Systemic low-grade inflammation and subsequent depressive symptoms: Is there a mediating role of physical activity?

Associations between socioeconomic inequalities and progression to psychological and cognitive multimorbidities after onset of a physical condition: a multicohort study

Background

Chronic physical conditions (e.g., heart diseases, diabetes) increase with population ageing, contributing to psychological and cognitive multimorbidities. Yet, little is known about socioeconomic inequalities in this process. We examined the associations between socioeconomic status (SES) and progression to psychological and cognitive multimorbidities after onset of a physical condition.

Methods

We used harmonized individual-level data from five prospective cohort studies across 24 countries in the US, Europe and Asia, with repeated morbidity measurements between 2002 and 2021. Participants with at least one new-onset physical conditions (hypertension, diabetes, heart diseases, stroke, chronic lung diseases, cancer, or arthritis) were followed up for progression to physical-psychological multimorbidity, physical-cognitive multimorbidity, and physical-psychological-cognitive multimorbidity. SES was determined based on educational level and total household wealth at the onset of a physical condition. Time to and incidence rates of progressing psychological and cognitive multimorbidities were estimated in analyses stratified by SES. Fine-Gray subdistribution hazard models and multi-state models were used to estimate the associations between SES and progression to psychological and cognitive multimorbidities.

Findings

Among 20,250 participants aged ≥45 years (mean age at a physical condition onset 65.38 years, standard deviation 8.37) with at least one new-onset physical conditions in the analysis, 7928 (39.2%) progressed to psychological and cognitive multimorbidities during a median follow-up of 8.0 years (168,575 person-years). The mean survival time free from physical-psychological-cognitive multimorbidity was 11.96 years (95% confidence interval 11.57-12.34) in low SES individuals, compared to 15.52 years (15.40-15.63) in high SES individuals, with the corresponding incidence rate of 18.44 (16.32-20.82) and 3.15 (2.48-4.01) per 1000 person-years, respectively. The associations of education, household wealth and SES with multimorbidities followed a dose-dependent relation, with subdistribution hazard ratios per decreasing SES category being 1.24 (1.19-1.29) for physical-psychological multimorbidity, 1.47 (1.40-1.54) for physical-cognitive multimorbidity, and 1.84 (1.72-1.97) for physical-psychological-cognitive multimorbidity. The strongest SES-multimorbidities associations were observed in participants with arthritis, hypertension or diabetes. In multi-state models SES was linked to all five transitions from physical condition to physical-psychological multimorbidity, physical-cognitive multimorbidity and physical-psychological-cognitive multimorbidity.

Interpretation

Socioeconomic inequalities are associated with the progression of a chronic physical condition, with the lower SES groups had both an earlier time to and a higher incidence of psychological and cognitive multimorbidities. These findings underscore the need for more effective equity-oriented policies and healthcare practices to address reduced psychological wellness and cognitive maintenance among individuals with low SES and physical conditions.

Funding

Zhejiang University Hundred Talents Program Research Initiation Fund, Fundamental Research Funds for the Central Universities in China, Wellcome Trust, Medical Research Council, National Institute on Aging, Academy of Finland.

Depressive Symptoms, Socioeconomic Position, and Mortality in Older People Living With and Beyond Cancer

OBJECTIVE

Evidence shows that higher depressive symptoms are associated with mortality among people living with and beyond cancer (LWBC). However, prior studies have not accounted for a wider range of potential confounders, and no study has explored whether socioeconomic position (SEP) moderates the association. This study aimed to examine the association between depressive symptoms and mortality among people LWBC, and moderation by SEP.

METHODS

Participants from the English Longitudinal Study of Aging, diagnosed with cancer and with a measure of depressive symptoms within 4 years after their diagnosis, were included. Elevated depressive symptoms were indicated by a score of ≥3 on the eight-item Center for Epidemiologic Studies Depression Scale. Cox regression models examined associations with all-cause mortality. Competing risk regression examined associations with cancer mortality.

RESULTS

In 1352 people LWBC (mean age = 69.6 years), elevated depressive symptoms were associated with a 93% increased risk of all-cause mortality (95% confidence interval = 1.52-2.45) within the first 4 years of follow-up and a 48% increased risk within a 4- to 8-year follow-up (95% confidence interval = 1.02-2.13) after multivariable adjustment. Elevated depressive symptoms were associated with a 38% increased risk of cancer mortality, but not after excluding people who died within 1 year after baseline assessments. There were no interactions between depressive symptoms and SEP.

CONCLUSIONS

Elevated depressive symptoms are associated with a greater risk of all-cause mortality among people LWBC within an 8-year follow-up period. Associations between depressive symptoms and cancer mortality might be due to reverse causality.

Multiple trajectories of depressive symptoms among Chinese in middle and late life: Characterization and risk factors

BACKGROUND

Depressive symptoms, which are continuously changing, are an essential manifestation of depression and can increase the risk of mental disorders and other diseases. Because the causes and cures for depression have not yet been identified, finding the characteristics, and risk factors of depressive symptom trajectories can help us identify at-risk populations early and reduce the related public disease burden.

AIMS

Herein we aimed to figure out the specific manifestations of depressive symptom trajectories among Chinese adults, explore the risk profiles of trajectory groups with higher depression burdens, and test the longitudinal associations between blood biomarkers with depressive symptoms.

METHODS

Trajectories of participants' depressive symptoms measured by the Center for Epidemiologic Studies Depression scores were modeled with growth mixture models from 2011 to 2018. Multinomial logistic models tested associations of baseline covariates with trajectories. Generalized estimating equations were used to explore the longitudinal associations between blood data and depressive symptoms in two waves from 2011 to 2015.

RESULTS

Among the sample of 5,641 individuals aged 40 or over, four heterogeneous depressive symptom trajectories were defined: stable-low, high-decrease, stable-high, and low-increase. At baseline, demographic factors and health statuses such as gender, education, income, and self-reported health status were associated with trajectories. A significant association was found between high-density lipoprotein and depressive symptoms.

CONCLUSIONS

These findings provide clues for predicting and identifying adults with elevated depression burdens in middle and late life and may facilitate the development of targeted preventive strategies for this population.

Prevalence and clinical correlates of abnormal lipid metabolism in first-episode and drug-naïve patients with major depressive disorder: A large-scale cross-sectional study

OBJECTIVE

Studies have shown an association between abnormal lipid profiles and MDD, but there are few studies on the clinical correlates of lipid abnormalities in patients with major depressive disorder (MDD). The purpose of this study was to investigate the prevalence of abnormal lipid metabolism and its correlates in Chinese first-episode and drug-naïve MDD patients, which has not yet been reported.

METHODS

A total of 1718 outpatients with first-episode and drug-naïve MDD were included. Demographic data were collected by a standardized questionnaire and blood lipid levels were measured, including total cholesterol (TC), triglyceride (TG), low density lipoprotein (LDL-C), high density lipoprotein (HDL-C). The Hamilton Depression Scale (HAMD), Hamilton Anxiety Scale (HAMA), Positive and Negative Syndrome Scale (PANSS) positive subscale, and Clinical Global Impression of Severity Scale (CGI-S) were assessed for each patient.

RESULTS

The prevalence of abnormal lipid metabolism was 72.73% (1301/1718), and the rates of high TC, high TG, high LDL-C and low HDL-C were 51.05% (877/1718), 61.18% (1051/1718), 30.09% (517/1718), 23.40% (402/1718), respectively. Logistic regression showed the risk factors for abnormal lipid metabolism were severe anxiety, HAMD score, CGI-S score, BMI and systolic blood pressure (SBP). Multiple linear regression analysis showed that age at onset, SBP, HAMD score, HAMA score, PANSS positive subscale score, and CGI-S were independently associated with TC levels. BMI, HAMD score, PANSS positive subscale score and CGI-S score were independently associated with TG levels. SBP, HAMD score, PANSS positive subscale score and CGI-S score were independently associated with LDL-C levels. Age of onset, SBP and CGI-S score were independently associated with HDL-C levels.

CONCLUSIONS

The prevalence of abnormal lipid metabolism in first-episode and drug-naïve MDD patients is quite high. The severity of psychiatric symptoms may be closely associated with the presence of abnormal lipid metabolism in patients with MDD.

Phenolic compounds can induce systemic and central immunomodulation, which result in a neuroprotective effect

Inflammation may negatively impact health, particularly that of the central nervous system. Phenolic compounds are bioactive molecules present in fruits and vegetables with potential anti-inflammatory effects. The purpose of the present work is to review the immunomodulatory bioactivities of phenolic compounds in the periphery and in the central nervous system. Results show that various types of phenolics are able to counter diet- or pathogen-induced systemic inflammation (among others) in various models. In vitro data show significant effects of flavonoids and phenolic acids in particular; similar bioactivities were reported in vivo, when administering them as pure compounds or from fruit and vegetable extracts that contain them. In the central nervous system, phenolics counter chronic inflammation and aggressive acute inflammatory processes, such as ischemic events, when administered preemptively and even therapeutically. We therefore conclude that the immunomodulatory potential of phenolic compounds can maintain an adequate immune response; their regular consumption should therefore be prioritized in order to maintain health. PRACTICAL APPLICATIONS: The immune response must be carefully regulated in order to avoid its deleterious effects. The present work highlights how phenolic compounds, dietary components ubiquitous in everyday diet, are able to maintain it within an adequate range. As humans are exposed to more proinflammatory stimuli (inadequate dietary pattern, mental stress, environmental pollution, chronic diseases, etc.), it becomes necessary to counter them, and consuming adequate amounts of foods that contain compounds with this ability is a rather simple strategy. Thus, the present work highlights how fruits and vegetables can help to maintain an adequate immune response that can preserve systemic health and that of the central nervous system. Furthermore, specific compounds contained in them can also be ideal candidates for additional in-depth studies, which can potentially lead to the development of potent, targeted, and safe anti-inflammatory molecules.

Higher Plasma Fibrinogen Level at Admission Is Associated with Post-Stroke Depression at Discharge

Background: Post-stroke depression (PSD) is a common complication of stroke, which seriously affects the functional outcome of patients. Systemic low-grade inflammation associated with PSD has been shown to occur at several months to years, however, whether these inflammatory markers predicted PSD at an acute stage of stroke is controversial. Method: A total of 625 patients with acute ischemic stroke (219 female, 35.40%) were included in this study. PSD was diagnosed using the 17-item Hamilton depression scale (HAMD) at 7 days following discharge (7−14 days after stroke onset). Multivariable logistic regression analysis was applied to build a prediction model for PSD at discharge. Discrimination and calibration of the model were assessed by C-index, calibration plot. Internal validation was conducted using bootstrapping validation. Results: At discharge of hospitalization, 95 patients (15.20%) were diagnosed with PSD. Multivariable logistic regression suggested that female gender (OR = 2.043, 95% CI = 1.287−3.245, p = 0.002), baseline NIHSS (OR = 1.108, 95% CI = 1.055−1.165, p < 0.001) and fibrinogen (OR = 1.388, 95% CI = 1.129−1.706, p = 0.002) were independent predictors for PSD at discharge. The cut-off of the fibrinogen plasma level was 3.08 g/L. These predictors were included in the nomogram. The model displayed good discrimination, with a C-index of 0.730 (95% CI = 0.683−0.777) and good calibration. Conclusion: Female gender, baseline stroke severity and a higher level of fibrinogen were independently associated with PSD at discharge. A nomogram based on these three predictors can be used to provide an individual, visual prediction of the risk probability of PSD.

Physical activity and social support mediate the relationship between chronic diseases and positive mental health in a national sample of community-dwelling Canadians 65+: A structural equation analysis

BACKGROUND

Mental health is a critical component of healthy aging. Aging increases the likelihood of developing chronic diseases. The negative effects of chronic diseases on mental health have been extensively documented. Physical activity and social support have been reported to influence mental health positively.

METHODS

Data analyzed are drawn from the national Canadian Community Health Survey - Mental Health in 2012. Structural equation modeling (SEM) techniques were used to estimate and test the mediating role of physical activities and social support in the relationship between chronic disease, positive mental health, and psychological distress in a national adult population sample aged 65+.

RESULTS

Approximately 83% of the older adults sample reported having at least one chronic disease, and the mean score of psychological distress and positive mental health was 14.15 ± 4.73 and 55.28 ± 10.67, respectively. Initial analysis found that chronic illness was negatively related to positive mental health (β= -0.72, P < 0.001) and positively related to psychological distress (β=0.98, P < 0.001). The final structural model found that physical activity and social support partially mediated the negative consequences of chronic disease on psychological distress and strengthened seniors' positive mental health.

LIMITATIONS

Limiting causal attribution, potential reporting bias and limited in recognizing negative and positive social support are the major limitations.

CONCLUSIONS

Older adults with chronic diseases should be encouraged to increase physical activity and social support levels. The study outcomes have clinical implications for the delivery of mental health services to improve mental health and resilience to coping with stress among older adults.

Systemic low-grade inflammation and depressive symptomology at chronic phase of ischemic stroke: The chain mediating role of fibrinogen and neutrophil counts

BACKGROUND

Post-stroke depression (PSD) is the most common psychological consequence of stroke. Increased inflammatory markers resulting from ischemic stroke may played an important role in the pathogenesis of depressive symptomology. The present study was conducted to further elucidate the relationship between stroke severity, systemic low-grade inflammation and chronic phase post-stroke depressive symptomology (CP-PSDS).

METHODS

A total of 897 stroke patients were consecutively recruited in this multicenter prospective cohort study and followed up for 1 year. The analytical sample consisted of 436 patients with ischemic stroke (23.4% female, median age = 57 years) from this cohort. Serum concentrations of inflammatory markers were measured in all 436 patients with ischemic stroke, from fasting morning venous blood samples on admission. Stroke severity was evaluated using the National Institutes of Health Stroke Scale (NIHSS) on admission and post-stroke depressive symptomology (PSDS) was evaluated by 17-item Hamilton Rating Scale for Depression (HRSD).

RESULTS

In the fully adjusted models, we observed that 1) NIHSS (Model 2: β = 0.200, 95%CI, 0.057 ∼ 0.332), fibrinogen (Model 2: β = 0.828, 95%CI, 0.269 ∼ 1.435), white blood cell counts (WBC, model 2: β = 0.354, 95%CI, 0.122 ∼ 0.577) and neutrophil counts (Model 2: β = 0.401, 95%CI, 0.126 ∼ 0.655) can independently predict the CP-PSDS after ischemic stroke onset; 2) fibrinogen (Indirect effect = 0.027, 95%CI, 0.007 ∼ 0.063, 13.4% mediated), WBC (Indirect effect = 0.024, 95%CI, 0.005 ∼ 0.058, 11.8% mediated) and neutrophil counts (Indirect effect = 0.030, 95%CI, 0.006 ∼ 0.069, 14.8% mediated) could partially mediate the association between stroke severity and CP-PSDS, and 3) stroke severity might cause CP-PSDS partly through the chain-mediating role of both fibrinogen and neutrophil counts (chain mediated effect = 0.003, 95%CI, 0.000 ∼ 0.011, p = 0.025, 1.6% mediated).

CONCLUSIONS

Findings revealed that fibrinogen, WBC and neutrophil counts may be independent predictors of CP-PSDS and partial mediators of the relationship between stroke severity and CP-PSDS among patients with ischemic stroke. In addition, the chain mediating effect of fibrinogen and neutrophil counts might play an important role in the occurrence of CP-PSDS. However, no inflammatory markers were associated with CP-PSDS in females.

Association between the consumption of omega-3-rich fish and depressive symptoms in older adults living in a middle-income country: EpiFloripa Aging cohort study

This study aimed to verify the association between the consumption of omega-3-rich (n-3) fish and depressive symptoms in older adults living in Southern Brazil. This is a cross-sectional analysis with data from the second wave of the EpiFloripa Aging cohort study (2013/2014) including 1,130 individuals aged 60 years or older. The presence of depressive symptoms was measured by the 15-items Geriatric Depression Scale (GDS-15), and the consumption of n-3-rich fish by a question of weekly frequency. The minimum set of variables for adjustment was defined using directed acyclic graph (DAG). Poisson regression with robust error variance was applied (adjusted by Model 1: demographic and socioeconomic variables, Model 2: added behavioral variables, Model 3: added health variables). We identified the prevalence of depressive symptoms in 19% of older adults and 51.8% reported eating n-3-rich fish once a week. Models 1 and 3 showed an inverse association between n-3-rich fish and depressive symptoms. However, the association was reduced when behavioral factors (leisure-time physical activity) were included in Model 2. These findings suggest that n-3-rich fish intake tends to be associated with depressive symptoms in older adults. However, other factors, such as physical exercise, are as pivotal as n-3 fatty acids in preventing the development of depressive symptoms.

Immune targets for therapeutic development in depression: towards precision medicine

Over the past two decades, compelling evidence has emerged indicating that immune mechanisms can contribute to the pathogenesis of major depressive disorder (MDD) and that drugs with primary immune targets can improve depressive symptoms. Patients with MDD are heterogeneous with respect to symptoms, treatment responses and biological correlates. Defining a narrower patient group based on biology could increase the treatment response rates in certain subgroups: a major advance in clinical psychiatry. For example, patients with MDD and elevated pro-inflammatory biomarkers are less likely to respond to conventional antidepressant drugs, but novel immune-based therapeutics could potentially address their unmet clinical needs. This article outlines a framework for developing drugs targeting a novel patient subtype within MDD and reviews the current state of neuroimmune drug development for mood disorders. We discuss evidence for a causal role of immune mechanisms in the pathogenesis of depression, together with targets under investigation in randomized controlled trials, biomarker evidence elucidating the link to neural mechanisms, biological and phenotypic patient selection strategies, and the unmet clinical need among patients with MDD.

Does Low Grade Systemic Inflammation Have a Role in Chronic Pain?

One of the major clinical manifestations of peripheral neuropathy, either resulting from trauma or diseases, is chronic pain. While it significantly impacts patients’ quality of life, the underlying mechanisms remain elusive, and treatment is not satisfactory. Systemic chronic inflammation (SCI) that we are referring to in this perspective is a state of low-grade, persistent, non-infective inflammation, being found in many physiological and pathological conditions. Distinct from acute inflammation, which is a protective process fighting against intruders, SCI might have harmful effects. It has been associated with many chronic non-communicable diseases. We hypothesize that SCI could be a predisposing and/or precipitating factor in the development of chronic pain, as well as associated comorbidities. We reviewed evidence from human clinical studies indicating the coexistence of SCI with various types of chronic pain. We also collated existing data about the sources of SCI and who could have it, showing that those individuals or patients having SCI usually have higher prevalence of chronic pain and psychological comorbidities. We thus elaborate on the need for further research in the connection between SCI and chronic pain. Several hypotheses have been proposed to explain these complex interactions.

The effect of triglycerides in the associations between physical activity, sedentary behavior and depression: An interaction and mediation analysis

BACKGROUND

Previous studies reported that there were associations between physical activity (PA), sedentary behavior (SB), triglycerides (TG) and depression. However, it is unclear whether there is an interaction and/or mediation effect of TG in the associations between PA, SB and depression. This study was to explore the effects of TG in the associations between PA, SB and depression, respectively.

METHODS

Our study included 7,728 adults (aged ≥20 years) participating in the 2009-2018 National Health and Nutrition Examination Survey (NHANES), which was a nationally representative survey. With higher TG as a mediator, a four-way decomposition method was used to decompose the total effects of insufficient PA and prolonged SB on depression, respectively.

RESULTS

There were statistically significant associations between moderate-to-vigorous recreational activity (MVRA), SB, TG and depression (all P < 0.05), respectively. With higher TG as a mediator, there were interaction and mediation effects in the association between SB and depression, and the excess relative risk (95% CI) of reference interaction effect (INT_ref) and the total mediation effect were 0.15(0.01,0.29) and 0.03(0.00,0.06), respectively. While insufficient MVRA attributed a proportion of 80.42% for the controlled direct effect (CDE) and 6.28% for total mediation effect. In addition, similar findings were observed in those with hypertension, overweight/obesity, dyslipidemia, and metabolic syndromes.

LIMITATION

This was a cross-sectional study, and the ability to make causal inference was limited.

CONCLUSION

The controlled direct effect of MVRA, the mediation of TG, and the interaction between SB and TG played the vital roles in increasing the risk of depression.

Sex Differences in the Associations of Handgrip Strength and Asymmetry With Multimorbidity: Evidence From the English Longitudinal Study of Ageing

OBJECTIVES

To determine the sex-specific associations of handgrip strength (HGS) and asymmetry with incident multimorbidity and examine whether these relationships differ by sex.

DESIGN

Prospective cohort study.

SETTING AND PARTICIPANTS

Secondary analyses of data from the English Longitudinal Study of Ageing (ELSA, waves 2-8). The analytic sample included 3977 participants (51.4% female) aged ≥50 years who had data for HGS on both hands and were living without multimorbidity at baseline.

MEASURES

HGS was assessed with a handheld dynamometer. Individuals in the lowest tertile of sex-specific age-adjusted HGS were defined as having low HGS. The largest HGS readings from the nondominant and dominant hand were used to calculate HGS ratio [nondominant HGS (kg)/dominant HGS (kg)]. Those with HGS ratio <0.90 or >1.10 had any HGS asymmetry. Further, those with HGS ratio <0.90 had dominant HGS asymmetry, whereas those with HGS ratio >1.10 had nondominant HGS asymmetry. Multimorbidity was defined as the coexistence of ≥2 chronic diseases. Cox proportional hazards regression models were conducted for analyses.

RESULTS

Low HGS was associated with multimorbidity among older men [hazard ratio (HR) 1.20, 95% confidence interval (CI) 1.03-1.40] and women (HR 1.19, 95% CI 1.03-1.38). No significant effect modification by sex was observed (P-interaction = .71). HGS asymmetry increased the risk of multimorbidity in women only (HR 1.23, 95% CI 1.07-1.41). The relationship between HGS asymmetry and multimorbidity risk differed by sex (P-interaction = .01). Similarly, both dominant HGS asymmetry (HR 1.21, 95% CI 1.05-1.40) and nondominant HGS asymmetry (HR 1.32, 95% CI 1.03-1.68) were related to incident multimorbidity in women only. There was a significant interaction between dominant HGS asymmetry and sex (P-interaction = .02).

CONCLUSIONS AND IMPLICATIONS

Examining HGS asymmetry in HGS test protocols can provide novel insights for the predictive power of HGS in the accumulation of diseases, particularly in women.

Association between high-sensitivity C-reactive protein levels and depression: Moderation by age, sex, obesity, and aerobic physical activity

BACKGROUND

Low-grade systemic inflammation evidenced by elevated serum high-sensitivity C-reactive protein (hsCRP) levels can be a biomarker for depression. This study aimed to investigate the association between serum hsCRP levels and depressive symptoms and to explore the potential moderating effects of age, sex, body mass index (BMI), and aerobic physical activity on the association.

METHODS

Data of 10,702 adults (≥ 19 years) were obtained from the nationwide cross-sectional Korea National Health and Nutrition Examination Surveys of 2016 and 2018. Significant depressive symptoms were defined as ≥ 10 on the Patient Health Questionnaire-9, and high hsCRP level was defined as > 3.0 mg/L.

RESULTS

Adults with high hsCRP levels were more likely to have depressive symptoms (odds ratio [OR]: 1.41, 95% confidence interval [CI]: 1.07-1.84) and suicidal ideation (OR: 1.39, 95% CI: 1.07-1.80) than those with low hsCRP levels. In the age- and sex-stratified analysis, high hsCRP levels were associated with depressive symptoms in the non-geriatric population (age ≤ 64 years) alone, with a higher OR in males than females. In subgroup analyses, the association between them was observed only among obese adults and adults without aerobic physical activity.

LIMITATIONS

Causal interpretation is limited due to the cross-sectional design.

CONCLUSIONS

Our results replicate previous findings of an association between high hsCRP levels and depressive symptoms in adults using a large nationally representative sample. The association between them was more prominent in the non-geriatric population, males, obese adults, and those without aerobic physical activity.

Challenges in researching the immune pathways between early life adversity and psychopathology

Exposure to childhood adversity is a critical risk factor for the development of psychopathology. A growing field of research examines how exposure to childhood adversity is translated into biological risk for psychopathology through alterations in immune system functioning, most notably heightened levels of inflammation biomarkers. Though our knowledge about how childhood adversity can instantiate biological risk for psychopathology is growing, there remain many challenges and gaps in the field to understand how inflammation from childhood adversity contributes to psychopathology. This paper reviews research on the inflammatory outcomes arising from childhood adversity and presents four major challenges that future research must address: (a) the measurement of childhood adversity, (b) the measurement of inflammation, (c) the identification of mediators between childhood adversity and inflammation, and (d) the identification of moderators of inflammatory outcomes following childhood adversity. We discuss synergies and inconsistencies in the literature to summarize the current understanding of the association between childhood adversity, a proinflammatory phenotype, and the biological risk for psychopathology. We discuss the clinical implications of the inflammatory links between childhood adversity and psychopathology, including possibilities for intervention. Finally, this review conclude by delineates future directions for research, including issues of how best to detect, prevent, and understand these “hidden wounds” of childhood adversity.

Customary physical activity and odds of depression: a systematic review and meta-analysis of 111 prospective cohort studies

Objective

To explore whether physical activity is inversely associated with the onset of depression, we quantified the cumulative association of customary physical activity with incident depression and with an increase in subclinical depressive symptoms over time as reported from prospective observational studies.

Design

Systematic review and meta-analysis.

Data sources

MEDLINE, PsycINFO, PsycARTICLES and CINAHL Complete databases, supplemented by Google Scholar.

Eligibility criteria

Prospective cohort studies in adults, published prior to January 2020, reporting associations between physical activity and depression.

Study appraisal and synthesis

Multilevel random-effects meta-analysis was performed adjusting for study and cohort or region. Mixed-model meta-regression of putative modifiers.

Results

Searches yielded 111 reports including over 3 million adults sampled from 11 nations in five continents. Odds of incident cases of depression or an increase in subclinical depressive symptoms were reduced after exposure to physical activity (OR, 95% CI) in crude (0.69, 0.63 to 0.75; I2=93.7) and adjusted (0.79, 0.75 to 0.82; I2=87.6) analyses. Results were materially the same for incident depression and subclinical symptoms. Odds were lower after moderate or vigorous physical activity that met public health guidelines than after light physical activity. These odds were also lower when exposure to physical activity increased over time during a study period compared with the odds when physical activity was captured as a single baseline measure of exposure.

Conclusion

Customary and increasing levels of moderate-to-vigorous physical activity in observational studies are inversely associated with incident depression and the onset of subclinical depressive symptoms among adults regardless of global region, gender, age or follow-up period.

Does physical activity influence the association between depressive symptoms and low-grade inflammation in adults? A study of 8,048 adults

This study investigated whether physical activity (PA) influences the association between depression risk and low-grade inflammation. This was a cross-sectional study including 8,048 adults (18-59y). Depression symptoms were evaluated with the Beck depression inventory (BDI) and physical activity through the international physical activity questionnaire. Adults with infectious and inflammatory diseases were excluded. Blood samples were collected, including high sensitivity C-reactive protein (CRP), a marker of low-grade inflammation when ≥3mg/L. Additional measures of LDL-C, HDL-C, triglycerides and fasting glucose were also determined. Sex, chronological age, tobacco smoking, alcohol drinking, body mass index, dyslipidemia, high blood pressure and fasting glucose were used as covariates. Mediation models were conducted using the procedures of Karlson Holm Breen. Adults with elevated CRP (≥3mg/L) compared to those with low CRP (<3mg/L) presented with higher BDI scores [8.5%(95%CI:7.2%-10.1%) vs. 5.8%(95%CI:5.2-6.4)] as well as higher prevalence of physical inactivity 67.4% (95%CI:64.9-69.9) vs. 59.7% (95%CI:58.4-60.9). The prevalence of elevated CRP was highest in physically inactive adults with greater depression risk. Models revealed that physical activity risk explained 13% of the association between depression risk and elevated CRP (p=0.035), independently of potential confounders. Physical activity may reduce the association between depression symptoms and elevated CRP. Future longitudinal research is required to determine the directionality of the relationships observed.

Genetic susceptibility, inflammation and specific types of depressive symptoms: evidence from the English Longitudinal Study of Ageing

Genetic susceptibility to depression has been established using polygenic scores, but the underlying mechanisms and the potentially differential effects of polygenic scores on specific types of depressive symptoms remain unknown. This study examined whether systemic low-grade inflammation mediated the association between polygenic scores for depressive symptomatology (DS-PGS) and subsequent somatic versus cognitive-affective depressive symptoms. The sample consisted of 3510 men and women (aged 50+) recruited from the English Longitudinal Study of Ageing. DS-PGS were derived using the results of a recent genome-wide association study. Plasma C-reactive protein (CRP) was measured at wave 6 (2012/13). Depressive symptoms were assessed at wave 8 (2016/17), using the eight-item version of the Centre for Epidemiological Studies Depression Scale. Covariates (wave 2, 2004/05) included age, sex and ten principal components (PCs) to control for population stratification. Confirmatory factor analysis was performed to corroborate a previously identified two-factor structure of the CES-D, distinguishing between cognitive-affective and somatic symptoms. Longitudinal structural equation modelling was used to investigate the mediating role of CRP in the relationship between DS-PGS and cognitive-affective versus somatic symptoms. Our results showed that participants with a higher polygenic susceptibility to DS were significantly more likely to report cognitive-affective and somatic symptoms at follow-up. Mediation analyses revealed that CRP mediated the relationship between DS-PGS and somatic symptoms, but not the association between DS-PGS and cognitive-affective symptoms. These differential effects highlight the importance of considering individual differences in depression profiles in future studies. Ultimately, this will inform healthcare professionals to design more targeted treatments.