Unhealthy lifestyle impacts on biological systems involved in stress response: hypothalamic-pituitary-adrenal axis, inflammation and autonomous nervous system

Association between cigarette smoking and the risk of major psychiatric disorders: a systematic review and meta-analysis in depression, schizophrenia, and bipolar disorder

Background

The prevalence of cigarette smoking among patients with major psychiatric conditions is significantly higher than that in the general population. However, whether there is a causal association between cigarette smoking and major psychiatric disorders remains unclear. Therefore, we conducted a systematic review and meta-analysis of cohort studies to elucidate the association between cigarette smoking and the risk of major psychiatric disorders, including depression, schizophrenia, and bipolar disorder.

Methods

We systematically searched PubMed, Embase, and the Cochrane Library for potentially eligible studies from their inception until March 2, 2024. All pooled analyses were performed using a random-effects model, and exploratory sensitivity and subgroup analyses were conducted.

Results

Twenty-five cohort studies involving 2,917,030 individuals were included in the meta-analysis. The summary results indicated that both current smoking (relative risk [RR], 1.30; 95% confidence interval [CI], 1.18-1.43; P < 0.001) and former smoking (RR, 1.16; 95% CI, 1.09-1.23; P < 0.001) were associated with an elevated risk of major depression. Additionally, current smoking was significantly associated with an elevated risk of schizophrenia (RR, 1.84; 95% CI, 1.07-3.19; P = 0.028) and bipolar disorder (RR, 1.54; 95% CI, 1.22-1.95; P < 0.001).

Conclusion

Current smoking is significantly associated with an elevated risk of major psychiatric disorders, including major depression, schizophrenia, and bipolar disorder. Former smokers also have an elevated risk of major depression. However, it should be noted that, despite these significant associations, due to the nature of the cohort studies included, this study cannot establish a causal relationship between cigarette smoking and major psychiatric disorders.

Systematic review registration

https://inplasy.com/inplasy-2024-3-0093/, identifier INPLASY202430093.

A low n-6/n-3 PUFA ratio and high level of dietary ɑ-linolenic acid improves sleep behavior in mice with insomnia

Camelina sativa oil (CSO) and Semen Ziziphi Spinosae oil (SZSO) are functional oils that have beneficial effects on brain health. This study evaluated the sedative and hypnotic effects of vegetable oils with various n - 6/n - 3 polyunsaturated fatty acids (PUFA) ratios and ɑ-linolenic acid (ALA) contents to mice. The n - 6/n - 3 PUFA ratios of CSO (CSO:SZSO = 1:0, 1.8 g/kg), SZSO (CSO:SZSO = 0:1, 1.8 g/kg), CSO-SZSO-L (CSO:SZSO = 1:1, 1.8 g/kg), and CSO-SZSO-H (CSO:SZSO = 1:1, 3.6 g/kg) were 0.51, 140, 1.69, and 1.69, respectively. The doses of ALA administered to mice with p-chlorophenylalanine-induced insomnia were approximately 0.64, 50 × 10-4, 0.32, and 0.64 g/kg, respectively. The mice were administered CSO, SZSO, and a low-dose combination of CSO and SZSO for seven days with no obvious hypnotic effects. However, the administration of a high-dose combination of CSO and SZSO significantly prolonged sleep duration in mice with induced insomnia and inhibited the serum levels of corticotropin-releasing hormone, adrenocorticotropic hormone, and cortisol. Interestingly, there were no significant effects on the structure and function of the hippocampal tissue. The results indicated that the anti-insomnia effects of these vegetable oils were positively correlated with a low n - 6/n - 3 PUFA ratio and the absolute amount of ALA.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-024-06004-1.

Interplay of G-proteins and Serotonin in the Neuroimmunoinflammatory Model of Chronic Stress and Depression: A Narrative Review

INTRODUCTION

This narrative review addresses the clinical challenges in stress-related disorders such as depression, focusing on the interplay between neuron-specific and pro-inflammatory mechanisms at the cellular, cerebral, and systemic levels.

OBJECTIVE

We aim to elucidate the molecular mechanisms linking chronic psychological stress with low-grade neuroinflammation in key brain regions, particularly focusing on the roles of G proteins and serotonin (5-HT) receptors.

METHODS

This comprehensive review of the literature employs systematic, narrative, and scoping review methodologies, combined with systemic approaches to general pathology. It synthesizes current research on shared signaling pathways involved in stress responses and neuroinflammation, including calcium-dependent mechanisms, mitogen-activated protein kinases, and key transcription factors like NF-κB and p53. The review also focuses on the role of G protein-coupled neurotransmitter receptors (GPCRs) in immune and pro-inflammatory responses, with a detailed analysis of how 13 of 14 types of human 5-HT receptors contribute to depression and neuroinflammation.

RESULTS

The review reveals a complex interaction between neurotransmitter signals and immunoinflammatory responses in stress-related pathologies. It highlights the role of GPCRs and canonical inflammatory mediators in influencing both pathological and physiological processes in nervous tissue.

CONCLUSION

The proposed Neuroimmunoinflammatory Stress Model (NIIS Model) suggests that proinflammatory signaling pathways, mediated by metabotropic and ionotropic neurotransmitter receptors, are crucial for maintaining neuronal homeostasis. Chronic mental stress can disrupt this balance, leading to increased pro-inflammatory states in the brain and contributing to neuropsychiatric and psychosomatic disorders, including depression. This model integrates traditional theories on depression pathogenesis, offering a comprehensive understanding of the multifaceted nature of the condition.

Antidepressants and type 2 diabetes: highways to knowns and unknowns

Type 2 diabetes (T2D) is a metabolic disease caused by the development of insulin resistance (IR), relative insulin deficiency, and hyperglycemia. Hyperglycemia-induced neurochemical dysregulation activates the progression of depression in T2D patients. Therefore, management of depression by antidepressant agents improves glucose homeostasis and insulin sensitivity. However, prolong use of antidepressant drugs may increase the risk for the development of T2D. However, there is strong controversy concerning the use of antidepressant drugs in T2D. Therefore, this review try to elucidate the potential effects of antidepressant drugs in T2D regarding their detrimental and beneficial effects.