced these changes.

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.

Moclobemide and fluoxetine in treatment of seasonal affective disorder.

Of a total of 581 consecutive depressed subjects attending psychiatric services of 6 centres in Finland, 183 patients were eligible and completed a 6-week randomised double-blind trial with either moclobemide or fluoxetine. Of these, 32 (17.5%) patients met the DSM-III-R criteria for mood disorder with a seasonal (winter) pattern and 19 patients (10.5%) met the original criteria for seasonal affective disorder (SAD). There were no significant difference in the antidepressive response to the treatment between the patients with SAD and other depressive disorder. The treatment of 6 weeks with either moclobemide (300-450 mg daily) or fluoxetine (20-40 mg daily) resulted in a full remission in 15 (52%) patients with SAD and in 44 (37%) patients with other depressive disorder. Altogether, 23 (79%) and 83 (70%) patients, respectively, got significant benefit from the treatment. The improvement in the health-related quality of life in terms of ability to work was significantly more extensive in the patients with SAD assigned to receive moclobemide compared with the other depressive patients allocated to the same medication. Subjects who in addition met the operational criteria for atypical depression were equally distributed into the SAD and other depressive patient groups.

Bright-light exposure combined with physical exercise elevates mood.

BACKGROUND: Physical exercise alleviates depressive symptoms, as does exposure to bright light, especially in those with seasonal variation. Our objective was to compare the effect of exercise alone or combined with morning bright light on mood and the health-related quality of life in healthy subjects. METHODS: Study subjects were working-age adults, randomized in two groups (n=80): exercise in bright light (group A), or exercise in normal indoor illumination (group B). Intervention lasted for 8 weeks and questionnaire data on mood and the health-related quality of life were collected at study entry, and at weeks 4 and 8. RESULTS: Physical exercise both in normal indoor illumination and in bright light was effective at alleviating depressive symptoms. The exercise was significantly more effective at alleviating so-called atypical depressive symptoms when combined with bright-light exposure. LIMITATIONS: There was no active placebo condition, but a comparative, randomized trial was executed. CONCLUSIONS: Physical exercise in bright light had a positive effect on mood and health-related quality of life in a sample of healthy, working-age people. Further research is needed to explore the mechanisms of the apparent additive effect of exercise and light.

Bright light as an inhibitor of adenosine transport.

The administration of bright light rapidly improves subjective alertness and is likely to have direct effects on the activity of neurons in the suprachiasmatic nucleus (SCN). Bright light may enhance wakefulness by interrupting the increase in extracellular adenosine concentration with brain metabolism during the day. Exposure to bright light is hypothesized to induce the inhibition of adenosine transport, promoting both subjective alertness and activation measured objectively, and to activate the cholinergic neurons of the reticular system and those using gamma-aminobutyric acid as a neurotransmitter in the SCN.

Melatonin-dependent infertility.

Melatonin may be a key factor in the regulation of seasonal variation in gonadal activity. The circadian disturbances related to reproduction are probably subsequent to the seasonal change. Moreover, melatonin might also be considered essential for both spermatogenesis and folliculogenesis. Exposure to bright light, suppressing the concentration of melatonin in circulation, is hypothesized to be useful in treatment of both male and female infertility in couples with abnormal melatonin metabolism.

A mechanism of action underlying the antidepressant effect of light.

In patients with winter seasonal affective disorder (SAD), delayed and reduced responses to corticotropin-releasing factor (CRF) have been observed. Bright light treatment has been shown to normalize these responses. In depressed patients, there is increased CRF activity in the evening during the normally quiescent period between 19.30 and 22.00 hours. In patients with winter SAD, the level of subjective sleepiness is increased in the evening between 20.00 and 21.00 hours. In the latter group of patients, the CRF activity may be increased in the evening and associated with the increased level of subjective sleepiness. This increased activation is suggested to be normalized by bright light treatment, acting primarily on neurons of the paraventricular nucleus of the hypothalamus.