This MR study explored the causal association between negative moods and CVDs. Our study demonstrated a significant positive correlation between genetic liability to tiredness and depressed mood with CAD and MI. However, there was a lack of empirical evidence suggesting genetically predicted tenseness, unenthusiasm, anxiety and, anger were causally associated with CVDs risk. In the reverse MR study, the results indicated no causal association between CAD, MI and negative mood risk. Using MVMR analyses, our study revealed an independent association between tiredness and CAD as well as MI. However, this effect was diminished when adjusting for diastolic blood pressure (DBP) or total cholesterol (TC). Additionally, after adjusting risk traits related to cardiovascular disease, the casual effect between depressed mood and CVDs disappeared. Other cardiovascular risk factors may contribute to the impact of depressed mood on CVDs.
Multiple systematic reviews and prospective analyses have suggested that psychosocial fact independently forecasts the occurrence of coronary heart disease in initially healthy populations, regardless of conventional risk factors [40, 41]. But there is still no consensus on which emotions cause cardiovascular disease. Previous research had yielded inconsistent findings regarding the association between tiredness and cardiovascular diseases. Williams et al. conducted a study involving a diverse group of participants without preexisting heart disease and discovered that both depressed mood and tiredness were strong predictors of developing cardiac events [42]. However, a prospective study focusing on the treatment of exhaustion in Angioplasty patients and its impact on the occurrence of new cardiac events did not confirm the effectiveness of behavioral intervention in reducing the risk (RR: 0.34; 95% CI: 0.11–1.07; P = 0.07) [11]. Various negative moods exhibit varying degrees of predictive ability for incident or recurrent cardiac events. A comprehensive meta-analysis of 30 prospective studies revealed a significant association between depressed mood and both coronary artery disease (RR: 1.30; 95% CI: 1.22–1.40) and myocardial infarction (RR: 1.30; 95% CI:1.18–1.44) risk [43]. Accordingly, as Pedersen and Zimmermann discovered, depressed mood following percutaneous coronary angioplasty predicts adverse cardiac events, fatigue did not demonstrate the same predictive capacity [44, 45]. Appels et al. found that AMI was predicted by fatigue in men without heart disease, while depressed mood was not a significant predictor of AMI when tiredness was taken into account. Above all, these results indicated the potentially pivotal role of negative moods, especially tiredness, depressed mood, tenseness, unenthusiasm, anxiety, and anger, in the pathogenesis of CVD and corresponding major adverse cardiovascular events (MACEs). However, the causal relationship between negative moods and clinical outcomes remained to be unclear by conventional observational studies, limited by their lower. Therefore, we chose six negative moods that may have resulted in CVDs using MR study.
In our study, we initially employed MR analysis to investigate the causal relationship between six negative moods and CVDs. Tiredness, especially mental fatigue, is a psychobiological condition resulting from extended periods of demanding cognitive tasks [46, 47]. This state has significant implications for various facets of everyday life. Numerous comprehensive prospective studies have demonstrated that tiredness is a predictor of the CVDs [48–52]. Our findings indicate that tiredness can serve as an independent predictor for CAD and MI, which aligns with the conclusions drawn by Williams et al. Furthermore, we conducted sensitivity analyses and intervened on potential cardiovascular risk factors to ensure the robustness of our evaluation. However, a prospective study focusing on the treatment of exhaustion in Angioplasty patients did not confirm the existence of a causal relationship [11]. This discrepancy may be attributed to the fact that fatigued patients tend to seek more medical assistance and adhere to secondary prevention measures. The potential mechanism underlying the association between tiredness and CVDs is proposed to involve serological markers of inflammation, such as heightened leukocyte adhesiveness/aggregation and elevated levels of interleukin (IL-6, IL-10), tumor necrosis factor, and C-reactive protein [53]. Additionally, it has been proposed that tiredness plays an important role in the dysregulation of the hypothalamus-pituitary-adrenal (HPA) axis as a result of prolonged exposure to stress, leading to reduced levels of the adrenocorticotropic hormone, decreased cortisol levels, and diminished concentrations of thyroid hormones [54].
We also demonstrated a causal relationship between depressed mood and CAD and MI, which is consistent with previous MR studies. The pathophysiological process of depressed mood is multifaceted, involving higher body composition traits, hypertension, endothelial dysfunction, and increased sympathetic excitability. A meta-analysis corroborated these findings by revealing shared risk factors, such as interleukin-6, C-reactive protein, and serum lipids, between depressed mood and coronary artery disease, aligning with clinical observations [55–61]. However, after adjusting for potential confounders in MVMR, the causal relationship disappeared. This discrepancy may be attributed to selection bias. Firstly, the subjects we studied primarily had depressed mood, and the causal effect on cardiovascular disease may not be as strong. Secondly, emotions are often influenced by numerous confounding factors. Our findings do not contradict previous MR studies. In contrast, our study further established a causal association between depression and CAD/MI. Observational studies have consistently reported an association between mental health and stroke, including both ischemic and hemorrhagic types. However, our study did not find any causal relationship between genetic predisposition to negative moods and the overall risk of stroke and its subtypes. Furthermore, we employed a bidirectional MR study design to mitigate the impact of reverse causality and minimize residual confounding. Consequently, the causal relationship between genetic susceptibility to CAD, MI, and negative moods remains unproven.
Our study encompasses several strengths. Firstly, we explored the correlation between genetically determined negative moods and cardiovascular diseases using MR methods, incorporating multiple sensitivity analyses and intervening on potential cardiovascular risk factors to ensure the robustness of our findings. Secondly, by utilizing genetically determined instrumental variables, we aimed to mitigate the impact of confounding factors and reverse causality commonly encountered in observational studies. The utilization of MR analysis facilitates a more robust causal inference regarding the relationship between tiredness, depressed mood, and the risk of CAD. Lastly, the implementation of MVMR analyses was employed to counteract the biases of confounding factors and reverse causal relationships, thereby aiding in the elucidation of relationships observed in univariable analyses.
However, our research encountered several limitations. Firstly, it was challenging to completely eliminate the possibility of pleiotropy, which was an inherent constraint in the MR analysis. Nonetheless, we mitigated this limitation by adjusting for other traits in our MVMR, and the sensitivity analyses produced consistent and reliable outcomes. Secondly, the statistical power of our investigation fell short of the desired 80% when examining the impact of six negative moods on the risk of stroke and its subtypes (Supplementary Table 11). Insufficient sample size and low variability in exposures may account for this inadequacy. Furthermore, the present study solely examined the correlation between negative moods and the risk of CVDs from a genetic perspective. Lastly, uncertainty remains regarding the applicability of these findings to other populations, considering that study participants were of European ancestry.