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Background: Regular physical activity reduces the risk of depression onset and is an effective treatment for mood disorders. Recent studies have reported that sedentary behavior (SB) increases the risk of depression in adults, but relationships of different types of SBs with depression have not been examined systematically. We explored longitudinal relationships of passive (e.g. watching TV) and mentally-active (e.g. office-work) SBs with incident major depressive disorder (MDD). Methods: Self-report questionnaires were completed by 40,569 Swedish adults in 1997; responses were linked to clinician-diagnosed MDD obtained from medical registers until 2010. Relationships between passive, mentally-active and total SBs with incident MDD were explored using survival analysis with Cox proportional hazards regression. Models controlled for leisure time moderate-vigorous physical activity and occupational physical activity. Moderating effects of gender were examined. Results: In fully-adjusted models, including only non-depressed adults at baseline, those reporting ≥ 3 h of mentally-active SBs on a typical day (versus < 3 h) had significant lower hazards of incident MDD at follow-up (HR = 0.74, 95% CI = 0.58–0.94, p = 0.018). There was a non-significant positive relationship of passive SBs with incident MDD (HR = 1.20, 95% CI = 0.96–1.52, p = 0.106). The association between total SBs (passive and mentally-active combined) was not significant (HR = 0.91, 95% CI = 0.75–1.10, p = 0.36). Gender did not moderate these associations. Limitations: Physical activity and SBs were self-reported. Conclusion: Mentally-active SBs may have beneficial effects on adults’ mental well-being. These effects are largely independent of habitual physical activity levels

Paired associative stimulation (PAS) can induce plasticity in the motor cortex, as measured by changes in corticospinal excitability (CSE). This effect is attenuated in older and less active individuals. Although a single bout of exercise enhances PAS-induced plasticity in young, physically inactive adults, it is not yet known if physical activity interventions affect PAS-induced neuroplasticity in middle-aged inactive individuals. Sixteen inactive middle-aged office workers participated in a randomized cross-over design investigating how CSE and short-interval intracortical inhibition (SICI) were affected by PAS preceded by 3 h of sitting (SIT), 3 h of sitting interrupted every 30 min by 3 min of frequent short bouts of physical activity (FPA) and 2.5 h of sitting followed by 25 min of moderate-intensity exercise (EXE). Transcranial magnetic stimulation was applied over the primary motor cortex (M1) of the dominant abductor pollicis brevis to induce recruitment curves before and 5 min and 30 min post-PAS. Linear mixed models were used to compare changes in CSE using time and condition as fixed effects and subjects as random effects. There was a main effect of time on CSE and planned within-condition comparisons showed that CSE was significantly increased from baseline to 5 min and 30 min post-PAS, in the FPA condition, with no significant changes in the SIT or EXE conditions. SICI decreased from baseline to 5 min post-PAS, but this was not related to changes in CSE. Our findings suggest that in middle-aged inactive adults, FPAs may promote corticospinal neuroplasticity. Possible mechanisms are discussed., Fysisk aktivitet och hälsosamma hjärnfunktioner bland kontorsarbetare. Delprojekt 2 Akuta interventioner

Background: As distinct from mentally-active sedentary behaviors (e.g. reading), passive sedentary behaviors (e.g. TV-viewing) have been linked to a higher risk of depression, but the underlying mechanisms are unclear. We examined the potential mediating role of sleep problems in prospective relationships of passive sedentary behaviors with major depressive disorder (MDD). Method: In 1997, 43 863 adults were surveyed and responses linked to clinician diagnoses of MDD until 2010. The questionnaire included items on sedentary behavior and sleep problems (Karolinska Sleep Questionnaire). Cox proportional hazard models and the ‘counterfactual approach’ were used to identify potential mediating effects of sleep problems in the association of passive sedentary behavior and MDD. Results: Of the total sample, 3,065 (7.6%) were excluded for having indications of depression at baseline. Of 33,116 participants with complete data (mean age = 51.3 years, SD = 15.7, 64% female); 472 (1.4%) incident cases of MDD were identified during the 13-year follow-up. In Cox regression analyses, higher durations of passive sedentary behavior (≥3 h/day versus <3 h/day) were associated with greater hazards of developing MDD (HR = 1.27; 95% CI = 1.01, 1.58). This relationship remained after adjusting for confounders (HR = 1.29; 95% CI = 1.03, 1.63). Adding sleep problems into the analysis significantly attenuated these relationships (HR = 1.25; 95% CI = 0.99, 1.57). The excess MDD relative risk of passive sedentary behaviors due to sleep problems was statistically significant. Limitations: Measures of sedentary behavior, physical activity and sleep were self-reported. Conclusion: Sleep problems appear to mediate detrimental associations of passive sedentary behavior with depression. Findings require further confirmation using objective measures.

Background Sedentary behaviour can be associated with poor mental health, but it remains unclear whether all types of sedentary behaviour have equivalent detrimental effects.Aims To model the potential impact on depression of replacing passive with mentally active sedentary behaviours and with light and moderate-to-vigorous physical activity. An additional aim was to explore these relationships by self-report data and clinician diagnoses of depression.Method In 1997, 43 863 Swedish adults were initially surveyed and their responses linked to patient registers until 2010. The isotemporal substitution method was used to model the potential impact on depression of replacing 30 min of passive sedentary behaviour with equivalent durations of mentally active sedentary behaviour, light physical activity or moderate-to-vigorous physical activity. Outcomes were self-reported depression symptoms (cross-sectional analyses) and clinician-diagnosed incident major depressive disorder (MDD) (prospective analyses).Results Of 24 060 participants with complete data (mean age 49.2 years, s.d. 15.8, 66% female), 1526 (6.3%) reported depression symptoms at baseline. There were 416 (1.7%) incident cases of MDD during the 13-year follow-up. Modelled cross-sectionally, replacing 30 min/day of passive sedentary behaviour with 30 min/day of mentally active sedentary behaviour, light physical activity and moderate-to-vigorous activity reduced the odds of depression symptoms by 5% (odds ratio 0.95, 95% CI 0.94-0.97), 13% (odds ratio 0.87, 95% CI 0.76-1.00) and 19% (odds ratio 0.81, 95% CI 0.93-0.90), respectively. Modelled prospectively, substituting 30 min/day of passive with 30 min/day of mentally active sedentary behaviour reduced MDD risk by 5% (hazard ratio 0.95, 95% CI 0.91-0.99); no other prospective associations were statistically significant.Conclusions Substituting passive with mentally active sedentary behaviours, light activity or moderate-to-vigorous activity may reduce depression

The development in research concerning sedentary behaviour has been rapid over the past two decades. This has led to the development of evidence and views that have become more advanced, diverse and, possibly, contentious. These include the effects of standing, the breaking up of prolonged sitting and the role of moderate-to-vigorous physical activity (MVPA) in the association between sedentary behaviour and health outcomes. The present aim is to report the views of experts (n = 21) brought together (one-day face-to-face meeting in 2018) to consider these issues and provide conclusions and recommendations for future work. Each topic was reviewed and presented by one expert followed by full group discussion, which was recorded, transcribed and analysed. The experts concluded that (a). standing may bring benefits that accrue from postural shifts. Prolonged (mainly static) standing and prolonged sitting are both bad for health; (b). 'the best posture is the next posture'. Regularly breaking up of sitting with postural shifts and movement is vital; (c). health effects of prolonged sitting are evident even after controlling for MVPA, but high levels of MVPA can attenuate the deleterious effects of prolonged sitting depending on the health outcome of interest. Expert discussion addressed measurement, messaging and future directions.

BACKGROUND: Living in walkable neighborhoods may provide long-term cardio-metabolic health benefits to residents. Little empirical research has examined the behavioral mechanisms in this relationship. In this longitudinal study, we examined the potential mediating role of physical activity (baseline and 12-year change) in the relationships of neighborhood walkability with 12-year changes in cardio-metabolic risk markers. METHODS: The Australian Diabetes, Obesity and Lifestyle study collected data from adults, initially aged 25+ years, in 1999-2000, 2004-05, and 2011-12. We used 12-year follow-up data from 2023 participants who did not change their address during the study period. Outcomes were 12-year changes in waist circumference, weight, systolic and diastolic blood pressure, fasting and 2-h postload plasma glucose, high-density lipoprotein cholesterol, and triglycerides. A walkability index was calculated, using dwelling density, intersection density, and destination density, within 1 km street-network buffers around participants' homes. Spatial data for calculating these measures were sourced around the second follow-up period. Physical activity was assessed by self-reported time spent in moderate-to-vigorous physical activity (including walking). Multilevel models, adjusting for potential confounders, were used to examine the total and indirect relationships. The joint-significance test was used to assess mediation. RESULTS: There was evidence for relationships of higher walkability with smaller increases in weight (P = 0.020), systolic blood pressure (P < 0.001), and high-density lipoprotein cholesterol (P = 0.002); and, for relationships of higher walkability with higher baseline physical activity (P = 0.020), which, in turn, related to smaller increases in waist circumference (P = 0.006), weight (P = 0.020), and a greater increase in high-density lipoprotein cholesterol (P = 0.005). There was no evidence for a relationship of a higher walkability with a cha