Influence of ultraviolet A1 exposures on mood states: a randomized controlled study.

We investigated the effects of daily ultraviolet A1 (UV-A1, 340-400 nm) exposures on mood states (#R19055, approval on 21 October 2020). Based on our earlier findings of the influence of diurnal preference on mood, we investigated further whether diurnal preference plays a role in the influence of UV-A1 on mood states. Forty-one healthy participants aged 19-55 years were randomized to receive either UV-A1 (n = 21) or control (n = 20) exposures (violet light, 390-440 nm). The irradiations were administered on three consecutive mornings on the skin of the buttocks and middle back. Diurnal preference was assessed with the modified 6-item Morningness-Eveningness Questionnaire (mMEQ). Changes in mood were assessed with Total Mood Disturbance (TMD) score of the 40-item Profile of Mood States (POMS) before the first irradiation, immediately after each irradiation and one week after the last irradiation. Mood improved among those subjected to UV-A1 exposures compared with the controls (p = 0.031). Individuals with more pronounced morningness had mood improvement (p = 0.011), whereas those with more pronounced eveningness did not (p = 0.41). At follow-up of one week after the last irradiation the mood improvement had disappeared.

Moderate associations between the use of levonorgestrel-releasing intrauterine device and metabolomics profile.

CONTEXT: Use of levonorgestrel-releasing intrauterine device (LNG-IUD) has become common irrespective of age and parity. To date, only a few studies have examined its possible metabolic changes and large-scale biomarker profiles in detail and in a longitudinal design. OBJECTIVE: To apply the metabolomics technique to examine the metabolic profile associated with the use of LNG-IUD both in a cross-sectional and in a longitudinal design. DESIGN: The study consists of cross-sectional and longitudinal analyses of a population-based survey (Health 2000) and its 11-year follow-up (Health 2011). All participants aged 18-49 years with available information on hormonal contraceptive use and metabolomics data (n=1767) were included. Altogether 212 metabolic measures in LNG-IUD users (n=341) were compared to those in non-users of hormonal contraception (n=1426) via multivariable linear regression models. Participants with complete longitudinal information (n=240) were divided into continuers, stoppers, starters, and never-user groups, and 11-year changes in levels of each metabolite were compared. RESULTS: After adjustment for covariates, levels of 102 metabolites differed in LNG-IUD current users compared to non-users of hormonal contraception (median difference in biomarker concentration: -0.12 SD): lower levels of fatty acids concentrations and ratios, cholesterol, triglycerides and other lipids, as well as particle concentration, cholesterol, total lipids and phospholipids in lipoproteins. The 11-year metabolic changes did not differ in relation to changes in LNG-IUD use. CONCLUSIONS: The use of LNG-IUD was associated with several moderate metabolic changes, mostly suggestive of a reduced arterial cardiometabolic risk. Changes in LNG-IUD use were not related to long-term metabolic changes.

Narrow-band UVB radiation triggers diverse changes in the gene expression and induces the accumulation of M1 macrophages in human skin.

BACKGROUND: The underlying molecular mechanisms that determine the biological effects of UVB radiation exposure on human skin are still only partially comprehended. OBJECTIVES: Our goal is to examine the human skin transcriptome and related molecular mechanisms following a single exposure to UVB in the morning versus evening. METHODS: We exposed 20 volunteer females to four-fold standard erythema doses (SED4) of narrow-band UVB (309-313 nm) in the morning or evening and studied skin transcriptome 24 h after the exposure. We performed enrichment analyses of gene pathways, predicted changes in skin cell composition using cellular deconvolution, and correlated cell proportions with gene expression. RESULTS: In the skin transcriptome, UVB exposure yielded 1384 differentially expressed genes (DEGs) in the morning and 1295 DEGs in the evening, of which the most statistically significant DEGs enhanced proteasome and spliceosome pathways. Unexposed control samples showed difference by 321 DEGs in the morning vs evening, which was related to differences in genes associated with the circadian rhythm. After the UVB exposure, the fraction of proinflammatory M1 macrophages was significantly increased at both timepoints, and this increase was positively correlated with pathways on Myc targets and mTORC1 signaling. In the evening, the skin clinical erythema was more severe and had stronger positive correlation with the number of M1 macrophages than in the morning after UVB exposure. The fractions of myeloid and plasmacytoid dendritic cells and CD8 T cells were significantly decreased in the morning but not in the evening. CONCLUSIONS: NB-UVB-exposure causes changes in skin transcriptome, inhibiting cell division, and promoting proteasome activity and repair responses, both in the morning and in the evening. Inflammatory M1 macrophages may drive the UV-induced skin responses by exacerbating inflammation and erythema. These findings highlight how the same UVB exposure influences skin responses differently in morning versus evening and presents a possible explanation to the differences in gene expression in the skin after UVB irradiation at these two timepoints.

Does the duration of diabetes increase the risk of cancer? A nationwide population-based cohort of patients with new-onset diabetes and a matched reference cohort.

Diabetes mellitus and cancer are both common health issues, but the correlation between these two diseases remains unclear. We investigated the association of cumulative exposure of diabetes mellitus as an indication of hyperglycemia in terms of disease duration on multiple cancer types. We hypothesized that the risk of cancer would increase over time after the onset of diabetes. The study population consisted of a population-based cohort of 398,708 people and it was constructed from the Finnish CARING project. The Diabetes group consisted of 185,258 individuals, and the non-diabetic reference group comprised 187,921 individuals. Over 4.1 million person-years were accumulated, and the median follow-up time was 10.55 years. In the diabetes group, 25,899 cancer cases were observed compared with 23,900 cancers in the non-diabetic group. We did not find a clear relationship between the duration of diabetes mellitus and most cancer types examined. However, for cancers of the pancreas, prostate gland, bronchus, and lungs, a temporal relationship was found. Furthermore, even within the cancer types where the relationship was detected, it did not change over time. These findings indicate that diabetes does not independently increase the risk of cancer. Instead, the development of diabetes may be attributed to shared risk factors with cancer, such as obesity and/or insulin resistance accompanied by hyperinsulinemia. Thus, it is likely that the clock for increased cancer risk starts ticking already before onset of diabetes and hyperglycemia.

Work ability trends 2000-2020 and birth-cohort projections until 2040 in Finland.

Aims: To examine age-group and birth-cohort trends in perceived work ability in Finland in 2000-2020 and make projections of perceived work ability up to 2040 based on the observed birth-cohort development. Methods: Ten population-representative cross-sectional surveys conducted in Finland between 2000 and 2020 were used (overall N = 61,087, range 817-18,956). Self-reported estimates of current work ability in relation to the person's lifetime best on a scale from zero to ten (0-10) were classified into three groups: limited (0-5), intermediate (6-7), and good (8-10). Multiple imputation was used in projecting work ability. Results: Examining past trends by 5-year birth-cohorts born between 1961 and 1995 showed that work ability has declined steadily over time among older birth-cohorts, while in the two younger cohorts a stable development before 2017 and a steep decline between 2017 and 2020 was seen. Trends by 5-year age groups showed a declining trend of good work ability among 20-44-year-olds, a stable trend among 45-54-year-olds, and an improving trend among 55-year-olds and older was observed for the period 2000-2020. Among the under 55-year-olds the prevalence of good work ability ended up around 75% and at 68% among the 55-59-year-olds, 58% among the 60-69-year-olds and 49% among the 70-74-year-olds in 2020. Birth-cohort projections suggested a declining work ability in the future among all age groups included (30-74 years). By 2040, the prevalence of good work ability is projected to decline by 10 to 15 percentage points among 45-74-year-olds. Conclusions: The projections suggest declining work ability in the future. Efforts to counteract the decline in work ability are needed.

Stability of morningness/eveningness and changes in sleep and mental health during mid-adulthood.

Objective: A change toward Eveningness in circadian sleep-wake behavior is generally seen from childhood to adolescence, but less is known about circadian changes during adulthood. Circadian changes during mid-adulthood are of high interest, since Eveningness associates with a range of health-related problems, including psychological symptoms and mental disorders. In this study, we examined the circadian stability across 10 years, from 42 to 52 years of age, and how it is associated with sleep and mental health in a Finnish general population cohort follow-up-based (n = 976). Method: Circadian type was assessed at both ages with a widely used item for self-estimated Morningness/Eveningness from the original Horne-Östberg Morningness-Eveningness Questionnaire. Generalized estimating equations were used for analyzing how a change in Morningness/Eveningness was associated with sleep and mental health longitudinally. Results: Our findings indicate that the circadian type is a highly stable trait during mid-adulthood with mainly moderate changes occurring in 42.2% of adults and no circadian change among 57.8% of adults. Most changes occurred within the same circadian type (23.9%), second to changes between moderate circadian types (13.3%). Changes between the Definite Evening-types and Morning-types were very rare (0.5%). Stable Evening-types reported more insufficient sleep, discrepancy between sleep duration on workdays and free days, and depression as compared to stable Morning-types. Moderate changes toward Morningness, comprising mostly those within Morning-types, were associated with reduced distress and psychological symptoms. Conclusions: In conclusion, our findings show high stability of mid-adulthood circadian type. However, changes toward Morningness seem to be associated with improved mental health. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Associations of allostatic load with sociodemographic factors, depressive symptoms, lifestyle, and health characteristics in a large general population-based sample.

OBJECTIVE: We examined the associations between allostatic load (AL) and sociodemographic factors, depressive symptoms, lifestyle and health characteristics in a population-based sample of 4993 adults in Finland. METHODS: Thirteen biomarkers were used to construct AL. High AL was defined as scoring highly in ≥4 items. RESULTS: AL scores of 4 and above were exceeded in the age group of 45-54 years in men and 65-74 years in women. Age was the strongest predictor for belonging to the high AL score group. In addition, elevated depressive symptoms (BDI-6 ≥ 4), male sex, not engaging in physical exercise, high alcohol use and a low level of education were associated with an increased likelihood of belonging to the high AL group. CONCLUSION: The older the participants were, the greater their AL burden was. However, AL burden increased more steeply as a function of age in men. In addition to lifestyle interventions, effective prevention strategies for depression at the population level could have a major public health impact in reducing the accumulation of AL burden.

Daylight during winters and symptoms of depression and sleep problems: A within-individual analysis.

BACKGROUND: With climate change Northern areas of the globe are expected to have less daylight during winters due to less snow and more cloudiness. While wintertime has been linked to mental health problems, the role of wintertime daylight has been scarcely studied. We examined longitudinal associations for wintertime objective exposure to global radiation and self-reported daylight exposure with symptoms of depression and sleep problems. METHODS: Our analytical sample included 15,619 respondents from three Swedish Longitudinal Occupational Surveys of Health (2012, 2014 and 2016). Objective exposure was global radiation (MJ/m2, November-January and November-February). Subjective exposure was based on self-reported time spent outdoors in daylight (<1 h vs. ≥ 1 h, November-January). Symptoms of depression were evaluated using a six-item subscale of the (Hopkins) Symptom Checklist. Fixed-effects method with conditional logistic regression controlled for time-invariant participant characteristics by design and time-varying covariates were added into models. RESULTS: One unit increase in the four-month averaged global radiation was associated with lower odds of depressive symptoms (OR 0.69, 95 % CI 0.52-0.91). These findings were confirmed using four-month cumulative exposure (OR 0.91, 95 % CI 0.85-0.98). Individuals reporting ≥ 1 h exposure to daylight during winter months were less likely to report depressive symptoms (OR 0.72, 95 % CI 0.60-0.82) compared to time when their exposure was < 1 h. Higher three-month exposure to global radiation suggested a protective association for sleep problems. CONCLUSION: These findings suggest that higher exposure to daylight during winters may contribute to lower likelihood of depression symptoms.

Childhood Bullying as a Predictor of Suicidality in Young Adults in a Nationwide Population-Based Health Examination Study.

OBJECTIVE: Having been bullied at school in childhood links to suicidality. We aimed at verifying earlier findings and delivering diverse data from a representative population-based sample of young adults to characterize the impacts beyond childhood. METHOD: A random sample of adults, aged 18-28 years and representative of the general population living in Finland, participated in a nationwide health examination study. Adverse childhood experiences before the age of 16 years were analyzed for 779 participants in relation to lifetime suicidality (suicidal ideation, suicide attempts), current suicidal thoughts (HSCL-25), mental disorders (self-reports for lifetime, M-CIDI for DSM-IV during the past 12 months), current usage of mental health services, current usage of prescription medicines (ATC codes), current psychological distress (GHQ-12), and current work capacity and work ability. RESULTS: Having been bullied in childhood contributed to greater suicidality (p < 0.001), more frequent current usage of antipsychotics (p < 0.001) as well as antidepressants (p < 0.001), greater current psychological distress (p < 0.001), and poorer current work capacity (p < 0.001) as well as work ability (p < 0.001). Of the self-reported mental disorders on lifetime basis, psychosis had the strongest association (p = 0.03) with having been bullied, whereas the interview-based diagnosis of mental disorders during the past 12 months had no significant association. CONCLUSIONS: Having been bullied at school before the age of 16 years was independently associated not only with suicidality, but also with the self-report of psychosis as well as a range of indicators of poorer mental health at the age of 18-28 years.

Having been bullied at school contributed to suicidality in young adults.Having been bullied linked to current use of antipsychotics and antidepressants.Having been bullied associated with poor work capacity and poor work ability.

Impacts of temperature and solar radiation changes in northern Europe on key population health behaviors: a scoping review of reviews.

AIM: Climate change threatens health directly as well as indirectly through impacts on health-related behaviors. Physical activity, nutrition and sleep are key health-related behaviors for population health. We aimed at elucidating the impacts of climate change which emerge gradually on these three key health-related behaviors, particularly focusing on scenarios and projections relevant to people living in the northern Europe. METHODS: We conducted a systematic literature search in three different databases in January 2023 to identify English language review articles summarizing the effects of climate change on either physical activity, nutrition, sleep, or their combination. RESULTS: We identified 15 review articles on the topic. Data on climate change impacts on nutrition and sleep were sparse, and those on physical activity were heterogeneous. The climate in northern Europe will become warmer and sunnier in summer as well as warmer and darker in winter, which will probably increase the level of physical activity, but decrease the consumption of fruits and vegetables, as well as increase the occurrence of sleep disturbances in a population. CONCLUSIONS: The anticipated changes in physical activity, nutrition and sleep driven by climate change influence population health and call for grass-roots action plans for adaptation.

Targeted health promotion with guided nature walks or group exercise: a controlled trial in primary care.

Background: Contact with nature promotes wellbeing through diverse pathways, providing a potential way of supporting health especially in primary care, where patients commonly suffer from multimorbidity and poor general health. Social prescribing is a non-pharmaceutical approach for improving health as well as social inclusion. This field study explores and compares the effects of a nature-based and an exercise-based social prescribing scheme on mental wellbeing and sleep, in a primary care population. Methods: Primary care patients identified to benefit from a general improvement to their health were recruited by nurses, doctors, or social workers to this non-randomized, intention-to-treat, pilot field-study. Participants (n = 79) chose between the group interventions, either taking part in guided walks in nature, including immersion in a forest with high biodiversity, or participating in a versatile sports program. Mental wellbeing was assessed with the Warwick-Edinburgh Mental Well-Being Scale (WEMWBS), with additional questions evaluating self-rated health and sleep. Impact on mental wellbeing was explored in relation to perceived health. The amount and quality of sleep was measured with wrist-worn accelerometers. With a focus on everyday life impacts, the assessments took place before and after the 8-week intervention. All participants lived in Sipoo, Finland, an area with abundant accessible green space. Results: Participants (mean age 57 years, 79% female) rated their general and mental health lower than the general population. Participation in the Nature-group resulted in improved mental wellbeing (change in WEMWBS by 3.15, p = 0.008), with a positive change for feeling relaxed, being cheerful, having energy to spare, feeling able to deal well with problems, feeling good about oneself and feeling close to other people. The Sports-group was beneficial for those initially rating their health as good. Sleep duration improved in the Sports-group, while participants in the Nature-group reported better sleep quality. Following the interventions there was improvement in perceived health and ability to function in both groups, while perceived mental health improved only in the Nature-group. Conclusion: We attest that even in areas surrounded by greenery, active interventions can further improve health in a primary care population, and that nature-based interventions are beneficial for those in poor health. Clinical trial registration: ClinicalTrials.gov, Identifier NCT05893212.

Cynical hostility increases whereas sense of coherence decreases the odds for current suicidal thoughts: A cross-sectional study of the general adult population sample.

Background and Aims: Earlier, somatic diseases and mental disorders have been associated with cynical hostility as well as sense of coherence, but there is a gap of knowledge, whether they contribute to suicidality at population level. Methods: A random sample of adults, representative of the general population living in Finland, participated in a nationwide health examination study. For 4387 participants aged 18-97 years, we analyzed, after controlling for confounding factors, whether cynical hostility, as assessed with the 8-item Cook-Medley Hostility Scale, or sense of coherence, as assessed with the 13-item Sense of Coherence Scale, contributed to current suicidal thoughts during the past 7 days as scored on the 25-item Hopkins Symptom Checklist. Results: Suicidal thoughts (current thoughts of ending one's life) were associated significantly with cynical hostility (p < 0.001) as well as with sense of coherence (p < 0.001). Of the specific items of cynical hostility, the item "I am sure that most people do not have problems with lying for their own good" was associated most strongly with current suicidal thoughts (p < 0.001). Conclusion: Cynical hostility predicted current suicidal thoughts in a population-based sample of adults aged 18-97 years. Sense of coherence protected from current suicidal thoughts.

Severe or chronic disease in childhood predicts suicidality and links to anxiety in young adulthood.

PURPOSE: Suicide prevention needs measures, and further understanding of the role of adverse childhood experiences may elucidate the suicide process and ease the identification of suicide risk. MATERIALS AND METHODS: A random sample of adults, aged 18-28 years and representative of the general population living in Finland, participated in a nationwide health examination survey. Of them (n = 793) we analyzed whether severe or chronic disease in childhood before the age of 16 years contributed to suicidality (suicidal ideation and/or suicide attempts), and whether severe or chronic disease in childhood was associated with mental disorders, current psychological distress, current usage of prescription medicines, or current work capacity. RESULTS: Having severe or chronic disease in childhood contributed independently to suicidality, with the odds ratio of 5.41 (95% confidence interval of 2.98-9.82, p < .001), but the significance of this association was lost after controlling for mental disorders. Having severe or chronic disease during childhood, as compared not having such condition, was associated with having more frequently anxiety (p < .001), greater psychological distress (p < .001), more frequently usage of psychotropic medicines (p < .001), and poorer work capacity (p < .001). CONCLUSION: Having severe or chronic disease in childhood not only increased the odds for suicidality, but also associated with anxiety, current psychological distress, current usage of psychotropic medication, and current work capacity in young adulthood.

Hormonal contraception use and insomnia: A nested case-control study.

Evidence is limited concerning possible associations between the use of hormonal contraception and insomnia. We applied the nested case-control design on a nationwide sample of women, aged 15-49 years, derived from national health care registries to characterize the association between the use of hormonal contraception and the occurrence of insomnia. There were altogether 294,356 users and 294,356 non-users of hormonal contraception. 11,105 new cases of insomnia emerged among the 1,148,969 person-years of the follow-up period of two years. All the significant associations of hormonal contraception with insomnia emerged among the participants aged 34 years or younger, and if only the tertiary care data was concerned, among the those aged 15-19 years. The users of the fixed combination of drospirenone and ethinylestradiol as well as that of cyproterone and ethinylestradiol had significantly decreased odds for insomnia, whereas the users levonorgestrel-releasing intrauterine devise as well as those of vaginal ring with etonogestrel and ethinylestradiol had significantly increased odds for insomnia as compared with non-users. Our findings suggest that different products prescribed for hormonal contraception may be differentially associated with the occurrence of insomnia.

Potential links between brown adipose tissue, circadian dysregulation, and suicide risk.

Circadian desynchronizations are associated with psychiatric disorders as well as with higher suicidal risk. Brown adipose tissue (BAT) is important in the regulation of body temperature and contributes to the homeostasis of the metabolic, cardiovascular, skeletal muscle or central nervous system. BAT is under neuronal, hormonal and immune control and secrets batokines: i.e., autocrine, paracrine and endocrine active substances. Moreover, BAT is involved in circadian system. Light, ambient temperature as well as exogen substances interact with BAT. Thus, a dysregulation of BAT can indirectly worsen psychiatric conditions and the risk of suicide, as one of previously suggested explanations for the seasonality of suicide rate. Furthermore, overactivation of BAT is associated with lower body weight and lower level of blood lipids. Reduced body mass index (BMI) or decrease in BMI respectively, as well as lower triglyceride concentrations were found to correlate with higher risk of suicide, however the findings are inconclusive. Hyperactivation or dysregulation of BAT in relation to the circadian system as a possible common factor is discussed. Interestingly, substances with proven efficacy in reducing suicidal risk, like clozapine or lithium, interact with BAT. The effects of clozapine on fat tissue are stronger and might differ qualitatively from other antipsychotics; however, the significance remains unclear. We suggest that BAT is involved in the brain/environment homeostasis and deserves attention from a psychiatric point of view. Better understanding of circadian disruptions and its mechanisms can contribute to personalized diagnostic and therapy as well as better assessment of suicide risk.

Melatonin immunoreactivity of epidermal skin is higher in the evening than morning but does not account for erythema sensitivity.

The skin is a site of melatonin synthesis, and melatonin has a role in protecting against ultraviolet radiation-induced damage. Ultraviolet B (UVB) induced erythema seems to vary between morning and evening. We investigated whether epidermal melatonin immunoreactivities in the morning differed from those in the evening, and whether UVB-induced erythema was associated with these melatonin immunoreactivities in healthy volunteers. Erythema sensitivity of the skin was determined in the morning and in the evening by scoring the Minimal Erythema Dose and quantifying the erythema index (EI). We took biopsies from the non-UVB-exposed skin of healthy volunteers (n = 39) in the morning and in the evening to study melatonin immunoreactivity with immunohistochemistry (IHC). In the IHC staining, there was more melatonin immunoreactivity in the evening than in the morning (p < .001). Erythema was more pronounced in the evening than in the morning irradiated skin (p < .001). The graded amount of melatonin immunoreactivity in the samples was not associated with the EI. We discovered melatonin immunoreactivity of the non-irradiated skin to vary diurnally. However, endogenous skin melatonin does not seem to be the reason why NB-UVB induces more erythema in the evening than in the morning.

Being able to enjoy normal day to day activities separates suicidal ideation from attempted suicide in a nationwide population-based health examination study of adults aged 18 to 28 years.

PURPOSE: A higher total score on the General Health Questionnaire (GHQ-12) is associated with a higher likelihood of having suicidal ideation as well as having suicide attempt. The association of GHQ-12 with suicide attempts item by item has not been analyzed earlier. MATERIALS AND METHODS: In a population-based sample, aged 18 to 28 years, mental illness was assessed as self-reported during the interview. Participants were also asked to score on two specific questions concerning suicidal ideation as well as attempted suicide. The GHQ-12 total score and each of the 12 item scores of the GHQ-12 were analyzed with regression models to explain suicidality (n = 679). RESULTS: The total score of GHQ-12 differed by suicidality (Bonferroni-corrected p < 0.001). The item 6 (Felt that could not overcome difficulties) and the item 11 (Feeling oneself worthless) were associated with suicidal ideation (OR = 1.66, 95% CI = 1.12-2.47, p = 0.01 and OR = 1.58, 95% CI = 1.04-2.39, p = 0.03, respectively) as well as with suicide attempts (OR = 2.82, 95% CI = 1.54-5.16, p = 0.001 and OR = 3.10, 95% CI = 1.64-5.85, p < 0.001, respectively). The item 7 (Able to enjoy normal day to day activities) was associated with suicide attempts (OR = 0.28, 95% CI = 0.12-0.64, p = 0.003) and made the item-specific difference between those with suicidal ideation w/o suicide attempt (OR = 0.35, 95% CI = 0.14-0.89, p = 0.03). CONCLUSION: Being able to enjoy normal activities day to day made a difference between suicidal ideation and attempted suicide.

Long-term residential sunlight exposure associated with cognitive function among adults residing in Finland.

While sunlight may influence cognitive function through several pathways, associations of residential sunlight exposure with cognitive function are not well known. We evaluated associations of long-term residential sunlight exposure with cognitive function among a representative cohort of 1838 Finnish adults residing in Finland who underwent comprehensive cognitive assessment in midlife. We linked daily recordings of global solar radiation to study participants using residential information and calculated the average daily residential exposure to sunlight for four exposure time intervals: 2 months, 1 year, 2 years and 5 years prior to the date of the cognition assessment. Associations of the residential sunlight exposure with cognitive function were assessed using linear regression analyses adjusting for season, sex, age, and individual- and neighborhood-level socioeconomic characteristics. Greater average residential sunlight exposure over 2 and 5 years prior to the cognitive function assessment was associated with better global cognitive function (b = 0.13, 95% CI = 0.01, 0.25; b = 0.17, 95% CI = 0.05, 0.29, per 1 MJ/m2 difference in sunlight exposure), while no associations with global cognitive function were observed at shorter exposure time intervals. In domain-specific analyses, greater residential exposure to sunlight over 1, 2 and 5 years prior to the cognitive function assessment was associated with better performance on new learning and visual memory (b = 0.10, 95% CI = 0.00, 0.20; b = 0.16, 95% CI = 0.04, 0.28; b = 0.19, 95% CI = 0.08, 0.31) and sustained attention (b = 0.15, 95% CI = 0.05, 0.25; b = 0.18, 95% CI = 0.06, 0.30; b = 0.17, 95% CI = 0.05, 0.29), but worse performance on reaction time (b = - 0.12, 95% CI = - 0.22, - 0.02; b = -0.15, 95% CI = - 0.28, - 0.02; b = - 0.18, 95% CI = - 0.30, - 0.05). Residential sunlight exposure was not associated with executive function. These findings suggest long-term residential sunlight exposure may be an environmental factor influencing cognitive function among a cognitively healthy cohort residing in Northern Europe. Further studies in populations residing in different geographical locations are needed.

The metabolic regulator USF-1 is involved in the control of affective behaviour in mice.

Epidemiological studies indicate a bidirectional association between metabolic disturbances, including obesity and related pathological states, and mood disorders, most prominently major depression. However, the biological mechanisms mediating the comorbid relationship between the deranged metabolic and mood states remain incompletely understood. Here, we tested the hypothesis that the enhanced activation of brown fat tissue (BAT), known to beneficially regulate obesity and accompanying dysfunctional metabolic states, is also paralleled by an alteration of affective behaviour. We used upstream stimulatory factor 1 (USF-1) knock-out (KO) mice as a genetic model of constitutively activated BAT and positive cardiometabolic traits and found a reduction of depression-like and anxiety-like behaviours associated with USF-1 deficiency. Surgical removal of interscapular BAT did not impact the behavioural phenotype of USF-1 KO mice. Further, the absence of USF-1 did not lead to alterations of adult hippocampal neural progenitor cell proliferation, differentiation, or survival. RNA-seq analysis characterised the molecular signature of USF-1 deficiency in the hippocampus and revealed a significant increase in the expression of several members of the X-linked lymphocyte-regulated (xlr) genes, including xlr3b and xlr4b. Xlr genes are the mouse orthologues of the human FAM9 gene family and are implicated in the regulation of dendritic branching, dendritic spine number and morphology. The transcriptional changes were associated with morphological alterations in hippocampal neurons, manifested in reduced dendritic length and complexity in USF-1 KO mice. Collectively these data suggest that the metabolic regulator USF-1 is involved in the control of affective behaviour in mice and that this modulation of mood states is unrelated to USF-1-dependent BAT activation, but reflected in structural changes in the brain.