Association Between Regular Laxative Use and Incident Dementia in UK Biobank Participants

Constipation and risk of death and cardiovascular events in patients on hemodialysis

BACKGROUND

Constipation is a common gastrointestinal disorder and is often accompanied by alteration in the gut microbiota. Recently, several studies have disclosed its association with an increased risk of cardiovascular disease and mortality in the general population. Despite the high prevalence of constipation, data on the clinical impact of constipation in patients with chronic kidney disease are limited. We aimed to explore the prevalence of constipation and its association with cardiovascular disease in chronic kidney disease using a nationally representative cohort of hemodialysis patients.

METHODS

This study used hemodialysis quality assessment and health insurance claims data from patients undergoing maintenance hemodialysis in South Korea. Chronic constipation was defined using the total number of laxatives prescribed during the 1-year baseline period. The primary outcome was a composite of acute ischemic stroke, hemorrhagic stroke, myocardial infarction, or all-cause death. Secondary outcomes were the individual components of the primary outcome.

RESULTS

Among 35,230 patients on hemodialysis, 9,133 (25.9%) were identified as having constipation. During a median follow-up of 5.4 years, patients with constipation had a 15% higher incidence of the composite outcome, 16% higher incidence of ischemic stroke, and 14% higher all-cause mortality, after multivariate adjustment.

CONCLUSION

Chronic constipation requiring laxatives was associated with a higher risk of the composite outcome of cardiovascular events or all-cause death in patients on hemodialysis. Further studies are needed to confirm whether constipation is an independent predictor or a possible causal factor of cardiovascular disease.

Associations among dietary 1-carbon metabolism nutrients, genetic risk, and Alzheimer disease: a prospective cohort study

BACKGROUND

The associations between 1-carbon metabolism (OCM) nutrients (methionine, folate, vitamin B-6, and vitamin B-12) and Alzheimer disease (AD) remains inconclusive.

OBJECTIVES

This study aimed to investigate the association of dietary OCM nutrients with subsequent risk of AD and further assess whether participants with high genetic risk for AD might benefit from dietary OCM nutrients.

METHODS

We analyzed data from 192,214 participants who completed at least one 24-h dietary questionnaire and had no previous history of AD based on the UK Biobank. Nutrients intake was calculated using McCance and Widdowson's The Composition of Food and USDA's Food and Nutrient Database for Dietary Studies. Cox proportional models with restricted cubic splines were applied to explore the associations.

RESULTS

Over a median follow-up of 13.35 y, 959 cases of AD (41 early-onset cases and 918 late-onset cases) were identified. Compared with those in the low-intake OCM group (quartile 1), participants in the high-intake OCM group (quartile 4) had reduced risk of developing AD. The corresponding hazard ratios (HRs) and 95% confidence intervals (CIs) for methionine, folate, vitamin B-6, and vitamin B-12 intake were 0.66 (0.54, 0.80), 0.71 (0.58, 0.87), 0.71 (0.59, 0.87), and 0.77 (0.64, 0.93), respectively. Similar associations were observed in late-onset AD. In early-onset AD, high methionine and vitamin B-12 intake were associated with 70% (HR: 0.30; 95% CI: 0.10, 0.86) and 71% (HR: 0.29; 95% CI: 0.09, 0.96) reduction in risk, respectively. Participants with low genetic risk and high OCM nutrients intake had >75% reduced AD risk compared with high-risk, low-intake participants.

CONCLUSIONS

In this prospective cohort study, we found that higher intake of OCM nutrients is associated with reduced risk of AD. Participants with high genetic risk of AD are more likely to benefit from dietary OCM nutrients intake.

Slow gut transit increases the risk of Alzheimer's disease: An integrated study of the bi-national cohort in South Korea and Japan and Alzheimer's disease model mice

INTRODUCTION

Although the association between Alzheimer's disease (AD) and constipation is controversial, its causality and underlying mechanisms remain unknown.

OBJECTIVES

To investigate the potential association between slow gut transit and AD using epidemiological data and a murine model.

METHODS

We conducted a bi-national cohort study in South Korea (discovery cohort, N=3,130,193) and Japan (validation cohort, N=4,379,285) during the pre-observation period to determine the previous diagnostic history (2009-2010) and the follow-up period (2011-2021). To evaluate the causality, we induced slow gut transit using loperamide in 5xFAD transgenic mice. Changes in amyloid-beta (Aβ) and other markers were examined using ELISA, qRT-PCR, RNA-seq, and behavioral tests.

RESULTS

Constipation was associated with an increased risk of AD in the discovery cohort (hazard ratio, 2.04; 95% confidence interval [CI], 2.01-2.07) and the validation cohort (hazard ratio; 2.82; 95% CI, 2.61-3.05). We found that loperamide induced slower gut transit in 5xFAD mice, increased Aβ and microglia levels in the brain, increased transcription of genes related to norepinephrine secretion and immune responses, and decreased the transcription of defense against bacteria in the colonic tissue.

CONCLUSION

Impaired gut transit may contribute to AD pathogenesis via the gut-brain axis, thus suggesting a cyclical relationship between intestinal barrier disruption and Aβ accumulation in the brain. We propose that gut transit or motility may be a modifiable lifestyle factor in the prevention of AD, and further clinical investigations are warranted.

Relationship of Regular Laxative Use, Genetic Susceptibility of Depression, and Risk of Incident Depression in the General Population

Background: The relationship between laxative use and the risk of depression remains uncertain. We aimed to assess the prospective association of regular laxative use with the risk of incident depression and to examine whether genetic risk of depression modifies this association. Methods: Four hundred fifty thousand forty-five participants without depression at baseline and have complete information on laxative use from the UK Biobank were included. The study outcome was incident depression, derived from linkage to primary care records, hospital inpatient data, death register records, or self-reported medical conditions at follow-up visits. Results: During a median follow-up of 12.4 years, 18,651(4.1%) participants have developed depression. Regular laxative use was significantly associated with a higher risk of incident depression (vs. nonregular laxative use; adjusted hazard ratio [HR] = 1.78, 95% confidence interval [CI], 1.68-1.89). Genetic risk of depression did not significantly modify this association. The risk of incident depression increased with increasing types of laxatives used, with a HR of 1.89 (95%CI, 1.73-2.08) for use of single laxative type and 2.32 (95%CI, 1.82-2.96) for combined use of two or more laxative types (P for trend <0.001). The positive association between regular laxative use and incident depression was more pronounced in men (adjusted HR = 2.21, 95%CI, 1.96-2.48) versus women (adjusted HR = 1.67, 95%CI, 1.56-1.79; P interaction <0.001). Compared to those who did not use laxatives regularly and did not have constipation, participants who used laxatives regularly and had constipation had the highest risk of incident depression (adjusted HR = 2.33, 95%CI, 1.94-2.80). Conclusions: Regular laxative use was significantly associated with a higher risk of incident depression, especially in men.

Cardiovascular health and cancer mortality: evidence from US NHANES and UK Biobank cohort studies

BACKGROUND

The American Heart Association recently introduced a novel cardiovascular health (CVH) metric, Life's Essential 8 (LE8), for health promotion. However, the relationship between LE8 and cancer mortality risk remains uncertain.

METHODS

We investigated 17,076 participants from US National Health and Nutrition Examination Survey (US NHANES) and 272,727 participants from UK Biobank, all free of cancer at baseline. The CVH score, based on LE8 metrics, incorporates four health behaviors (diet, physical activity, smoking, and sleep) and four health factors (body mass index, lipid, blood glucose, and blood pressure). Self-reported questionnaires assessed health behaviors. Primary outcomes were mortality rates for total cancer and its subtypes. The association between CVH score (continuous and categorical variable) and outcomes was examined using Cox model with adjustments. Cancer subtypes-related polygenic risk score (PRS) was constructed to evaluate its interactions with CVH on cancer death risk.

RESULTS

Over 141,526 person-years in US NHANES, 424 cancer-related deaths occurred, and in UK Biobank, 8,872 cancer deaths were documented during 3,690,893 person-years. High CVH was associated with reduced overall cancer mortality compared to low CVH (HR 0.58, 95% CI 0.37-0.91 in US NHANES; 0.51, 0.46-0.57 in UK Biobank). Each one-standard deviation increase in CVH score was linked to a 19% decrease in cancer mortality (HR: 0.81; 95% CI: 0.73-0.91) in US NHANES and a 19% decrease (HR: 0.81; 95% CI: 0.79-0.83) in UK Biobank. Adhering to ideal CVH was linearly associated with decreased risks of death from lung, bladder, liver, kidney, esophageal, breast, colorectal, pancreatic, and gastric cancers in UK Biobank. Furthermore, integrating genetic data revealed individuals with low PRS and high CVH exhibited the lowest mortality from eight cancers (HRs ranged from 0.36 to 0.57) compared to those with high PRS and low CVH. No significant modification of the association between CVH and mortality risk for eight cancers by genetic predisposition was observed. Subgroup analyses showed a more pronounced protective association for overall cancer mortality among younger participants and those with lower socio-economic status.

CONCLUSIONS

Maintaining optimal CVH is associated with a substantial reduction in the risk of overall cancer mortality. Adherence to ideal CVH correlates linearly with decreased mortality risk across multiple cancer subtypes. Individuals with both ideal CVH and high genetic predisposition demonstrated significant health benefits. These findings support adopting ideal CVH as an intervention strategy to mitigate cancer mortality risk and promote healthy aging.

Prescription medication use in the 10 years prior to diagnosis of young onset Alzheimer's disease: a nationwide nested case-control study

BACKGROUND

Patients with young onset Alzheimer's disease (YOAD) face long diagnostic delays. Prescription medication use may provide insights into early signs and symptoms, which may help facilitate timely diagnosis.

METHODS

In a register-based nested case-control study, we examined medication use for everyone diagnosed with YOAD in a Danish memory clinic during 2016-2020 compared to cognitively healthy controls. Prescription medication use were grouped into 13 overall categories (alimentary tract and metabolism, blood and blood forming organs, cardiovascular system, dermatologicals, genitourinary system and sex hormones, systemic hormonal preparations, antiinfectives for systemic use, antineoplastic and immunomodulating agents, musculo-skeletal system, nervous system, antiparasitic products, respiratory system, and sensory organs). Further stratifications were done for predetermined subcategories with a use-prevalence of at least 5% in the study population. Conditional logistic regression produced odds ratios, which given the use of incidence-density matching is interpretable as incidence rate ratios (IRRs). The association between prescription medication use and subsequent YOAD diagnosis was examined in the entire 10-year study period and in three time-intervals.

RESULTS

The study included 1745 YOAD cases and 5235 controls. In the main analysis, several overall categories showed significant associations with YOAD in one or more time-intervals, namely blood and blood forming organs and nervous system. Prescription medication use in the nervous system category was increased for YOAD cases compared to controls already 10->5 years prior to diagnosis (IRR 1.17, 95% CI 1.05-1.31), increasing to 1.57 (95% CI 1.39-1.78) in the year preceding diagnosis. This was largely driven by antidepressant and antipsychotic use, and especially prominent for first-time users.

CONCLUSIONS

In this study, medication use in several categories was associated with YOAD. Onset of treatment-requiring psychiatric symptoms such as depression or psychosis in mid-life may serve as potential early indicators of YOAD.

Association between household size and risk of incident dementia in the UK Biobank study

Currently, the relationship between household size and incident dementia, along with the underlying neurobiological mechanisms, remains unclear. This prospective cohort study was based on UK Biobank participants aged ≥ 50 years without a history of dementia. The linear and non-linear longitudinal association was assessed using Cox proportional hazards regression and restricted cubic spline models. Additionally, the potential mechanisms driven by brain structures were investigated by linear regression models. We included 275,629 participants (mean age at baseline 60.45 years [SD 5.39]). Over a mean follow-up of 9.5 years, 6031 individuals developed all-cause dementia. Multivariable analyses revealed that smaller household size was associated with an increased risk of all-cause dementia (HR, 1.06; 95% CI 1.02-1.09), vascular dementia (HR, 1.08; 95% CI 1.01-1.15), and non-Alzheimer's disease non-vascular dementia (HR, 1.09; 95% CI 1.03-1.14). No significant association was observed for Alzheimer's disease. Restricted cubic splines demonstrated a reversed J-shaped relationship between household size and all-cause and cause-specific dementia. Additionally, substantial associations existed between household size and brain structures. Our findings suggest that small household size is a risk factor for dementia. Additionally, brain structural differences related to household size support these associations. Household size may thus be a potential modifiable risk factor for dementia.

Atrial fibrillation increases the risk of all-cause dementia, Alzheimer's disease, and vascular dementia: A cohort study of 373, 415 participants in the UK Biobank

BACKGROUND

Accumulated evidence has highlighted the association between atrial fibrillation and the risk of developing dementia.

METHODS

This current cohort study utilized data from the UK Biobank to explore the association between atrial fibrillation (AF) and all-cause dementia (ACD), encompassing its main subtypes (Alzheimer's disease (AD), and vascular dementia (VD)). Cox proportional hazards models were applied to examine the association of AF and dementia with its primary subtypes after adjusting for different sets of covariates. Hazard ratios (HRs) with 95 % confidential intervals (CIs) were estimated to quantify the associated risks. Competing risk model was applied in sensitivity analysis.

RESULTS

After exclusion, 373, 415 participants entered the primary analysis. Among these, 27, 934 (7.48 %) were with a history AF at baseline, while 345, 481 (92.52 %) were without. During a mean follow-up of 13.45 years, ACD was diagnosed in 1215 individuals with AF and 3988 individuals without AF. Participants with AF had higher risks of ACD (1.79 [1.67-1.91]), AD (1.48 [1.32-1.65]), and VD (2.46 [2.17-2.80]) in the fully adjusted Cox regression models. Results of subgroup and sensitivity analyses predominantly aligned with the positive associations in primary analysis.

LIMITATIONS

The applicability of our findings to diverse ethnicities might require careful consideration and the behind biological mechanisms need to be further revealed.

CONCLUSIONS

It indicated that people with atrial fibrillation had an increased future risk of all-cause dementia, Alzheimer's disease, vascular dementia. Atrial fibrillation screening and prevention strategies should take into account to prevent and delay the onset of dementia.

Constipation preceding depression: a population-based cohort study

Background

Constipation is generally considered a common physical symptom of depression or a side effect of antidepressant treatments. However, according to the gut-brain axis hypothesis, the association between depression and constipation might be bi-directional. This study investigated the association between premorbid constipation and depression.

Methods

We conducted a retrospective cohort study using data from UK Biobank. Individuals free of depression between 2006 and 2010 were included. Constipation status was determined using diagnostic codes from electronic health records or a baseline questionnaire. Data on covariates, including socio-demographic characteristics, lifestyle factors, health conditions, and regular medication use, were also collected through a baseline questionnaire. The primary outcome is incident depression, which was extracted from hospital inpatient admissions, primary care, self-report, and death data from baseline to 2022. The secondary outcome is depressive symptoms, which was assessed by Patient Health Questionnaire-9 (PHQ-9) from an online survey in 2016. Cox proportional hazard regression models were employed to assess the prospective association between constipation and incident depression. Logistic regression models were used to assess its association with depressive symptoms.

Findings

Among the 449,459 participants included in the study, 18,596 (4.1%) experienced constipation at baseline, and 18,576 (4.1%) developed depression over a median follow-up period of 12.3 years. Premorbid constipation is associated with a 2.28-fold higher risk of depression. After adjusting the covariates, we found those with constipation still had a 48% higher risk of developing depression (adjusted hazard ratio [aHR] 1.48; 95% CI, 1.41-1.56) than those without constipation. Self-reported and diagnosed constipation were both associated with a higher risk of depression, with the aHR being 1.42 (95% CI: 1.34-1.51) and 1.66 (95% CI: 1.51-1.82), respectively. Participants with constipation were more likely to report depressive symptoms than people without (adjusted odds ratio 2.18; 95% CI, 1.97-2.43). These findings remained consistent in sensitivity analyses.

Interpretation

Diagnosed and self-reported constipation are both prospectively associated with an elevated risk of depression. These explorative findings suggest that constipation may be an independent risk factor or a prodromal symptom of depression. Gastroenterologists and primary care physicians should pay more attention to the depressive symptoms of their constipation patients.

Funding

The Shenzhen Science and Technology Program and the Strategic Priority Research Program of Chinese Academy of Sciences.

Association Between Bowel Movement Pattern and Cognitive Function: Prospective Cohort Study and a Metagenomic Analysis of the Gut Microbiome

BACKGROUND AND OBJECTIVES

Little is known regarding the association between intestinal motility patterns and cognitive function in individuals who are baseline cognitively healthy. The gut microbiome may contribute to the association. We examined the association between bowel movement (BM) pattern and cognitive function and explored the role of the gut microbiome in explaining this association.

METHODS

In this prospective study, we leveraged 3 cohort studies, Nurses' Health Study (NHS), NHSII, and Health Professionals Follow-Up Study (HPFS). Participants reported BM frequency and subjective cognitive function. In a subset of NHSII participants, we assessed cognitive function using an objective neuropsychological battery. We profiled the gut microbiome in a subset of participants using whole-genome shotgun metagenomics. General linear models, Poisson regression, and logistic regression were used to quantify the association of BM frequency with different cognitive measurements.

RESULTS

We followed 112,753 men and women (women: 87.6%) with a mean age of 67.2 years at baseline (NHS: 76 years, NHSII: 59 years, HPFS: 75 years) for a median follow-up of 4 years (NHSII and HPFS: 4 years, NHS: 2 years). Compared with those with BM once daily, participants with BM frequency every 3+ days had significantly worse objective cognitive function, equivalent to 3.0 (95% confidence interval [CI],1.2-4.7) years of chronological cognitive aging. We observed similar J-shape dose-response relationships of BM frequency with the odds of subjective cognitive decline and the likelihood of having more subsequent subjective cognitive complaints (both p nonlinearity < 0.001). BM frequencies of every 3+ days and ≥twice/day, compared with once daily, were associated with the odds ratios of subjective cognitive decline of 1.73 (95% CI 1.60-1.86) and 1.37 (95% CI 1.33-1.44), respectively. BM frequency and subjective cognitive decline were significantly associated with the overall gut microbiome configuration (both p < 0.005) and specific microbial species in the 515 participants with microbiome data. Butyrate-producing microbial species were depleted in those with less frequent BM and worse cognition, whereas a higher abundance of proinflammatory species was associated with BM frequency of ≥twice/day and worse cognition.

DISCUSSION

Lower BM frequency was associated with worse cognitive function. The gut microbial dysbiosis may be a mechanistic link underlying the association.

Gut-brain connections in neurodegenerative disease: immunotherapeutic targeting of Bin1 in inflammatory bowel disease and Alzheimer's disease

Longer lifespan produces risks of age-associated neurodegenerative disorders such as Alzheimer's disease (AD), which is characterized by declines in memory and cognitive function. The pathogenic causes of AD are thought to reflect a progressive aggregation in the brain of amyloid plaques composed of beta-amyloid (Aß) peptides and neurofibrillary tangles composed of phosphorylated tau protein. Recently, long-standing investigations of the Aß disease hypothesis gained support via a passive immunotherapy targeting soluble Aß protein. Tau-targeting approaches using antibodies are also being pursued as a therapeutic approach to AD. In genome-wide association studies, the disease modifier gene Bin1 has been identified as a top risk factor for late-onset AD in human populations, with recent studies suggesting that Bin1 binds tau and influences its extracellular deposition. Interestingly, before AD emerges in the brain, tau levels rise in the colon, where Bin1-a modifier of tissue barrier function and inflammation-acts to promote inflammatory bowel disease (IBD). This connection is provocative given clinical evidence of gut-brain communication in age-associated neurodegenerative disorders, including AD. In this review, we discuss a Bin1-targeting passive immunotherapy developed in our laboratory to treat IBD that may offer a strategy to indirectly reduce tau deposition and limit AD onset or progression.