Causal relationships between dietary habits and five major mental disorders: A two-sample Mendelian randomization study

Dietary habit helps improve people's adaptability to hot climates: a case study of hotpot in Chongqing, China

Global warming has raised significant concerns about mitigation and adaptation strategies in recent years. This study investigated if consuming spicy food can help improve people's adaptability to hot environment. Onsite measurement and thermal questionnaires were conducted at Chongqing university in summer and winter aged 18 ∼ 30 years old. Participants were categorized into two groups, including frequently eating hotpot (Group-yes) and not (Group-no), and there were respectively 590 and 570 surveys. The results indicated that: (1) Eating hotpot could lower expectations of meteorological conditions. (2) It can decrease thermal sensitivity and expand neutral physiologically equivalent temperature (PET) range (14.89 ∼ 24.74 ℃ in Group-yes and 16.66 ∼ 23.98 ℃ in Group-no). (3) The acceptable PET range in Group-yes was 5.46 ℃ wider than Group-no with a higher preferred PET in Group-yes (24.04 ℃) compared to Group-no (22.63 ℃). (4) Respondents' thermal perception in Group-yes demonstrated a less susceptibility to meteorological variations compared to Group-no, and respondents in Group-no were more influenced by RH in summer. These findings suggest that consuming hotpot can improve thermal adaptation, thereby underscoring the significant influence of dietary habits on thermal adaptability.

Triangulated evidence provides no support for bidirectional causal pathways between diet/physical activity and depression/anxiety

BACKGROUND

Previous studies (various designs) present contradicting insights on the potential causal effects of diet/physical activity on depression/anxiety (and vice versa). To clarify this, we employed a triangulation framework including three methods with unique strengths/limitations/potential biases to examine possible bidirectional causal effects of diet/physical activity on depression/anxiety.

METHODS

Study 1: 3-wave longitudinal study (n = 9,276 Dutch University students). Using random intercept cross-lagged panel models to study temporal associations. Study 2: cross-sectional study (n = 341 monozygotic and n = 415 dizygotic Australian adult twin pairs). Using a co-twin control design to separate genetic/environmental confounding. Study 3: Mendelian randomization utilizing data (European ancestry) from genome-wide association studies (n varied between 17,310 and 447,401). Using genetic variants as instrumental variables to study causal inference.

RESULTS

Study 1 did not provide support for bidirectional causal effects between diet/physical activity and symptoms of depression/anxiety. Study 2 did provide support for causal effects between fruit/vegetable intake and symptoms of depression/anxiety, mixed support for causal effects between physical activity and symptoms of depression/anxiety, and no support for causal effects between sweet/savoury snack intake and symptoms of depression/anxiety. Study 3 provides support for a causal effect from increased fruit intake to the increased likelihood of anxiety. No support was found for other pathways. Adjusting the analyses including diet for physical activity (and vice versa) did not change the conclusions in any study.

CONCLUSIONS

Triangulating the evidence across the studies did not provide compelling support for causal effects of diet/physical activity on depression/anxiety or vice versa.

Relationship Between Food Addiction, Night Eating Syndrome and Depression Level in University Students and Affecting Factors: A Cross-Sectional Study in Türkiye

Food addiction, night eating, and depression levels alone have been associated with obesity and various chronic diseases in university students, but the relationship of these factors has been rarely mentioned in the literature. This research was conducted to determine the food addiction, night eating, and depression status of university students. The study consisted of 1009 (84.2% female, mean BMI 21.93 ± 3.42 kg/m2, 73.0% normal body weight) university students. Research data were collected using a web-based questionnaire, which included a personal information form about students' sociodemographic characteristics, nutritional habits and anthropometric measurements (body weight, height), the Yale Food Addiction Scale (YFAS), the Night Eating Questionnaire (NEQ), and Beck Depression Inventory (BDI). Of the students, 15.2% had food addiction, 8.3% had night-eating syndrome, and 36.2% had moderate depression. Frequency of food addiction and night-eating syndrome were higher in those with moderate to severe depression and night-eating syndrome was higher in those with food addiction (p < 0.001). A positive correlation was found between mean YFAS, NEQ, and BDI scores in the general population and both genders (p < 0.001). Furthermore, BMI levels, having received psychological treatment, waking up and eating at night, and depression level increased the likelihood of food addiction, while waking up and eating at night, and depression levels increased the likelihood of night-eating syndrome. The findings of the study made a significant contribution to the literature in understanding food addiction, night eating, depression levels and their relationship with each other in university students. Multi-center studies in which the effects of these three factors are examined together should be conducted on different student populations. Students should be given training on healthy nutrition and mental health protection, and their awareness should be raised.

Smoking may increase the usage of antidepressant: evidence from genomic perspective analysis

This study uses the two-sample Mendelian randomization (TSMR) method to explore the causal relationships between smoking initiation (SMKI), never smoking (NSMK), past tobacco smoking (PTSMK), and the usage of antidepressants (ATD). Single-nucleotide polymorphisms (SNPs) with genome-wide significance (P < 5E-08) related to SMKI, NSMK, and PTSMK were selected from the genome-wide association study (GWAS) database as instrumental variables (IVs). The main method, inverse variance weighted (IVW), was utilized to investigate the causal relationship. The results demonstrated a positive causal relationship between SMKI and ATD use, where SMKI leads to an increase in ATD use. Conversely, NSMK and PTSMK showed a negative causal relationship with ATD use, meaning that NSMK and PTSMK lead to a reduction in ATD use. Additionally, sensitivity analysis showed that the results of this study were robust and reliable. Using the TSMR method and from a genetic perspective, this study found that SMKI leads to an increase in ATD use, while NSMK and PTSMK reduce ATD use.

Causal associations between dietary factors with head and neck cancer: A two-sample Mendelian randomization study

Objective

Although an association exists between dietary habits and head and neck cancer (HNC), the direct cause-and-effect connection remains elusive. Our objective was to investigate the causal associations between dietary factors and the likelihood of developing HNC.

Methods

Genome-wide association study (GWAS) summary statistics for dietary habits were screened from the UK Biobank, the OncoArray Oral Cavity and Oropharyngeal Cancer consortium, and the FinnGen biobank for HNC. A two-sample Mendelian randomization (MR) analysis was utilized to establish causality. The primary method of analysis was inverse variance weighting (IVW).

Results

Clear evidence of an inverse association existed between dried fruit intake and HNC in both cohorts (OncoArray consortium: IVW OR = 0.183; 95% CI, 0.037-0.915; p = .03864; FinnGen: IVW OR = 0.281; 95% CI, 0.115-0.688; p = .00547). In addition, fresh fruit (IVW-mre OR = 0.066; 95% CI, 0.011-0.413; p = .00369), beef (IVW OR = 15.094; 95% CI, 1.950-116.853; p = .00934), and lamb/mutton intakes (IVW OR = 5.799; 95% CI, 1.044-32.200; p = .0448) were significantly associated with HNC in the OncoArray consortium cohort.

Conclusions

Dried fruit intake may be a protective factor against HNC. The association of fresh fruit and red meat intakes with HNC warrants careful interpretation. Additional studies are necessary to explore potential mechanisms for further evidence.Level of evidence: III.

Retrospective evaluation of novel serum inflammatory biomarkers in first-episode psychiatric disorders: diagnostic potential and immune dysregulation

Background

This study assessed the diagnostic capabilities of eight inflammatory biomarkers in first-episode schizophrenia (SCZ), bipolar disorder (BD), and depression (D), examining their differential expression across these psychiatric disorders. The markers studied include neutrophils/lymphocyte ratio (NLR), aggregate index of systemic inflammation (AISI), systemic immune-inflammation index (SII), systemic inflammation response index (SIRI), lymphocytes/high-density lipoprotein (HDL) ratio (LHR), monocytes/HDL ratio (MHR), neutrophils/HDL ratio (NHR), and platelets/HDL ratio (PHR).

Methods

We conducted a retrospective observational study involving 335 individuals with SCZ, 68 with BD, 202 with D, and 282 healthy controls (C) to evaluate hematologic parameters from untreated patients and controls.

Results

Significant differences in biomarker levels were found between patient groups and controls. Logistic regression analysis indicated that NHR and MHR (p < 0.001), as well as LHR and NLR (p < 0.01), were predictive factors for SCZ. MHR was a predictive factor for BD (p < 0.05). NHR (p < 0.01) and MHR (p < 0.001) were predictive factors for distinguishing between D and C. The area under the curve (AUC) value of the NHR + MHR + NLR composite index model for the SCZ group was 0.846 (p < 0.001). In the BD group, the AUC value for the MHR was 0.816 (p < 0.001). The D group's combined AUC value of NHR + MHR was 0.824 (p < 0.001).

Conclusion

This study highlights the diagnostic value of inflammatory biomarkers in distinguishing SCZ, BD, and D based on their differential expression.

The causal effects of dietary component intake and blood metabolites on risk of delirium: a Mendelian randomization study

Backgrounds

Growing evidence has indicated that the nutritional quality of dietary intake and alterations in blood metabolites were related to human brain activity. This study aims to investigate the causal relationship between dietary component intake, blood metabolites, and delirium risks.

Methods

We performed Mendelian randomization (MR) analysis using genetic variants as instrumental variables for dietary component intake, blood metabolites, and delirium. Inverse variance weighting, maximum likelihood, weighted median, weighted mode, and MR-Egger methods were used for statistical analyses.

Results

We found that genetic prediction of salt added to food (odds ratio [OR] 1.715, 95% confidence interval [CI] 1.239-2.374, p = 0.001) significantly increased the risks of delirium, while low-fat polyunsaturated margarine used in cooking (OR 0.044, 95%CI 0.004-0.432, p = 0.007), cheese intake (OR 0.691, 95%CI 0.500-0.955, p = 0.025) and coffee intake (OR 0.595, 95%CI 0.370-0.956, p = 0.032) was suggestively associated with decreased risks of delirium. Moreover, increased blood 1-stearoylglycerol levels (OR 0.187, 95%CI 0.080-0.435, p = 9.97E-05) significantly contributed to reducing the risks of delirium. 3-methoxytyrosine (OR 0.359, 95%CI 0.154-0.841, p = 0.018) also has the potential to decrease the risk of delirium.

Conclusion

Our study highlights the potential causal effect relationships of dietary component intake and blood metabolites on the risk of delirium, which potentially provides novel insights into targeted dietary prevention strategies or biomarkers for delirium.

Association between air pollutants and four major mental disorders: Evidence from a Mendelian randomization study

BACKGROUND

Existing epidemiological studies have indicated a correlation between air pollutants and the occurrence of mental disorders. However, it is difficult to estimate the causal relationship between the two because of the limitations of traditional epidemiological research. In our study, we aimed to extensively explore the causal relationship between five types of air pollutants and four types of mental disorders.

METHODS

Based on the IEU OPEN GWAS database, we performed a two-sample MR analysis. The primary analysis method utilized was the inverse variance weighted (IVW) method, supplemented by the MR-Egger method and the weighted median method. Additionally, we conducted sensitivity analyses with the Cochran's Q statistic method, the leave-one-out method, and the MR-Egger intercept. We chose at least 4 GWAS datasets for each of the four psychiatric diseases and conducted a meta-analysis of our results of the MR analysis.

RESULTS

The meta-analysis's findings demonstrated a causal link between depression and PM2.5 (OR=1.020, 95 %CI: (1.010,1.030), P=0.001). PM10 and schizophrenia are also causally related (OR=1.136, 95 %CI: (1.034,1.248), P=0.008). Nitrogen oxides and bipolar disorder have a causal relationship (OR=1.002, 95 %CI: (1.000,1.003), P=0.022). Nitrogen oxides and schizophrenia have a high causal association (OR=1.439, 95 %CI: (1.183,1.752), P<0.001).

CONCLUSION

This study observed a causal association between increased concentrations of PM2.5, PM10, and nitrogen oxides and the occurrence of depression, schizophrenia, and bipolar disorder. Our research findings have certain guiding implications for treating and preventing mental disorders.

Association between weekend catch-up sleep and depression of the United States population from 2017 to 2018: A cross-sectional study

Insufficient sleep on weekdays has become a societal norm, and studies have shown that sleep deprivation increases the risk of depression. Although individuals often resort to weekend catch-up sleep (CUS) as a compensatory measure, the present evidence supporting its efficacy in mitigating the risk of depression is limited. This article attempts to explore the relationship between CUS and depression. In this study, a total of 5510 participants were included, characterized into two groups: nondepressed (n = 5051) and depressed (n = 459), with data extracted from the National Health and Nutrition Examination Survey (NHANES). Compared with people without CUS, those practicing CUS exhibited a significantly lower risk of depression (OR = 0.81, P = 0.048). In subgroup analysis, this reduction effect was only observed in males (OR = 0.70, 95 % CI 0.05 to 0.99, P = 0.04), middle-aged (>40, ≤60) (OR: 0.57, 95 % CI: 0.40 to 0.81, P = 0.002), married or living with parents (OR: 0.61, 95 % CI: 0.44 to 0.86, P = 0.004), groups with three or more family members (OR: 0.69, 95 % CI: 0.52 to 0.93, P = 0.01), and individuals without alcohol intake (OR: 0.24,95 % CI: 0.09 to 0.67, P = 0.006). Therefore, in the realm of depression treatment, doctors may consider advising patients to get adequate sleep on weekends as part of their overall treatment plan. At the same time, individuals can also choose weekend sleep as a proactive strategy for regulating their psychological status.

Causal effects of dietary composition on multiple sclerosis risk and severity: a Mendelian randomization study

Objectives

Observational studies have found potential associations between dietary intake and multiple sclerosis (MS). However, these associations are inconsistent, and the causal relationship remains unclear. In this study, we aim to examine the causal relationship between genetically predicted dietary composition and the risk and severity of MS using two-sample Mendelian randomization.

Method

Genetic instruments for 30 different dietary compositions were extracted from large-scale genome-wide association studies (GWAS), mainly from the UK Biobank dataset. The GWAS data for MS risk and severity were obtained from the International Multiple Sclerosis Genetics Consortium. The primary analysis employed either the inverse variance weighted method or the Wald ratio method to evaluate the causal association. Several sensitivity analyses were also performed.

Results

Genetically predicted higher pork intake was causally associated with an increased risk of MS (odds ratio [OR] = 6.76; p = 0.005), while genetically driven higher cereal intake (OR = 0.43, p = 0.016), vitamin C supplement (OR < 0.01; p = 4.34 × 10-5), folic acid supplement (OR < 0.01; p = 4.91 × 10-71), and fish oil supplement (OR = 0.04; p = 0.017) were causally linked to a decreased risk of MS. In addition, genetically predicted higher alcoholic intake (OR = 1.17; p = 0.041) was causally associated with an increase in MS severity, while folic acid supplement (OR < 0.01; p = 0.015) was causally linked to a decrease in MS severity.

Interpretation

This study found that increased consumption of cereal, vitamin C, folic acid, and fish oil, coupled with reduced pork and alcohol intake, may potentially decrease the risk and severity of MS. These findings inform the development of dietary-based strategies for MS prevention and treatment.

Associations between dietary habits and bipolar disorder: a diet-wide mendelian randomization study

Background

Diet/nutrition is critically important in the pathogenesis, progression, and treatment outcomes of various mental disorders. Current research predominantly focuses on the role of diet in the development and treatment of depression, with less attention given to the relationship between diet and Bipolar Disorder (BD).

Method

We employed Mendelian Randomization (MR) to investigate the relationship between 28 dietary habits and BD. An analysis was conducted using publicly available genome-wide association study data from the UK Biobank dataset. Various dietary habits were analyzed as exposures with BD as the outcome, mainly using the Inverse Variance Weighted (IVW) method.

Results

Intake of non-oily fish and sponge pudding both have a positive association with BD. Oily fish, dried fruit, apples, salt, and cooked vegetables intake also appeared potentially risky for BD, although the possibility of false positives cannot be ruled out. Sensitivity analysis further confirmed the robustness of these findings.

Conclusion

Our research provides evidence of a relationship between various dietary habits and BD. It underscores the need for careful dietary management and balance to reduce the risk of BD, suggesting caution with dietary preferences for fish and sponge pudding. Furthermore, more detailed studies are needed to further understand the potential impacts of high-sugar and high-protein diets on BD development.

Dietary factors and Alzheimer's disease risk: a Mendelian randomization study

BACKGROUND

Prior observational research has investigated the association between dietary patterns and Alzheimer's disease (AD) risk. Nevertheless, due to constraints in past observational studies, establishing a causal link between dietary habits and AD remains challenging.

METHODS

Methodology involved the utilization of extensive cohorts sourced from publicly accessible genome-wide association study (GWAS) datasets of European descent for conducting Mendelian randomization (MR) analyses. The principal analytical technique utilized was the inverse-variance weighted (IVW) method.

RESULTS

The MR analysis conducted in this study found no statistically significant causal association between 20 dietary habits and the risk of AD (All p > 0.05). These results were consistent across various MR methods employed, including MR-Egger, weighted median, simple mode, and weighted mode approaches. Moreover, there was no evidence of horizontal pleiotropy detected (All p > 0.05).

CONCLUSION

In this MR analysis, our finding did not provide evidence to support the causal genetic relationships between dietary habits and AD risk.

Causal associations between dietary factors and colorectal cancer risk: a Mendelian randomization study

Background

Previous epidemiological studies have found a link between colorectal cancer (CRC) and human dietary habits. However, the inherent limitations and inevitable confounding factors of the observational studies may lead to the inaccurate and doubtful results. The causality of dietary factors to CRC remains elusive.

Methods

We conducted two-sample Mendelian randomization (MR) analyses utilizing the data sets from the IEU Open GWAS project. The exposure datasets included alcoholic drinks per week, processed meat intake, beef intake, poultry intake, oily fish intake, non-oily fish intake, lamb/mutton intake, pork intake, cheese intake, bread intake, tea intake, coffee intake, cooked vegetable intake, cereal intake, fresh fruit intake, salad/raw vegetable intake, and dried fruit intake. In our MR analyses, the inverse variance weighted (IVW) method was employed as the primary analytical approach. The weighted median, MR-Egger, weighted mode, and simple mode were also applied to quality control. Heterogeneity and pleiotropic analyses were implemented to replenish the accuracy of the results.

Results

MR consequences revealed that alcoholic drinks per week [odds ratio (OR): 1.565, 95% confidence interval (CI): 1.068-2.293, p = 0.022], non-oily fish intake (OR: 0.286; 95% CI: 0.095-0.860; p = 0.026), fresh fruit intake (OR: 0.513; 95% CI: 0.273-0.964; p = 0.038), cereal intake (OR: 0.435; 95% CI: 0.253-0.476; p = 0.003) and dried fruit intake (OR: 0.522; 95% CI: 0.311-0.875; p = 0.014) was causally correlated with the risk of CRC. No other significant relationships were obtained. The sensitivity analyses proposed the absence of heterogeneity or pleiotropy, demonstrating the reliability of the MR results.

Conclusion

This study indicated that alcoholic drinks were associated with an increased risk of CRC, while non-oily fish intake, fresh fruit intake, cereal intake, and dried fruit were associated with a decreased risk of CRC. This study also indicated that other dietary factors included in this research were not associated with CRC. The current study is the first to establish the link between comprehensive diet-related factors and CRC at the genetic level, offering novel clues for interpreting the genetic etiology of CRC and replenishing new perspectives for the clinical practice of gastrointestinal disease prevention.

Causal relationship between diabetes and depression: A bidirectional Mendelian randomization study

OBJECTIVE

This study explores the causal relationship between diabetes and depression using a two-sample Mendelian Randomization (TSMR) method.

METHODS

The study selected single nucleotide polymorphisms (SNPs) closely associated with diabetes and depression in European populations from the Genome-Wide Association Study (GWAS) database, to serve as instrumental variables (IVs). The main evaluation method was inverse variance weighted analysis (IVW), supplemented by verification using Weighted median, Weighted mode, and MR Egger methods. The Odds Ratio (OR) and 95 % Confidence Interval (CI) were used as the main evaluation indicators, along with sensitivity analysis.

RESULTS

This study found a negative correlation between diabetes and depression, suggesting that diabetes may reduce the risk of depression [IVW(FE): OR: 0.901, 95 % CI: 0.823 to 0.987; P = 0.025 < 0.05]. This finding was further confirmed by the Weighted median [OR: 0.844, 95 % CI: 0.730 to 0.974; P = 0.021 < 0.05] and Weighted mode method [OR: 0.766, 95 % CI: 0.637 to 0.921; P = 0.006 < 0.05]. However, the reverse showed no causal relationship between depression and diabetes (P > 0.05). Sensitivity analysis found no pleiotropy, and there were no large influences from individual SNPs on the result's robustness; the results are stable and reliable.

CONCLUSION

For the first time, this study using TSMR analysis found a negative correlation between diabetes and the risk of depression onset in European populations, suggesting that diabetes might reduce the risk of depression. But as the mechanisms are still unclear, these findings warrant further study.