Green tea and coffee consumption is inversely associated with depressive symptoms in a Japanese working population

Risk and protective factors for severe mental disorders in Asia

Among 369 diseases and injuries, the years lived with disability (YLDs) and disability-adjusted life-years (DALYs) rates for severe mental illnesses (SMIs) are within the top 20 %. Research on risk and protective factors for SMIs is critically important, as acting on modifiable factors may reduce their incidence or postpone their onset, while early detection of new cases enables prompt treatment and improves prognosis. However, as most of the studies on these factors are from Western countries, the findings are not generalizable across ethnic groups. This led us to conduct a systematic review of the risk and protective factors for SMIs identified in Asian studies. There were common factors in Asian and Western studies and unique factors in Asian studies. In-depth knowledge of these factors could help reduce disability, and the economic and emotional burden of SMIs. We hope that this review will inform future research and policy-making on mental health in Asian countries.

The effects of tea polyphenols on emotional homeostasis: Understanding dementia risk through stress, mood, attention & sleep

Decades of research provide evidence that certain phytochemicals in tea (Camellia sinensis) and other herbal beverages are protective against the development of sporadic types of dementia in later life. Since tea drinking is an economical and widely adopted social-cultural practice across all age groups, it is an ideal product to target in designing low-cost dietary interventions for Alzheimer's Disease (AD), the most prevalent form of dementia. In this review, we focus on the protective roles of tea-derived polyphenols and other phytochemicals on mood, the stress response, attention, and sleep, in keeping with the perspective that many early neuropathological events in AD may stem, in part, from allostatic overload. This approach aligns with the perspective that many forms of dementia, including AD, begin to take root in the brain decades prior to symptom onset, underscoring the need for early uptake of accessible and viable lifestyle interventions. The findings reviewed here suggest that consuming green and oolong tea can improve mood and reduce overall stress. However, given the caffeine content in tea and its association with stress reactivity, the effects of daily whole tea consumption on the emotional state are likely dose-dependent with an inverted-U relationship to wellbeing. Plant-based beverages that are to be consumed in high daily quantities for health purposes and which are naturally free of caffeine, such as Rooibos, may be more appropriate as a dietary supplement for managing emotional regulation over the lifetime.

Association between dietary caffeine, coffee, and tea consumption and depressive symptoms in adults: A systematic review and dose-response meta-analysis of observational studies

Background

Recent studies have reported an association between dietary caffeine intake (coffee and tea) and the presence of depressive symptoms. However, the findings are not conclusive.

Purpose

This study aimed to examine the correlation between the consumption of dietary caffeine (coffee and tea) and the presence of depressive symptoms in adults.

Methods

PubMed and Scopus databases were searched until December 2021. Two investigators analyzed data from identified studies and rated the quality of the evidence using the GRADE approach. Using the random-effects models, we estimated the relative risks (RRs) and 95% confidence intervals (CIs). We also modeled the dose-response associations through a one-stage, weighted mixed-effects meta-analysis.

Results

A total of 29 eligible studies included a total of 422,586 participants. On comparing the highest with the lowest category in cohort studies, we identified an inverse association between the intake of coffee and depressive symptoms (RR: 0.89, 95%CI: 0.82-0.95; I² = 63.7%, GRADE = low). There was a 4% reduction in the risk of depression associated with an increase in coffee intake of 240 ml/day (RR: 0.96, 95%CI: 0.95, 0.98; I² = 22.7%). By comparing the highest category with the lowest category in cohort studies, we discovered that caffeine intake was inversely associated with depressive symptoms (RR: 0.86, 95%CI: 0.79, 0.93; I² = 0.0%, GRADE = moderate). Based on our data analysis, no correlation exists between tea consumption and depressive symptoms.

Conclusion

According to our findings, coffee and dietary caffeine may have a protective effect against the development of depression. However, no evidence suggesting a link between tea consumption and reduced depressive symptoms has been found. Therefore, further longitudinal studies are needed to substantiate the causal relationship between coffee, tea, and caffeine and the risk of depression.

Green tea consumption and risk of depressive symptoms: Results from the TCLSIH Cohort Study

BACKGROUND

The prospective studies on the effect of particular type of tea consumption, especially green tea, on depressive symptoms are limited.

OBJECTIVE

The aim of this study is to investigate the prospective association between green tea consumption and depressive symptoms in a large general adult population.

METHODS

This prospective cohort study investigated 7524 participants aged 25 to 90 years from May 2013 to December 2018 and they were free of cardiovascular disease, cancer, and depressive symptoms at baseline. Green tea consumption was obtained through a validated food frequency questionnaire. Depressive symptoms were assessed by using the Self-Rating Depressive Scale (SDS). The association between green tea consumption and depressive symptoms was analyzed by Cox proportional hazards regression models.

RESULTS

A total of 1064 first incident cases of depressive symptoms (SDS ≥45) occurred during 14,661 person-years of follow-up (median follow-up of 2.0 years). In the crude model, the hazard ratios (95% confidence intervals) were 1.00 (reference), 0.95 (0.81, 1.12), 0.97 (0.83, 1.14) and 0.95 (0.79, 1.14), respectively. After adjusting for demographic characteristics, lifestyle factors, and dietary intake, the multivariable adjusted hazard ratios (95% confidence intervals) were 1.00 (reference), 0.88 (0.74, 1.05), 0.84 (0.69, 1.02) and 0.78 (0.63, 0.97), respectively.

CONCLUSIONS

The prospective study suggests that frequent green tea consumption is associated with a decreased risk of depressive symptoms in the general Chinese population.

Green Tea Consumption and Risk of Depression Symptoms: A Systematic Review and Meta-Analysis of Observational Studies

This systematic review and meta-analysis aimed to investigate the association between green tea consumption and depression symptom risk, using subgroup analyses concerning study design, geographical region of study, adjustment factors, age, cut-off for the highest consumption category, and depression assessment methods applied. We used PubMed to search for relevant literature. The inclusion criteria were studies that (a) investigated this association as a primary or secondary outcome; (b) published in English; (c) assessed and reported hazard ratios or odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) for depression symptoms, or included sufficient information to allow their calculation; (d) included at least two groups differentiated based on green tea consumption (e.g., high and low); (e) reported the prevalence of depression symptoms in each group; and (f) reported the sample size for each group. Eight articles were found to meet all criteria. The results indicated that high green tea consumption is inversely associated with depression symptoms. The pooled OR was 0.66 (95% CI 0.58-0.74), and significant heterogeneity was not observed. Subgroup analysis showed that study design impacted results (cohort study [one study]: OR=0.29, 95% CI=0.04-2.14; cross-sectional study [seven studies]: OR=0.66, 95% CI=0.59-0.75). These findings suggest that green tea consumption reduces the risk of depression symptoms. This association was also observed in the cohort study included, but the results in which did not reach the significant level. Therefore, further cohort studies are needed to confirm the potential causal relationship in this regard.

Higher dietary phytochemical index is associated with lower odds of knee osteoarthritis

Previous studies have shown that adherence to dietary patterns rich in plant-based foods may reduce the odds of osteoarthritis; however, limited data are available on the association of consumption of diets rich in phytochemicals and odds of knee osteoarthritis (KOA). In this case–control study conducted in Iran, we aimed to investigate whether a higher dietary phytochemical index (DPI) is associated with decreased odds of having KOA. A total of 124 cases aged 20–60 years diagnosed with bilateral primary KOA according to the American College of Rheumatology criteria and 124 controls frequency-matched on age, sex, and body mass index (BMI) were included in the study. A validated food frequency questionnaire (FFQ) was used to collect information on dietary intakes. To calculate DPI scores, the dietary energy derived from foods rich in phytochemicals (kcal) was divided by the participant’s total daily energy intake (kcal). Patients with KOA had lower intakes of dietary fiber (P = 0.004), vitamin A (P = 0.007), vitamin C (P = 0.001), and folate (P = 0.021) compared to controls. In the crude model, individuals in the third tertile of DPI had 65% lower odds of having KOA compared to those in the first tertile (OR 0.35, 95% CI 0.19 to 0.67, P-trend = 0.001). After adjustment for potential confounders, including age, sex, physical activity, smoking, and supplement use, this inverse association remained significant (OR 0.37, 95% CI 0.19 to 0.73, P-trend = 0.004). After further adjustment for BMI, this inverse association between DPI and odds of KOA also remained significant (OR 0.35, 95% CI 0.18 to 0.69, P-trend = 0.003). These findings suggest that adherence to a phytochemical-rich diet, as indicated by the increasing DPI score, is associated with lower odds of KOA.

The associations between sleep behaviors, lifestyle factors, genetic risk and mental disorders: A cohort study of 402 290 UK Biobank participants

BACKGROUND

Sleep behaviors were believed to be associated with mental disorders (MD). However, the underlying mechanism of such association relationship, especially the role of multiple lifestyle factors in it remains unclear.

METHODS

A total of 402,290 participants from UK Biobank who don't have MD at baseline were included. They were divided into poor, intermediate and healthy sleep patterns according to the sleep score, which was calculated based on the data collecting from five sleep behaviors. Cox proportional hazard model was used to estimate the associations between sleep behaviors and MD. The associations were further estimated when taking lifestyle factors such as physical activity, coffee intake, tea intake and genetic susceptibility into account.

RESULTS

Healthy sleep pattern was associated with lower risk of overall MD status (HR,0.41, 95%CI,0.39-0.43), depressive disorders (HR,0.34, 95%CI,0.31-0.37) and anxiety disorders (HR,0.46, 95%CI,0.41-0.79), compared with poor sleep pattern. And in each subgroup of physical activity, tea intake, coffee intake, age and genetic risk scores (GRS), healthy sleep pattern could partly offset the risk of diseases.

CONCLUSIONS

Our study suggested healthy sleep behaviors could diminish the negative effect from genetic predisposition and lifestyle factors on the risk of MD, highlighting the benefit of healthy sleep pattern.

Potential Application of Tea Polyphenols to the Prevention of COVID-19 Infection: Based on the Gut-Lung Axis

Coronavirus disease 2019 (COVID-19) disrupts the intestinal micro-ecological balance, and patients often develop the intestinal disease. The gut is the largest immune organ in the human body; intestinal microbes can affect the immune function of the lungs through the gut-lung axis. It has been reported that tea polyphenols (TPs) have antiviral and prebiotic activity. In this review, we discussed TPs reduced lung-related diseases through gut-lung axis by inhibiting dysbiosis. In addition, we also highlighted the preventive and therapeutic effects of TPs on COVID-19 complications, further demonstrating the importance of research on TPs for the prevention and treatment of COVID-19 in humans. Based on this understanding, we recommend using TPs to regulate the gut microbiota to prevent or alleviate COVID-19 through the gut-lung axis.

Anti-Depressant Properties of Crocin Molecules in Saffron

Saffron is a valued herb, obtained from the stigmas of the C. sativus Linn (Iridaceae), with therapeutic effects. It has been described in pharmacopoeias to be variously acting, including as an anti-depressant, anti-carcinogen, and stimulant agent. The therapeutic effects of saffron are harbored in its bioactive molecules, notably crocins, the subject of this paper. Crocins have been demonstrated to act as a monoamine oxidase type A and B inhibitor. Furthermore, saffron petal extracts have experimentally been shown to impact contractile response in electrical field stimulation. Other research suggests that saffron also inhibits the reuptake of monoamines, exhibits N-methyl-d-aspartate antagonism, and improves brain-derived neurotrophic factor signaling. A host of experimental studies found saffron/crocin to be similarly effective as fluoxetine and imipramine in the treatment of depression disorders. Saffron and crocins propose a natural solution to combat depressive disorders. However, some hurdles, such as stability and delivery, need to be overcome.

Coffee and caffeine intake in relation to symptoms of psychological disorders among adults

OBJECTIVE

Given that there is an inconsistency in the findings related to the relationship between coffee and caffeine consumption and symptoms of psychological disorders, we performed a cross-sectional analysis to examine the association between coffee and caffeine intake and symptoms of psychological disorders among adults.

DESIGN

In this cross-sectional study, 3362 participants were included. We assessed the coffee and caffeine intakes using a self-completed food frequency questionnaire (FFQ). Symptoms of depression, anxiety, and psychological distress were assessed using HADS and GHQ screening tools.

RESULTS

The mean age of participants in this study was 36.2±7.8 years. After controlling for potential confounders, individuals who consumed coffee weekly or more had a significantly lower odds of symptoms of depression (OR: 0.67; 95% CI: 0.46-0.96) and symptoms of anxiety (OR: 0.57; 95% CI: 0.34-0.95) compared with those who did not consume coffee. However, no significant association was found between coffee intake and symptoms of psychological distress (OR: 0.98; 95%CI: 0.68-1.42). No significant relationship was found between caffeine intake and odds of symptoms of depression (OR: 0.94; 95% CI: 0.75-1.16), symptoms of anxiety (OR: 0.90; 95% CI: 0.67-1.20), and symptoms of psychological distress (OR: 1.13; 95% CI: 0.89-1.42).

CONCLUSION

Compared with lack of coffee intake, weekly or more coffee consumption might be correlated with symptoms of depression and anxiety.

Green Tea Consumption and Depressive Symptoms among Japanese Workers: The Furukawa Nutrition and Health Study

Although several cross-sectional studies have described an inverse association between green tea consumption and depressive symptoms, only one study has prospectively investigated this association. We investigated the cross-sectional and prospective associations between green tea consumption and depressive symptoms in a working population in Japan. Participants were 1987 workers who participated in the baseline survey for a cross-sectional association, and 916 participants who did not have depressive symptoms at baseline who responded to both the baseline and follow-up surveys for a prospective association. Green tea consumption was evaluated with a validated self-administered diet history questionnaire. Depression symptoms were evaluated with the Center for Epidemiologic Studies Depression (CES-D) scale. Multiple logistic regression was conducted to estimate the odds ratio of depressive symptoms based on green tea consumption. In the cross-sectional analysis, green tea consumption was not associated with the prevalence of depression symptoms. Moreover, consumption at baseline was not associated with depression symptoms after 3 years; the multivariable-adjusted odds ratio of depressive symptoms for ≥2 cups/day of green tea was 1.12 (95% confidence interval 0.65–1.91) compared with <4 cups/week after adjustment for covariates including dietary factors (trend p = 0.67). Our results suggest that there is no association of consumption of green tea with symptoms of depression in Japanese.

The Association between Habitual Green Tea Consumption and Comprehensive Frailty as Assessed by Kihon Checklist Indexes among an Older Japanese Population

Background: It is unclear whether habitual green tea consumption is related to comprehensive frailty. Objectives: We conducted this study to investigate this relationship among an elderly Japanese population. Methods: This was a cross-sectional study of baseline data from 2012. The study included 5668 Japanese participants (2766 men and 2902 women aged 65 years or older). The subjects completed a validated self-administered food frequency questionnaire that included questions on their green tea consumption. We evaluated comprehensive frailty using a 25-item Kihon Checklist (KCL), which comprised seven domains (instrumental activities of daily living (IADL), physical function, malnutrition, oral or eating function, socialization and housebound, cognitive function, and depression). Frailty was defined as a KCL score greater than or equal to seven. Results: We found that a higher consumption of green tea was associated with a lower prevalence of comprehensive frailty in both sexes. Further age-stratified analysis showed that a higher consumption of green tea among women was associated with a lower prevalence of comprehensive frailty, regardless of age. In men, however, this association was found only in the older age groups. An analysis of the association between green tea consumption and the frailty subdomains showed that green tea consumption was associated with a lower prevalence of oral dysfunction and cognitive problems in both sexes. In addition, only in women was higher green tea consumption found to be associated with a lower prevalence of IADL and mobility-related disability problems. Conclusions: Green tea consumption is inversely associated with the prevalence of comprehensive frailty in Japanese men and women. Longitudinal studies are required to confirm this association.

The relationship of caffeinated beverages with depressive symptoms and decision-making

BACKGROUND: Caffeine can affect depressive symptoms and decision-making. OBJECTIVE: This study aims to examine the relationship between caffeinated beverages consumption with depressive symptoms and decision-making styles. METHODS: This cross-sectional study was conducted with 432 adults working in office environment. The questionnaire consisting of individuals’ socio-demographic attributes, the frequency and the amount of caffeinated beverages consumption, the “Epidemiological Research Center-Depression (CES-D) Scale” and the “Decision-Making Styles Scale” were used. The frequency and amount of caffeinated beverages were determined using the food frequency questionnaire (FFQ). The participants were asked to choose which cup/mug they prefer to drink their caffeinated beverages and what amount they consume that beverage at a time. All the data were collected using online platforms. RESULTS: In the study, 76.7%of the participants were female and the mean age was 31.5±8.0 years. The average daily total caffeine intake of the participants was 425.8±461.4 mg and the total CES-D scale score was 17.7±11.2 points. It was found that as the amount of caffeine consumed increased, intuitive decision-making decreased and depressive symptoms increased (p <  0.05). In linear regression analysis, total caffeine consumption was found to be a significant predictor for the intuitive decision-making score (B: –0.151; p:0.002). When caffeine consumption is controlled, intuitive and rational decision making decreases with increasing depressive symptoms while addiction and avoidance decision making increased (p <  0.05). CONCLUSIONS: As a result, the amount of caffeine consumed daily was related to intuitive decision-making but did not effect depression. It has been observed that depressive symptoms affect decision-making styles in different ways. To our knowledge, our study is the first to examine the effects of caffeine consumption on depression and decision-making styles. Accordingly, future studies may focus on the link between caffeine consumption, depression, and decision-making styles in larger populations and the mechanisms that influence this relationship.

Effects of black tea consumption and caffeine intake on depression risk in black tea consumers

BACKGROUND

The aim of this study was to compare black tea consumption and caffeine intake with depression status.

SUBJECTS AND METHODS

This study was conducted on 491 adults (M:169, F:322). The average daily caffeine intake of individuals was calculated using the amounts of caffeinated beverages they consumed daily and the caffeine contents of these beverages. The participants' depression status was determined using the Beck Depression Inventory (BDI). All of the research data were evaluated using STATA.

RESULTS

According to BDI scores, 30.1% of participants had depression. Black tea was consumed by all of the participants and also had the highest consumption level of 620.1±90.4mL and the mean caffeine intake of the participants was 629.5±418.8 mg. Multivariate regression analyses showed that consuming more than 1 cup was protective against depression up to 4 cups. Moreover, a 450-600 mg caffeine intake also reduces the risk of depression than lower or higher intake levels.

CONCLUSION

Our study suggests that black tea consumption up to 4 cups and caffeine intake between 450-600 mg can help protect against depression. Further studies are needed to better understand the protective effects of black tea and caffeine on depression.

Type of tea consumption and depressive symptoms in Chinese older adults

Background

Existing research indicates that tea drinking may exert beneficiary effects on mental health. However, associations between different types of tea intake and mental health such as depression have not been fully examined. The purpose of this study was to examine the associations of green tea, fermented tea, and floral tea consumption with depressive symptoms.

Methods

We used data from the 2018 wave of the Chinese Longitudinal Healthy Longevity Survey, a nationwide survey on older adults in mainland China. A total of 13,115 participants (mean age 83.7 years, 54.2% were women) with valid responses were included in the analysis. The type (green, fermented [black, Oolong, white, yellow, dark, and compressed teas], and floral) and the frequency of tea consumption were recorded, and depressive symptoms were assessed using 10-item of the Center for Epidemiologic Studies Depression Scale (CES-D-10). We examined the associations between the type and the frequency of tea intake and depression, controlling for a set of demographic, socioeconomic, psychosocial, behavioral, and health-related variables.

Results

Overall, intakes of green tea, fermented tea, and floral tea were all significantly associated with lower prevalence of depressive symptoms, independent of other risk factors. Compared with the group of no tea intake, the adjusted ORs of depressive symptoms for daily green tea, fermented tea, and floral tea intake were 0.85 (95% CI: 0.76–0.95), 0.87 (95% CI: 0.76–0.99), and 0.70 (95% CI: 0.59–0.82), respectively. Linear associations were observed between the frequencies of all three types of tea intake and depressive symptoms (P < 0.05 for trends for all three types). The associations of the type and the frequency of tea intake and depressive symptoms were robust in several sensitivity analyses.

Conclusions

Among Chinese older adults, regularly consumed any type of tea (green, fermented, or floral) were less likely to show depressive symptoms, the associations seemed more pronounced among floral tea and green tea drinkers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02203-z.

Beneficial Effects of Green Tea Catechins on Female Reproductive Disorders: A Review

Tea is one of the most widely consumed beverages worldwide after water, and green tea accounts for 20% of the total tea consumption. The health benefits of green tea are attributed to its natural antioxidants, namely, catechins, which are phenolic compounds with diverse beneficial effects on human health. The beneficial effects of green tea and its major bioactive component, (-)-epigallocatechin-3-gallate (EGCG), on health include high antioxidative, osteoprotective, neuroprotective, anti-cancer, anti-hyperlipidemia and anti-diabetic effects. However, the review of green tea's benefits on female reproductive disorders, including polycystic ovary syndrome (PCOS), endometriosis and dysmenorrhea, remains scarce. Thus, this review summarises current knowledge on the beneficial effects of green tea catechins on selected female reproductive disorders. Green tea or its derivative, EGCG, improves endometriosis mainly through anti-angiogenic, anti-fibrotic, anti-proliferative and proapoptotic mechanisms. Moreover, green tea enhances ovulation and reduces cyst formation in PCOS while improving generalised hyperalgesia, and reduces plasma corticosterone levels and uterine contractility in dysmenorrhea. However, information on clinical trials is inadequate for translating excellent findings on green tea benefits in animal endometriosis models. Thus, future clinical intervention studies are needed to provide clear evidence of the green tea benefits with regard to these diseases.

Caffeine Intake and Mental Health in College Students

Background The effect of caffeine on the human body, both short-term and long-term, has been studied in great depth, particularly its association with psychiatric disorders. This study aims to investigate whether there is a correlation between caffeine intake and anxiety and depression among college students. Methodology A survey was administered to college students at Florida State University. Data regarding participant characteristics and caffeine intake were collected. Generalized Anxiety Disorder-7 and Patient Health Questionnaire-9 scores were used to assess symptoms of anxiety and depression, respectively. Results A total of 114 participants were included in the survey, consisting mainly of women (94 [82.5%]) and junior-level students (37 [32.5%]). The main source of caffeine was coffee (64.0%), and the main reasons for caffeine intake were pleasure (43.9%) and to study outside of class (29.8%); however, no association was found between sex or grade point average and number of cups of caffeine consumed. Upper levels of education (super senior or fifth-year students), depressive symptoms (poor appetite, overeating, sleep disorders, depressed mood), and anxiety were statistically associated with greater caffeine intake (P < 0.05). Conclusions As caffeine is commonly consumed and our study showed that its intake was associated with depressive symptoms and higher levels of anxiety in college students, further studies are needed to determine a possible causality, so that measures may be taken to educate these students about alternative methods for increasing energy and alertness.

Dietary phytochemical index in relation to risk of glioma: a case-control study in Iranian adults

BACKGROUND & AIM

No study is available that explores the association of dietary phytochemical index (DPI) with glioma. The objective of the current study was to assess this association in Iranian adults.

METHODS

This hospital-based case-control study included 128 newly-diagnosed cases of glioma and 256 age- and sex-matched controls. Data collection on dietary intakes was done using a 123-item validated food frequency questionnaire. Calculation of DPI was done as (dietary energy derived from phytochemical-rich foods (kcal)/total daily energy intake (kcal)) × 100. Logistic regression models were used to examine the association between DPI and glioma.

RESULTS

Individuals in the top tertile of DPI were more likely to be older and female. Before taking potential confounders into account, subjects in the top tertile of DPI tended to have a 40% reduced chance of glioma than those in the bottom tertile (OR: 0.60; 95% CI: 0.35-1.02, P = 0.06). After controlling for age, sex, energy intake, several demographic variables and dietary intakes, the association between DPI and glioma became strengthened (OR: 0.43; 95% CI: 0.19-0.97, P = 0.04).

CONCLUSION

High intakes of phytochemical-rich foods were associated with a lower risk of glioma in adults. High consumption of phytochemical-rich foods might be recommended to prevent glioma. However, further studies with a prospective design are needed to confirm our findings.

Tea Consumption and Depression from Follow Up in the Singapore Longitudinal Ageing Study

OBJECTIVES

Experimental evidence suggest that tea polyphenols have anti-depressant effect and tea consumption may reduce the risk and severity of depression. We investigated whether tea consumption was associated with changes in depressive symptoms over time among Asian older adults.

DESIGN

Population-based prospective cohort study with mean 4 years of follow up.

SETTING

Singapore Longitudinal Ageing Study (SLAS) of community-living older persons.

PARTICIPANTS

3177 participants overall (mean age 67 years) and 3004 participants who were depression-free at baseline.

MEASUREMENTS

Baseline tea consumption which include Chinese (black, oolong or green) tea or Western (mixed with milk) tea and change in Geriatric Depression Scale (GDS) measure of depression. Incident depression was defined by GDS≥5, and GDS depression improvement or deterioration by GDS change of ≥4 points. Estimated odds ratio and 95% confidence intervals (OR, 95%CI) were adjusted for baseline age, sex, ethnicity, education, housing type, single/divorced/widowed, living alone, physical and social activity, smoking, alcohol, number of comorbidities, MMSE, and baseline GDS level.

RESULTS

Compared to non-tea drinkers, participants who consumed ≥3 cups of tea of all kinds were significantly less likely to have worsened GDS symptoms: OR=0.32, 95% CI=0.12, 0.84. Among baseline depression-free participants, the risk of incident GDS (≥5) depression was significantly lower (OR=0.34, 95%CI=0.13, 0.90) for daily consumption of all types of tea, and Chinese (black, oolong or green) tea (OR=0.46, 95%CI=0.21,0.99).

CONCLUSION

This study suggests that tea may prevent the worsening of existing depressive symptoms and the reduce the likelihood of developing threshold depression.

Prospective association of soft drink consumption with depressive symptoms

OBJECTIVE

Consumption of soft drinks has become a serious public health issue worldwide. However, prospective evidence is limited regarding the relationship between soft drink consumption and depression, especially in Asia. The aim of this study was to investigate the prospective association between soft drink consumption and the development of depressive symptoms.

METHODS

We evaluated an occupational cohort of 935 adults in Japan (2012-2016), who were free from depressive symptoms at baseline and attended a 3-y follow-up assessment. Soft drink consumption was assessed using a self-administered diet history questionnaire. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression scale. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated from multivariate logistic regression analysis controlling for sociodemographic, lifestyle, dietary, and occupational covariates.

RESULTS

Over the 3-y study period, 16.9% (158 cases) of the study participants reported depressive symptoms. Higher soft drink consumption was associated with higher odds of depressive symptoms. The multivariable-adjusted OR was 1.91 (95% CI, 1.11-3.29; P_trend = 0.015) when comparing soft drink consumption of ≥4 cups/wk with consumption of <1 cup/wk.

CONCLUSION

The present results suggested that greater consumption of soft drinks would increase the likelihood of exhibiting depressive symptoms.

Effects of Polyphenols in a Mediterranean Diet on Symptoms of Depression: A Systematic Literature Review

Depression is a mood disorder which currently affects 350 million individuals worldwide. Recently, research has suggested a protective role of diet for depression. The Mediterranean-style dietary pattern has been highlighted in several systematic reviews as a promising candidate for reducing depressive symptoms. It has been speculated that this could be due to the high polyphenol content of foods commonly found in the diet. Therefore, the aim of this review was to assess the effects of polyphenols found in a Mediterranean diet on the symptoms of depression. A systematic literature review was conducted of original research which assessed the role of polyphenols on the symptoms of depression in humans. The following databases were searched: PROQUEST, SCOPUS (Elsevier), MEDLINE (EBSCO), CINAHL, and EMBase, up to 18 February, 2019. The inclusion criteria consisted of both observational and experimental research in adults aged 18-80 y that assessed depression scores in relation to polyphenol intake. A total of 37 studies out of 12,084 met the full inclusion criteria. Of these, 17 were experimental studies and 20 were observational studies. Several different polyphenols were assessed including those from tea, coffee, citrus, nuts, soy, grapes, legumes, and spices. Twenty-nine of the studies found a statistically significant effect of polyphenols for depression. This review has found both an association between polyphenol consumption and depression risk, as well as evidence suggesting polyphenols can effectively alleviate depressive symptoms. The review uncovered gaps in the literature regarding the role of polyphenols for depressive symptoms in both young adults and men. This review was registered at www.crd.york.ac.uk/PROSPERO as CRD42019125747.

Prospective study on the association between dietary non-enzymatic antioxidant capacity and depressive symptoms

BACKGROUND & AIMS

Oxidative stress has been suggested to play an important role in the pathophysiology of depression, and a diet high in antioxidants may improve mood. However, studies addressing this issue are scarce. The aim of this cohort study was to investigate the prospective association between dietary non-enzymatic antioxidant capacity (NEAC) in overall diet and depressive symptoms in Japanese employees. Additionally, we examined the association separated by dietary NEAC sources.

METHOD

Participants were 911 workers without depressive symptoms at baseline and participated in 3-y follow-up survey. Dietary NEAC was determined from a database of NEAC measurements obtained by ferric reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC). Dietary NEAC was calculated by multiplying the estimated NEAC values with the consumed amount and summing up those values. Depressive symptoms were assessed using the Center for Epidemiologic Studies Depression Scale. Logistic regression was used to estimate odds ratios of depressive symptoms according to overall NEAC and separately from foods and beverages.

RESULTS

At 3-y follow-up, 153 (16.8%) workers were newly identified as having depressive symptom. No significant associations were found between higher level of overall dietary NEAC and decreased risk of depressive symptoms after adjustment for potential confounders (overall: FRAP, P for trend = 0.19 and ORAC, P for trend = 0.20). Likewise, neither higher dietary NEAC from foods nor beverages were related with lower depressive symptoms.

CONCLUSION

Our findings did not support an inverse association between dietary NEAC and the risk of depressive symptoms in Japanese workers.

The sources and mechanisms of bioactive ingredients in coffee

Coffee bioactive components include caffeine, chlorogenic acids (CGAs), trigonelline, tryptophan alkaloids, diterpenes and other secondary metabolites. During roasting, coffee metabolites undergo complex Maillard reactions, producing melanoidins and other degradation products, the most controversial among which is acrylamide, an ingredient widely found in baked food and listed as a second class carcinogen. Green and roasted coffee ingredients have good biological activities for the prevention of cardiovascular disease, and antibacterial, anti-diabetic, neuroprotection, and anti-cancer activities. To better understand the relationship between coffee ingredients and human health, and to effectively use the active ingredients, it is essential to understand the sources of coffee active ingredients and their mechanisms of action in the organism. This paper systematizes the available information and provides a critical overview of the sources of coffee active ingredients and the mechanisms of action in vivo or in vitro, and their combined effects on common human diseases.

The Gut Microbiota Links Dietary Polyphenols With Management of Psychiatric Mood Disorders

The pathophysiology of depression is multifactorial yet generally aggravated by stress and its associated physiological consequences. To effectively treat these diverse risk factors, a broad acting strategy is required and is has been suggested that gut-brain-axis signaling may play a pinnacle role in promoting resilience to several of these stress-induced changes including pathogenic load, inflammation, HPA-axis activation, oxidative stress and neurotransmitter imbalances. The gut microbiota also manages the bioaccessibility of phenolic metabolites from dietary polyphenols whose multiple beneficial properties have known therapeutic efficacy against depression. Although several potential therapeutic mechanisms of dietary polyphenols toward establishing cognitive resilience to neuropsychiatric disorders have been established, only a handful of studies have systematically identified how the interaction of the gut microbiota with dietary polyphenols can synergistically alleviate the biological signatures of depression. The current review investigates several of these potential mechanisms and how synbiotics, that combine probiotics with dietary polyphenols, may provide a novel therapeutic strategy for depression. In particular, synbiotics have the potential to alleviate neuroinflammation by modulating microglial and inflammasome activation, reduce oxidative stress and balance serotonin metabolism therefore simultaneously targeting several of the major pathological risk factors of depression. Overall, synbiotics may act as a novel therapeutic paradigm for neuropsychiatric disorders and further understanding the fundamental mechanisms of gut-brain-axis signaling will allow full utilization of the gut microbiota's as a therapeutic tool.

Linking What We Eat to Our Mood: A Review of Diet, Dietary Antioxidants, and Depression

Studies have shown that diet and nutrition play significant roles in the prevention of depression and its clinical treatment. The present review aims to provide a clear understanding of the associations between diet patterns, specific foods, nutrients such as antioxidants, and depression. As a result, balanced dietary patterns such as the Mediterranean diet and certain foods such as fish, fresh vegetables, and fruits have been associated with a lower risk of depression or depressive symptoms, while high-fat Western diets and sugar-sweetened beverages have been associated with higher risk of depression or depressive symptoms. Dietary antioxidants such as green tea polyphenols or isoflavonoid intake have been negatively associated with depression or depressive symptoms. It is concluded that diet patterns, specific foods, and antioxidants play important roles in the prevention and clinical treatment of depression.

Association between tea consumption and depressive symptom among Chinese older adults

Background

Despite accumulating evidence on the protective effect of tea consumption against depression, studies specifically focusing on the elderly population are yet limited. This paper examined the association between the frequency and duration of tea drinking and depressive symptoms of older adults by gender and age groups, based on a nationally representative sample in China.

Method

The study employed the panel data from 2005, 2008/2009, 2011/2012 and 2014 waves of Chinese Longitudinal Healthy Longevity Survey (CLHLS). We used the frequency and consistency of tea drinking behaviors to identify four types of tea consumption amongst Chinese seniors. Depressive symptoms were assessed by a five-item scale. Linear mixed effects models were applied.

Results

We found that consistent and frequent tea-drinking was associated with significantly less depressive symptoms, and such impact was partially mediated by socioeconomic status, health behavior, physical health, cognitive function, and social engagement. However, the association was only significant for males and the oldest-old, rather than females and younger elders.

Conclusions

Consistent and frequent tea-drinking may effectively reduce the risk of depressive symptoms for the Chinese elderly. The promotion of the traditional lifestyle of tea drinking could be a cost-effective way towards healthy aging for China.

Electronic supplementary material

The online version of this article (10.1186/s12877-019-1259-z) contains supplementary material, which is available to authorized users.

Intake of Coffee Associated With Decreased Depressive Symptoms Among Elderly Japanese Women: A Multi-Center Cross-Sectional Study

Background

Depression in elderly people is a major global concern around the world. Epidemiological evidence of the association of beverages with depressive symptoms has received research attention; however, epidemiological studies on the association of coffee and green tea consumption with depressive symptoms among the elderly population are limited. The objective of this study is to cross-sectionally examine the association of depressive symptoms with the intake of coffee, green tea, and caffeine and to verify the antidepressant effect of caffeine.

Methods

The subjects were 1,992 women aged 65–94 years. Intakes of coffee, green tea, and caffeine, as well as depressive symptoms, were assessed with a validated brief dietary history questionnaire (BDHQ) and the Center for Epidemiologic Studies Depression Scale (CES-D), respectively. Multiple logistic regression analysis was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for depressive symptoms with adjustments for potential confounders.

Results

Coffee intake was associated with a lower prevalence of depressive symptoms, the ORs of which for the 4th versus the 1st quartiles of intake was 0.64 (95% CI, 0.46–0.88, P for trend = 0.01) in a fully adjusted model. Caffeine intake was marginally associated with depressive symptoms, but the association was not statistically significant (OR 0.75; 95% CI, 0.55–1.02, P for trend = 0.058).

Conclusion

The result suggests that the inverse association of coffee intake with depressive symptoms might be associated with not only caffeine intake but also some other substances in coffee or factors related to coffee intake. Because of the cross-sectional design of the present study, longitudinal studies are required to confirm the present finding.

Lifelong exposure to caffeine increases anxiety-like behavior in adult mice exposed to tobacco smoke during adolescence

Caffeine and tobacco smoke are among the most frequently self-administered licit psychoactive drugs in the world. Both drugs affect anxiety levels, however, little is known on the impact of the dual exposure in the adolescent brain, the period during which smoking begins. Considering that anxiety is a relevant factor for smoking maintenance and relapse, we investigated the effects of lifelong exposure to caffeine on anxiety levels of Swiss mice exposed to tobacco smoke during adolescence. Caffeine was administrated during all prenatal and postnatal life (CAF, 0.1 g/l to drink). From postnatal day 30-45, animals were exposed to tobacco smoke (SMK, whole body exposure, 8 h/day) generated from research cigarettes type 3R4F (nicotine = 0.73 mg/per cigarette). Four groups were analyzed: (1) CAF + SMK exposure; (2) SMK exposure; (3) CAF exposure; (4) Control. Anxiety levels were assessed in the elevated plus maze at the end of smoke exposure (PN45), at short- (PN55) and long-term (PN75) withdrawal. Caffeine exposure reduced decision making time (time in center of maze) during adolescence (PN45 and PN55). In addition, caffeine increased anxiety-like behavior during long-term tobacco smoke withdrawal. The present study provides experimental evidence that caffeine and tobacco smoke during adolescence interact resulting in emotional dysregulation during tobacco smoke withdrawal. Particularly, increased anxiety-like behavior during long-term withdrawal in CAF + SMK animals demonstrates late-emergent effects. In this sense, our data suggest that lifelong caffeine exposure may be an important factor in tobacco relapse.

Inverse association between caffeine intake and depressive symptoms in US adults: data from National Health and Nutrition Examination Survey (NHANES) 2005-2006

The objective of this study was to examine the association between caffeine consumption and depressive symptoms. We used data from the 2005-06 National Health and Nutritional Examination Surveys (NHANES). A total of 4737 individuals aged ≥ 18 years who answered the caffeine intake and PHQ-9 questionnaires were selected for this study. Depressive symptoms were assessed using the 9-item Patient Health Questionnaire (PHQ-9) with total scores between 0 and 27. Those with PHQ-9 total scores ≥ 10 were considered as having clinically relevant depression. To investigate the association of caffeine intake and PHQ-9 scores, a multiple logistic regression was used in different models. The overall weighted prevalence of depression was 5.5% (4.3% in men and 6.6% in women). After controlling for potential confounders (age, sex, family PIR, education, marital status, disease history, sleep disorders, thyroid problems, physical activity, social support, smoking, total energy, and cholesterol, retinol, vitamin A, beta-carotene, beta-criptoxanthin, vitamin B1, iron, and phosphorus levels), a significant nonlinear inverse association between caffeine consumption and PHQ-9 scores was observed. In conclusion, caffeine's psychostimulant properties appear to protect against depressive symptoms; however, additional prospective studies are required to ascertain whether or not caffeine consumption can lead to a decrease in depressive symptoms.

Impact of genetic variations in ADORA2A gene on depression and symptoms: a cross-sectional population-based study

Genetic variants involved in adenosine metabolism and its receptors were associated with increased risk for psychiatric disorders, including anxiety, depression, and schizophrenia. Here, we examined an association between a single nucleotide polymorphism in A_2A receptor gene (ADORA2A, rs2298383 SNP) with current depressive episode and symptom profile. A total of 1253 individuals from a cross-sectional population-based study were analyzed by the Mini International Neuropsychiatric Interview 5.0. Our data showed that the TT genotype of ADORA2A rs2298383 SNP was associated with reduced risk for depression when compared to the CC/CT genotypes (p = 0.020). This association remained significant after adjusting for confounding variables such as smoking, gender, socioeconomic class, and ethnicity (OR = 0.631 (95% CI 0.425-0.937); p = 0.022). Regarding the symptoms associated with depression, we evaluated the impact of the ADORA2A SNP in the occurrence of sad/discouraged mood, anhedonia, appetite changes, sleep disturbances, motion changes, energy loss, feelings of worthless or guilty, difficulty in concentrating, and presence of bad thoughts. Notably, the TT genotype was independently associated with reduced sleep disturbances (OR = 0.438 (95% CI 0.258-0.743); p = 0.002) and less difficulty in concentrating (OR = 0.534 (95% CI 0.316-0.901; p = 0.019). The cross-sectional design cannot evaluate the cause-effect relationship and did not evaluate the functional consequences of this polymorphism. Our data support an important role for ADORA2A rs2298383 SNP in clinical heterogeneity associated with depression. The presence of the TT genotype was associated with decrease risk for current depression and disturbances in sleep and attention, two of the most common symptoms associated with this disorder.

Bioactive Constituents in Caffeinated and Decaffeinated Coffee and Their Effect on the Risk of Depression—A Comparative Constituent Analysis Study

Coffee, a popular beverage throughout the world, has been shown to have numerous beneficial health effects, including reducing the risk of developing depression. This effect has only been shown with the consumption of caffeinated coffee and not decaffeinated coffee or caffeine alone and one of many hypotheses attributes this to the loss of key constituents during the decaffeination process. The aim of this study was to investigate whether any of the key bioactive coffee constituents with known anti-oxidant and anti-inflammatory effects are lost during the decaffeination process. The analysis of nine caffeinated and nine decaffeinated samples of various brands and batches of commonly consumed coffee in Australia using HPLC analysis found that, with the exception of caffeine, there were no significant differences in the quantity of other key bioactive coffee constituents in caffeinated and decaffeinated coffee. These results suggest that there may be an alternative explanation for the observed inverse correlation between caffeinated coffee consumption and the risk of developing depression.

Coffee Consumption and the Risk of Depression in a Middle-Aged Cohort: The SUN Project

Coffee is one of the most widely consumed drinks around the world, while depression is considered the major contributor to the overall global burden of disease. However, the investigation on coffee consumption and depression is limited and results may be confounded by the overall dietary pattern. We assessed the relationship between coffee intake and the risk of depression, controlling for adherence to the Mediterranean diet. We studied 14,413 university graduates of the 'Seguimiento Universidad de Navarra' (SUN) cohort, initially free of depression. We evaluated coffee consumption using a validated food-frequency questionnaire (FFQ). Incident depression cases were adjudicated only if the participant met two criteria simultaneously: (a) validated physician-diagnosed depression together with (b) new onset of habitual antidepressant use. Both criteria were needed; participants meeting only one of them were not classified as cases. Participants who drank at least four cups of coffee per day showed a significantly lower risk of depression than participants who drank less than one cup of coffee per day (HR: 0.37 (95% CI 0.15⁻0.95)). However, overall, we did not observe an inverse linear dose⁻response association between coffee consumption and the incidence of depression (p for trend = 0.22).

Green Tea, Coffee, and Caffeine Consumption Are Inversely Associated with Self-Report Lifetime Depression in the Korean Population

This study investigated the associations of green tea, coffee, and caffeine consumption with self-report lifetime depression in the Korean population using data from the Korean National Health and Nutrition Examination Survey. In total, 9576 participants (3852 men and 5724 women) aged 19 years or older were selected for the present study. Green tea, coffee, and caffeine consumption levels were assessed with a validated food frequency questionnaire. Multivariate logistic regression analysis was used to determine the odds ratios (OR) and 95% confidence intervals (CIs) for depression according to green tea, coffee, and caffeine consumption. Frequent green tea consumers (≥3 cups/week) had 21% lower prevalence of depression (OR = 0.79, 95% CI = 0.63–0.99, p for trend = 0.0101) than green tea non-consumers after adjustment for potential confounders. Likewise, frequent coffee drinkers (≥2 cups/day) had 32% lower prevalence of depression (OR = 0.68, 95% CI = 0.55–0.85, p for trend = 0.0026) than coffee non-drinkers after adjustment for potential confounders. Also, participants in the highest quartile of caffeine consumption had 24% lower prevalence of depression than those in the lowest quartile (OR = 0.76, 95% CI = 0.62–0.92, p for trend = 0.0032). Frequent consumption of green tea, coffee, or caffeine was associated with a reduced prevalence of self-report lifetime depression in Korean adults. A prospective study and randomized clinical trials should be conducted to confirm the inverse relationships of green tea and coffee consumption with risk of depression.

Mediterranean diet and depression among older individuals: The multinational MEDIS study

BACKGROUND

Depression has been linked to a large and growing economic and societal burden worldwide. In Europe, depression is one of the most frequent mental disorders across all age groups, but particularly in people aged 65 years and over, and higher depressive symptoms have been reported among individuals with chronic diseases (e.g., diabetes and heart disease).

AIM

To evaluate the role of adherence to the Mediterranean diet (MedDiet) in depression in a sample of older people living in the Mediterranean basin.

METHODS

Standard procedures were used to determine socio-demographic, lifestyle, and clinical characteristics of the participants, as well as their dietary habits, and depressive symptoms were evaluated using the Geriatric Depression Scale (GDS). Multi-adjusted logistic and linear regression analyses were carried out to evaluate the associations between participants' characteristics and depression.

RESULTS

Participants classified as having mild or severe depression were less educated and physically active, and more diabetic, and they reported less adherence to the MedDiet. Adherence to the MedDiet was associated with the absence of depression [(OR, 95% CI): 0.65, 0.50-0.85]. In addition, daily tea drinking was also related to the absence of depression [(OR, 95% CI): 0.51, 0.40-0.65].

CONCLUSIONS

Greater adherence to the MedDiet and daily tea drinking seem to have a beneficial effect on depressive symptoms in older adults.

Effect of Green Tea Phytochemicals on Mood and Cognition

BACKGROUND

Green tea is traditionally known to induce mental clarity, cognitive function, physical activation and relaxation. Recently, a special green tea, matcha tea, is rapidly gaining popularity throughout the world and is frequently referred to as a mood- and brain food. Matcha tea consumption leads to much higher intake of green tea phytochemicals compared to regular green tea. Previous research on tea constituents caffeine, L-theanine, and epigallocatechin gallate (EGCG) repeatedly demonstrated benefits on mood and cognitive performance. These effects were observed when these phytochemicals were consumed separately and in combination.

METHODS

A review was conducted on 49 human intervention studies to summarize the research on acute psychoactive effects of caffeine, L-theanine, and EGCG on different dimensions of mood and cognitive performance.

CONCLUSION

Caffeine was found to mainly improve performance on demanding long-duration cognitive tasks and self-reported alertness, arousal, and vigor. Significant effects already occurred at low doses of 40 mg. L-theanine alone improved self-reported relaxation, tension, and calmness starting at 200 mg. L-theanine and caffeine combined were found to particularly improve performance in attention-switching tasks and alertness, but to a lesser extent than caffeine alone. No conclusive evidence relating to effects induced by EGCG could be given since the amount of intervention studies was limited. These studies provided reliable evidence showing that L-theanine and caffeine have clear beneficial effects on sustained attention, memory, and suppression of distraction. Moreover, L-theanine was found to lead to relaxation by reducing caffeine induced arousal.

Tea, cocoa, coffee, and affective disorders: vicious or virtuous cycle?

BACKGROUND

The prevalence of psychiatric disorders is increasing worldwide, which underscores the importance of increasing research in this field, in terms of better detection, prevention based on improvement of lifestyle and diet, and effectiveness of treatment. Increasing evidence suggest that diet and exercise can affect proper neuronal development and physiology and protect the brain from neurological illnesses or injuries. Of note, cocoa, tea, and coffee are being actively investigated because they are rich in (poly)phenolic compounds that can modulate mental health, namely brain plasticity, behavior, mood, depression, and cognition.

METHODS

We here systematically review human studies conducted on tea, cocoa, and coffee as related to affective disorders such as depression and anxiety. We carried out a systematic literature search in April 2016, using MEDLINE, on data from the last 10 years. After screening 955 articles, we selected 17 articles that met the criteria of being human studies and that used whole foods or their components.

RESULTS

The results of our systematic review indicate that consumption of tea, cocoa, or coffee might have protective effects against depression.

CONCLUSIONS

Even though this is encouraging, it should be underscored that the near totality of the current evidence comes from observational studies. Ad-hoc human trials and mechanistic, basic science studies are needed before we can provide sound advice to the public.

Food-based diet quality score in relation to depressive symptoms in young and middle-aged Japanese women

Only a few studies have focused on the association between overall diet, rather than intakes of individual nutrients or foods, and depressive symptoms in Japanese. This cross-sectional study examined associations between a diet quality score and depressive symptoms in 3963 young (age 18 years) and 3833 middle-aged (mean age 47·9 (sd 4·2) years) Japanese women. Dietary information was collected using a diet history questionnaire. A previously developed diet quality score was computed mainly based on the Japanese Food Guide Spinning Top. The prevalence of depressive symptoms was 22·0 % for young women and 16·8 % for middle-aged women, assessed as a Center for Epidemiologic Studies Depression (CES-D) score ≥23 and ≥19, respectively. As expected, the diet quality score was associated positively with intakes of ‘grain dishes’, ‘vegetable dishes’, ‘fish and meat dishes’, ‘milk’ and ‘fruits’ and inversely with intakes of energy from ‘snacks, confection and beverages’ and Na from seasonings. After adjustment for potential confounders, OR for depressive symptoms in the highest v. lowest quintiles of the diet quality score was 0·65 (95 % CI 0·50, 0·84) in young women (Pfor trend=0·0005). In middle-aged women, the corresponding value was 0·59 (95 % CI 0·45, 0·78) (Pfor trend<0·0001). Analyses where the diet quality and CES-D scores were treated as continuous variables also showed inverse associations. In conclusion, this cross-sectional study showed that a higher diet quality score was associated with a lower prevalence of depressive symptoms in young and middle-aged Japanese women. Prospective studies are needed to confirm a public health relevance of this finding.

Evaluation of the potential antidepressant effects of soybean isoflavones

OBJECTIVE

The aim of the study was to determine whether isoflavones affect depressive symptoms in women.

METHODS

Literature searches were conducted to identify clinical and epidemiologic studies that evaluated the impact of soy intake and isoflavone exposure on depressive symptoms. References from identified studies were also evaluated to identify eligible studies.

RESULTS

Only limited epidemiologic research has evaluated the impact of soy or isoflavone intake on depression although several studies from China and Japan did find soy product intake was inversely related to risk of depression. Often times, soy was, however, evaluated only as a component of a summative dietary pattern (eg, a "Japanese" or "Healthy" diet). Of the 20 intervention studies identified, roughly half found statistically significant reductions in depressive symptoms in response to isoflavones although several had design weakness. Of those studies reporting a lack of antidepressant effects of isoflavones, design limitations likely contributed to the lack of efficacy. In all but two trials, assessment of depression was, however, a secondary outcome. It is notable that both trials in which depression was a primary outcome found isoflavones significantly improved symptoms.

CONCLUSIONS

Although the data are inconsistent and limited, the clinical and epidemiologic evidence suggests that isoflavones may offer a safe, well-tolerated option for management of depression. Furthermore, the intervention doses used in the clinical studies fall well within the dietary range. The extant literature reveals key design features for future studies, which based upon the results of this review, are clearly warranted.

How does adenosine control neuronal dysfunction and neurodegeneration?

The adenosine modulation system mostly operates through inhibitory A₁ (A₁ R) and facilitatory A_2A receptors (A_2A R) in the brain. The activity-dependent release of adenosine acts as a brake of excitatory transmission through A₁ R, which are enriched in glutamatergic terminals. Adenosine sharpens salience of information encoding in neuronal circuits: high-frequency stimulation triggers ATP release in the 'activated' synapse, which is locally converted by ecto-nucleotidases into adenosine to selectively activate A_2A R; A_2A R switch off A₁ R and CB1 receptors, bolster glutamate release and NMDA receptors to assist increasing synaptic plasticity in the 'activated' synapse; the parallel engagement of the astrocytic syncytium releases adenosine further inhibiting neighboring synapses, thus sharpening the encoded plastic change. Brain insults trigger a large outflow of adenosine and ATP, as a danger signal. A₁ R are a hurdle for damage initiation, but they desensitize upon prolonged activation. However, if the insult is near-threshold and/or of short-duration, A₁ R trigger preconditioning, which may limit the spread of damage. Brain insults also up-regulate A_2A R, probably to bolster adaptive changes, but this heightens brain damage since A_2A R blockade affords neuroprotection in models of epilepsy, depression, Alzheimer's, or Parkinson's disease. This initially involves a control of synaptotoxicity by neuronal A_2A R, whereas astrocytic and microglia A_2A R might control the spread of damage. The A_2A R signaling mechanisms are largely unknown since A_2A R are pleiotropic, coupling to different G proteins and non-canonical pathways to control the viability of glutamatergic synapses, neuroinflammation, mitochondria function, and cytoskeleton dynamics. Thus, simultaneously bolstering A₁ R preconditioning and preventing excessive A_2A R function might afford maximal neuroprotection. The main physiological role of the adenosine modulation system is to sharp the salience of information encoding through a combined action of adenosine A_2A receptors (A_2A R) in the synapse undergoing an alteration of synaptic efficiency with an increased inhibitory action of A₁ R in all surrounding synapses. Brain insults trigger an up-regulation of A_2A R in an attempt to bolster adaptive plasticity together with adenosine release and A₁ R desensitization; this favors synaptotocity (increased A_2A R) and decreases the hurdle to undergo degeneration (decreased A₁ R). Maximal neuroprotection is expected to result from a combined A_2A R blockade and increased A₁ R activation. This article is part of a mini review series: "Synaptic Function and Dysfunction in Brain Diseases".

Tea consumption is inversely associated with depressive symptoms in the elderly: A cross-sectional study in eastern China

BACKGROUND

Epidemiological studies suggest that higher tea consumption was associated with lower risk of depressive symptoms, but this has not been found consistently. Moreover, the effect of different types of tea on depressive symptoms needs to be further explored. This study aimed to examine the association between tea consumption and depressive symptoms in Chinese elderly.

METHODS

We analyzed the baseline data from Zhejiang Major Public Health Surveillance Program including 9371 participants. Depressive symptoms was assessed through the application of Patient Health Questionnaire-9 scale (PHQ-9). Logistic regression models, controlled for an extensive range of potential confounders, were generated to evaluate the association between tea consumption and risk of depressive symptoms.

RESULTS

The black tea drinkers had a significantly decreased risk of depressive symptoms (p<0.01), whereas no association was found in green tea drinkers. Compared with non-drinkers, the adjusted ORs (95% CIs) were 0.48 (0.23, 0.99) and 0.35 (0.17, 0.72) for participants consuming <3 cups and ≥3 cups of black tea per day, respectively (P for trend: <0.01). A linear association between concentration of black tea and depressive symptoms was also confirmed in our study.

LIMITATIONS

Cross-sectional data could not make a causation conclusion, and the observed association in our study could not be ascribed to any specific component in tea.

CONCLUSIONS

Our results indicated that higher black tea consumption was associated with a lower prevalence of depressive symptoms in the elderly.

The Microbiome and Mental Health: Looking Back, Moving Forward with Lessons from Allergic Diseases

Relationships between gastrointestinal viscera and human emotions have been documented by virtually all medical traditions known to date. The focus on this relationship has waxed and waned through the centuries, with noted surges in interest driven by cultural forces. Here we explore some of this history and the emerging trends in experimental and clinical research. In particular, we pay specific attention to how the hygiene hypothesis and emerging research on traditional dietary patterns has helped re-ignite interest in the use of microbes to support mental health. At present, the application of microbes and their structural parts as a means to positively influence mental health is an area filled with promise. However, there are many limitations within this new paradigm shift in neuropsychiatry. Impediments that could block translation of encouraging experimental studies include environmental forces that work toward dysbiosis, perhaps none more important than westernized dietary patterns. On the other hand, it is likely that specific dietary choices may amplify the value of future microbial-based therapeutics. Pre-clinical and clinical research involving microbiota and allergic disorders has predated recent work in psychiatry, an early start that provides valuable lessons. The microbiome is intimately connected to diet, nutrition, and other lifestyle variables; microbial-based psychopharmacology will need to consider this contextual application, otherwise the ceiling of clinical expectations will likely need to be lowered.