Cause or consequence? Understanding the role of cortisol in the increased inflammation observed in depression

Neurobiological Implications of Chronic Stress and Metabolic Dysregulation in Inflammatory Bowel Diseases

Chronic stress is a significant factor affecting modern society, with profound implications for both physical and mental health. Central to the stress response is cortisol, a glucocorticoid hormone produced by the adrenal glands. While cortisol release is adaptive in acute stress, prolonged exposure to elevated levels can result in adverse effects. This manuscript explores the neurobiological implications of chronic stress and its impact on metabolic dysregulation, particularly in the context of inflammatory bowel diseases (IBDs). The hypothalamic-pituitary-adrenal (HPA) axis regulates cortisol production, which influences metabolism, immune response, and neurobiology. Elevated cortisol levels are associated with the development and exacerbation of metabolic disorders like IBD and contribute to neurodegenerative processes, including cognitive impairments and increased susceptibility to psychiatric conditions. The interaction between cortisol and its receptors, particularly glucocorticoid receptors, underscores the complexity of these effects. This review aims to elucidate the mechanisms through which chronic stress and cortisol dysregulation impact metabolic health and neurobiological function, providing insights into potential therapeutic strategies for mitigating these effects.

Prenatal Stress and Ethanol Exposure: Microbiota-Induced Immune Dysregulation and Psychiatric Risks

Changes in maternal gut microbiota due to stress and/or ethanol exposure can have lasting effects on offspring's health, particularly regarding immunity, inflammation response, and susceptibility to psychiatric disorders. The literature search for this review was conducted using PubMed and Scopus, employing keywords and phrases related to maternal stress, ethanol exposure, gut microbiota, microbiome, gut-brain axis, diet, dysbiosis, progesterone, placenta, prenatal development, immunity, inflammation, and depression to identify relevant studies in both preclinical and human research. Only a limited number of reviews were included to support the arguments. The search encompassed studies from the 1990s to the present. This review begins by exploring the role of microbiota in modulating host health and disease. It then examines how disturbances in maternal microbiota can affect the offspring's immune system. The analysis continues by investigating the interplay between stress and dysbiosis, focusing on how prenatal maternal stress influences both maternal and offspring microbiota and its implications for susceptibility to depression. The review also considers the impact of ethanol consumption on gut dysbiosis, with an emphasis on the effects of prenatal ethanol exposure on both maternal and offspring microbiota. Finally, it is suggested that maternal gut microbiota dysbiosis may be significantly exacerbated by the combined effects of stress and ethanol exposure, leading to immune system dysfunction and chronic inflammation, which could increase the risk of depression in the offspring. These interactions underscore the potential for novel mental health interventions that address the gut-brain axis, especially in relation to maternal and offspring health.

A systematic review and meta-analysis of cortisol levels in Plasmodium infections

Malaria has complex interactions with host physiology, including alterations in cortisol levels. Cortisol, a key hormone in the stress response, is known to be dysregulated in various infectious diseases. This systematic review and meta-analysis aimed to elucidate the relationship between Plasmodium infection and cortisol levels, shedding light on the intricate interplay between the parasite and the host's endocrine system. The methodological protocol for assessing cortisol levels in malaria patients was registered in PROSPERO (CRD42024496578), a widely recognized international prospective register of systematic reviews. This registration ensures transparency and minimizes the risk of bias in our research. A comprehensive search strategy was employed across major databases, including Embase, PubMed, Scopus, and Medline, to include studies that reported cortisol levels in infected patients. The qualitative synthesis was undertaken to synthesize the difference in cortisol levels between malaria-infected and uninfected individuals. The meta-analysis employed the random effects model in the quantitative synthesis to calculate the effect estimate. The review included a total of 20 studies, with a substantial number conducted in Africa, followed by Asia and South America. Most included studies (13/20, 65%) reported higher cortisol levels in infected patients than in uninfected patients. The meta-analysis confirmed significantly higher cortisol levels in infected patients compared to uninfected individuals (P < 0.0001, standardized mean difference (SMD): 1.354, 95% confidence interval: 0.913 to 1.795, I2: 88.3%, across 15 studies). Notably, the method for cortisol measurement and the type of blood sample used (serum or plasma) were significant moderators in the analysis, indicating that these factors may influence the observed relationship between Plasmodium infection and cortisol levels. The systematic review and meta-analysis confirmed that Plasmodium infection is associated with increased cortisol levels, highlighting the intricate relationship between the disease and the host stress response. These findings underscore the potential of cortisol as a supplementary biomarker for understanding the pathophysiological impact of malaria. By providing insights into the stress-related mechanisms of malaria, this comprehensive understanding can inform future research and potentially enhance disease management and treatment strategies, particularly in regions heavily burdened by malaria.

Neurobiology and systems biology of stress resilience

Stress resilience is the phenomenon that some people maintain their mental health despite exposure to adversity or show only temporary impairments followed by quick recovery. Resilience research attempts to unravel the factors and mechanisms that make resilience possible and to harness its insights for the development of preventative interventions in individuals at risk for acquiring stress-related dysfunctions. Biological resilience research has been lagging behind the psychological and social sciences but has seen a massive surge in recent years. At the same time, progress in this field has been hampered by methodological challenges related to finding suitable operationalizations and study designs, replicating findings, and modeling resilience in animals. We embed a review of behavioral, neuroimaging, neurobiological, and systems biological findings in adults in a critical methods discussion. We find preliminary evidence that hippocampus-based pattern separation and prefrontal-based cognitive control functions protect against the development of pathological fears in the aftermath of singular, event-type stressors [as found in fear-related disorders, including simpler forms of posttraumatic stress disorder (PTSD)] by facilitating the perception of safety. Reward system-based pursuit and savoring of positive reinforcers appear to protect against the development of more generalized dysfunctions of the anxious-depressive spectrum resulting from more severe or longer-lasting stressors (as in depression, generalized or comorbid anxiety, or severe PTSD). Links between preserved functioning of these neural systems under stress and neuroplasticity, immunoregulation, gut microbiome composition, and integrity of the gut barrier and the blood-brain barrier are beginning to emerge. On this basis, avenues for biological interventions are pointed out.

Exploring the Therapeutic Potential of Terpenoids for Depression and Anxiety

This review focus on the terpenoids as potential therapeutic agents for depression and anxiety disorders, which naturally found in a variety of plants and exhibit a wide range of biological activities. Among the terpenoids discussed in this review are α-pinene, β-caryophyllene, α-phellandrene, limonene, β-linalool, 1, 8-cineole, β-pinene, caryophyllene oxide, p-cymene, and eugenol. All of these compounds have been studied extensively regarding their pharmacological properties, such as neuroprotective effect, anti-inflammation, antibacterial, regulation of neurotransmitters and antioxidant effect. Preclinical evidence are reviewed to highlight their diverse mechanisms of action and therapeutic potential to support antidepressant and anxiolytic properties. Additionally, challenges and future directions are also discussed to emphasize therapeutic utility of terpenoids for mental health disorders. Overall, this review provides a promising role of terpenoids as novel therapeutic agents for depression and anxiety, with potential implications for the development of more effective and well-tolerated treatments in the field of psychopharmacology.

The Association Between Diets With High Inflammatory Potential and Sleep Quality and Its Parameters: A Systematic Review

CONTEXT

Dietary components or its overall properties can influence an individual's sleep status.

OBJECTIVE

The aim for this study was to critically search, appraise, and synthesize research evidence on the association between dietary inflammatory index (DII) and sleep quality and its parameters.

DATA SOURCES

Original published studies on adults were obtained from the PubMed, SCOPUS, ScienceDirect, Cochrane Library, and Google Scholar databases.

DATA EXTRACTION

The search was conducted without date limitation until April 2023. Duplicated and irrelevant investigations were screened out, and the results of the remaining articles were descriptively summarized, then critically appraised and analyzed. Possible mechanistic pathways regarding diet, systemic inflammation, and sleep status were discussed.

DATA ANALYSIS

Of the 102 studies searched, 23 articles (n = 4 cohort studies, 18 cross-sectional studies, and 1 intervention study) were included in the final review. The association between DII and sleep status was investigated subjectively in 21 studies and objectively in 6 studies. The main studied sleep outcomes were sleep quality, duration, latency, efficiency, apnea, disturbances, the use of sleeping medications, daytime dysfunctions, wakefulness after sleep onset, and rapid eye movement.

CONCLUSIONS

According to most of the evidence, DII may not be related to overall sleep quality, sleep duration, latency, efficiency, and the use of sleeping medications. The evidence of positive association was greater between a high DII score (pro-inflammatory diet) with daytime dysfunctions, wakefulness after sleep onset, and sleep apnea. There is insufficient evidence to make any conclusion regarding sleep disturbances and rapid eye movement.

Mediation of the association between depression and coronary heart disease by metabolic syndrome components

BACKGROUND

Depression is associated with incident coronary heart disease (CHD) via a pathway that may be causal, but the mechanisms underlying this association are unclear. We assessed the extent to which metabolic syndrome (MetS) and its components (i.e., elevated waist circumference, low high-density lipoprotein [HDL] cholesterol, elevated triglycerides, elevated blood pressure, and elevated fasting plasma glucose) may mediate this association.

METHODS

Data were Framingham Heart Study Research Materials obtained from the National Heart, Lung, and Blood Institute (NHLBI) Biologic Specimen and Data Repository Information Coordinating Center. We used Cox proportional hazards regression to estimate adjusted hazard ratios (aHR) representing the total effect (aHRTE) of probable depression, measured via the Centers for Epidemiological Studies - Depression scale, on incident CHD over approximately 18 years. Using inverse odds ratio weighting, we decomposed this estimate into natural direct effects (aHRNDE) and natural indirect effects (aHRNIE) through potential mediators (measured approximately three years after depression).

RESULTS

Probable depression was associated with incident CHD (aHRTE=1.45, 95% confidence interval [CI]: 0.93, 2.25), and elevated waist circumference partially mediated this association (aHRNDE=1.34, 95% CI: 0.76-2.32; aHRNIE=1.08, 95% CI: 0.63-1.91). We did not find evidence of additional mediation by additional MetS components.

CONCLUSIONS

Elevated waist circumference appears to play a role in the association between depression and CHD.

Mind the Gap: Unraveling the Intricate Dance Between Alzheimer's Disease and Related Dementias and Bone Health

PURPOSE OF REVIEW

This review examines the linked pathophysiology of Alzheimer's disease/related dementia (AD/ADRD) and bone disorders like osteoporosis. The emphasis is on "inflammaging"-a low-level inflammation common to both, and its implications in an aging population.

RECENT FINDINGS

Aging intensifies both ADRD and bone deterioration. Notably, ADRD patients have a heightened fracture risk, impacting morbidity and mortality, though it is uncertain if fractures worsen ADRD. Therapeutically, agents targeting inflammation pathways, especially Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) and TNF-α, appear beneficial for both conditions. Additionally, treatments like Sirtuin 1 (SIRT-1), known for anti-inflammatory and neuroprotective properties, are gaining attention. The interconnectedness of AD/ADRD and bone health necessitates a unified treatment approach. By addressing shared mechanisms, we can potentially transform therapeutic strategies, enriching our understanding and refining care in our aging society. This review article is part of a series of multiple manuscripts designed to determine the utility of using artificial intelligence for writing scientific reviews.

Cool the Inflamed Brain: A Novel Anti-inflammatory Strategy for the Treatment of Major Depressive Disorder

BACKGROUND

Abundant evidence suggests that inflammatory cytokines contribute to the symptoms of major depressive disorder (MDD) by altering neurotransmission, neuroplasticity, and neuroendocrine processes. Given the unsatisfactory response and remission of monoaminergic antidepressants, anti-inflammatory therapy is proposed as a feasible way to augment the antidepressant effect. Recently, there have been emerging studies investigating the efficiency and efficacy of anti-inflammatory agents in the treatment of MDD and depressive symptoms comorbid with somatic diseases.

METHODS

In this narrative review, prospective clinical trials focusing on anti-inflammatory treatment for depression have been comprehensively searched and screened. Based on the included studies, we summarize the rationale for the anti-inflammatory therapy of depression and discuss the utilities and confusions regarding the anti-inflammatory strategy for MDD.

RESULTS

This review included over 45 eligible trials. For ease of discussion, we have grouped them into six categories based on their mechanism of action, and added some other anti-inflammatory modalities, including Chinese herbal medicine and non-drug therapy. Pooled results suggest that anti-inflammatory therapy is effective in improving depressive symptoms, whether used as monotherapy or add-on therapy. However, there remain confusions in the application of anti-inflammatory therapy for MDD.

CONCLUSION

Based on current clinical evidence, anti-inflammatory therapy is a promisingly effective treatment for depression. This study proposes a novel strategy for clinical diagnosis, disease classification, personalized treatment, and prognostic prediction of depression. Inflammatory biomarkers are recommended to be assessed at the first admission of MDD patients, and anti-inflammatory therapy are recommended to be included in the clinical practice guidelines for diagnosis and treatment. Those patients with high levels of baseline inflammation (e.g., CRP > 3 mg/L) may benefit from adjunctive anti-inflammatory therapy.

Adrenal Incidentalomas and Other Endocrine-Related Adenomas: How Much Does Cortisol Secretion Matter?

Background: Adrenal incidentalomas (AI) are frequent findings in clinical practice. About 40% of AIs are associated with hypercortisolism of variable severity. Although mild autonomous cortisol secretion (MACS) has been associated with the impaired clinical outcome of several diseases, its effect on the development of benign neoplasms is unknown. Aim: To compare the prevalence of adenomas (thyroid, parathyroid, pituitary and other locations) in patients with nonfunctioning AIs (NFAIs) and MACS. Methods: A multicenter, retrospective study of patients with AIs evaluated in four tertiary hospitals was performed. Results: A total of 923 patients were included. Most patients were male (53.6%), with a mean age at diagnosis of 62.4 ± 11.13 years; 21.7% presented with bilateral AIs. MACS was observed in 29.9% (n = 276) of patients, while 69.9% (n = 647) were NFAIs. Adenomas in locations other than the adrenal gland were observed in 36% of the studied population, with a similar distribution in patients with MACS and NFAIs (33% vs. 32%; p > 0.05). There were no statistically significant differences in the prevalence of pituitary, thyroid, parathyroid or other endocrine-related adenomas between both groups, but the prevalence of metabolic comorbidities and mortality was increased in patients with MACS, specifically in patients with thyroid and other endocrine-related adenomas (p < 0.05). Conclusions: Adenomas in locations other than the adrenal glands occur in one third of patients with AIs. Mild autonomous hypercortisolism does not affect the prevalence of other endocrine-related adenomas but is associated with increased metabolic comorbidities and mortality, especially in patients with thyroid adenomas and adenomas in other locations.

Circadian regulation of hippocampal function is disrupted with corticosteroid treatment

Disrupted circadian activity is associated with many neuropsychiatric disorders. A major coordinator of circadian biological systems is adrenal glucocorticoid secretion which exhibits a pronounced preawakening peak that regulates metabolic, immune, and cardiovascular processes, as well as mood and cognitive function. Loss of this circadian rhythm during corticosteroid therapy is often associated with memory impairment. Surprisingly, the mechanisms that underlie this deficit are not understood. In this study, in rats, we report that circadian regulation of the hippocampal transcriptome integrates crucial functional networks that link corticosteroid-inducible gene regulation to synaptic plasticity processes via an intrahippocampal circadian transcriptional clock. Further, these circadian hippocampal functions were significantly impacted by corticosteroid treatment delivered in a 5-d oral dosing treatment protocol. Rhythmic expression of the hippocampal transcriptome, as well as the circadian regulation of synaptic plasticity, was misaligned with the natural light/dark circadian-entraining cues, resulting in memory impairment in hippocampal-dependent behavior. These findings provide mechanistic insights into how the transcriptional clock machinery within the hippocampus is influenced by corticosteroid exposure, leading to adverse effects on critical hippocampal functions, as well as identifying a molecular basis for memory deficits in patients treated with long-acting synthetic corticosteroids.