Sleep regularity and mortality: a prospective analysis in the UK Biobank.

Background: Irregular sleep-wake timing may cause circadian disruption leading to several chronic age-related diseases. We examined the relationship between sleep regularity and risk of all-cause, cardiovascular disease (CVD), and cancer mortality in 88,975 participants from the prospective UK Biobank cohort. Methods: The sleep regularity index (SRI) was calculated as the probability of an individual being in the same state (asleep or awake) at any two time points 24 hr apart, averaged over 7 days of accelerometry (range 0-100, with 100 being perfectly regular). The SRI was related to the risk of mortality in time-to-event models. Results: The mean sample age was 62 years (standard deviation [SD], 8), 56% were women, and the median SRI was 60 (SD, 10). There were 3010 deaths during a mean follow-up of 7.1 years. Following adjustments for demographic and clinical variables, we identified a non-linear relationship between the SRI and all-cause mortality hazard (p [global test of spline term]<0.001). Hazard ratios, relative to the median SRI, were 1.53 (95% confidence interval [CI]: 1.41, 1.66) for participants with SRI at the 5th percentile (SRI = 41) and 0.90 (95% CI: 0.81, 1.00) for those with SRI at the 95th percentile (SRI = 75), respectively. Findings for CVD mortality and cancer mortality followed a similar pattern. Conclusions: Irregular sleep-wake patterns are associated with higher mortality risk. Funding: National Health and Medical Research Council of Australia (GTN2009264; GTN1158384), National Institute on Aging (AG062531), Alzheimer's Association (2018-AARG-591358), and the Banting Fellowship Program (#454104).

Association Between Slow-Wave Sleep Loss and Incident Dementia.

Importance: Slow-wave sleep (SWS) supports the aging brain in many ways, including facilitating the glymphatic clearance of proteins that aggregate in Alzheimer disease. However, the role of SWS in the development of dementia remains equivocal. Objective: To determine whether SWS loss with aging is associated with the risk of incident dementia and examine whether Alzheimer disease genetic risk or hippocampal volumes suggestive of early neurodegeneration were associated with SWS loss. Design, Setting, and Participants: This prospective cohort study included participants in the Framingham Heart Study who completed 2 overnight polysomnography (PSG) studies in the time periods 1995 to 1998 and 2001 to 2003. Additional criteria for individuals in this study sample were an age of 60 years or older and no dementia at the time of the second overnight PSG. Data analysis was performed from January 2020 to August 2023. Exposure: Changes in SWS percentage measured across repeated overnight sleep studies over a mean of 5.2 years apart (range, 4.8-7.1 years). Main Outcome: Risk of incident all-cause dementia adjudicated over 17 years of follow-up from the second PSG. Results: From the 868 Framingham Heart Study participants who returned for a second PSG, this cohort included 346 participants with a mean age of 69 years (range, 60-87 years); 179 (52%) were female. Aging was associated with SWS loss across repeated overnight sleep studies (mean [SD] change, -0.6 [1.5%] per year; P < .001). Over the next 17 years of follow-up, there were 52 cases of incident dementia. In Cox regression models adjusted for age, sex, cohort, positivity for at least 1 APOE ε4 allele, smoking status, sleeping medication use, antidepressant use, and anxiolytic use, each percentage decrease in SWS per year was associated with a 27% increase in the risk of dementia (hazard ratio, 1.27; 95% CI, 1.06-1.54; P = .01). SWS loss with aging was accelerated in the presence of Alzheimer disease genetic risk (ie, APOE ε4 allele) but not hippocampal volumes measured proximal to the first PSG. Conclusions and Relevance: This cohort study found that slow-wave sleep percentage declined with aging and Alzheimer disease genetic risk, with greater reductions associated with the risk of incident dementia. These findings suggest that SWS loss may be a modifiable dementia risk factor.

Sleep Regularity and Mortality: A Prospective Analysis in the UK Biobank.

Background: Irregular sleep-wake timing may cause circadian disruption leading to several chronic age-related diseases. We examined the relationship between sleep regularity and risk of all-cause, cardiovascular disease (CVD), and cancer mortality in 88,975 participants from the prospective UK Biobank cohort. Methods: The sleep regularity index (SRI) was calculated as the probability of an individual being in the same state (asleep or awake) at any two time points 24 hours apart, averaged over 7-days of accelerometry (range 0-100, with 100 being perfectly regular). The SRI was related to the risk of mortality in time-to-event models. Findings: The mean sample age was 62 years (SD, 8), 56% were women, and the median SRI was 60 (SD, 10). There were 3010 deaths during a mean follow-up of 7.1 years. Following adjustments for demographic and clinical variables, we identified a non-linear relationship between the SRI and all-cause mortality hazard (p [global test of spline term] < 0·001). Hazard Ratios, relative to the median SRI, were 1·53 (95% confidence interval [CI]: 1·41, 1·66) for participants with SRI at the 5th percentile (SRI = 41) and 0·90 (95% CI: 0·81, 1·00) for those with SRI at the 95th percentile (SRI = 75), respectively. Findings for CVD mortality and cancer mortality followed a similar pattern. Conclusions: Irregular sleep-wake patterns are associated with higher mortality risk. Funding: National Health and Medical Research Council of Australia (GTN2009264; GTN1158384), National Institute on Aging (AG062531), Alzheimer's Association (2018-AARG-591358), and the Banting Fellowship Program (#454104).

Lighter sleep is associated with higher enlarged perivascular spaces burden in middle-aged and elderly individuals.

BACKGROUND: While healthy sleep is suggested to promote glymphatic clearance in the brain, poorer sleep may be associated with higher enlarged perivascular spaces (ePVS) burden, potentially representing impaired perivascular drainage. This study aims to evaluate the association between ePVS burden and polysomnographic sleep characteristics in a large community-based sample. METHODS: 552 dementia and stroke-free Framingham Heart Study participants (age: 58.6 ± 8.9 years; 50.4% men) underwent a full-night in-home polysomnography. Three years later on average, participants underwent a brain MRI. ePVS were rated in the basal ganglia and centrum semiovale, and dichotomized as low burden (<20 counts, grades 1 and 2) or high burden (>20 counts, grades 3 and 4). Logistic regression analyses relating sleep variables to subsequent ePVS burden were used, adjusted for age, sex, time interval between polysomnography and MRI, ApoE ε4 allele carrier status, hypertension, and smoking. RESULTS: Longer N1 sleep and shorter N3 sleep duration were associated with higher ePVS burden in the centrum semiovale. When stratifying these associations by subpopulations, longer N1 sleep duration with ePVS burden was observed especially in older individuals and hypertensive participants. Associations between ePVS burden and other sleep characteristics such as total sleep time and REM sleep duration varied according to ApoE ε4 allele carrier status. CONCLUSIONS: Lighter sleep, as characterized by longer N1 sleep and shorter slow-wave sleep, is associated with higher ePVS burden. These findings suggest that sleep architecture may be involved in glymphatic clearance and cerebral small vessel disease, which could be an important biological link between sleep and dementia risk.

Cardiovascular Risk Associated with Poorer Memory in Middle-Aged Adults from the Healthy Brain Project.

BACKGROUND: Midlife cardiovascular risk factors (CVRF) are associated with reduced cognition and an increased risk of dementia. OBJECTIVE: To further investigate this association using remote unsupervised online assessment of cognition and cardiovascular risk in middle-aged adults; and to explore the extent to which the association is altered by carriage of the APOE ɛ4 allele. METHODS: The Healthy Brain Project is an online cohort of middle-aged cognitively unimpaired adults (40-70 years) who have undergone cognitive assessment and provided self-reports of demographic and health history. Cardiovascular risk was determined by ascertaining history of hypertension, hypercholesterolemia, diabetes mellitus, overweight (body mass index≥25), and current cigarette smoking. Participants (n = 2,480) were then grouped based on the number of reported CVRF into no CVRF, 1, 2, and≥3 CVRF. Associations between the number of CVRF as a continuous variable, CVRF group, and each individual CVRF with composite measures of attention, memory and subjective cognitive function were investigated. RESULTS: Higher number of CVRF was associated with poorer attention (ß= -0.042, p = 0.039) and memory (ß= -0.080, p < 0.001), but not with subjective cognitive function. When considered individually, current smoking (ß= -0.400, p = 0.015), diabetes (ß= -0.251, p = 0.023), and hypercholesterolemia (ß= -0.109, p = 0.044) were independently associated with poorer memory performance. APOE ɛ4 carriers with≥1 CVRF performed worse on memory than ɛ4 carriers with no CVRFs (ß(SE) = 0.259(0.077), p = 0.004). This was not observed in ɛ4 non-carriers. CONCLUSION: In cognitively normal middle-aged adults, CVRF were associated with poorer cognition, particularly in the memory domain. These results support feasibility of online assessment of cardiovascular risk for cognitive impairment.

Higher habitual dietary flavonoid intake associates with lower central blood pressure and arterial stiffness in healthy older adults.

Flavonoids have shown anti-hypertensive and anti-atherosclerotic properties: the impact of habitual flavonoid intake on vascular function, central haemodynamics and arterial stiffness may be important. We investigated the relationship between habitual flavonoid consumption and measures of central blood pressure and arterial stiffness. We performed cross-sectional analysis of 381 non-smoking healthy older adults (mean age 66·0 (sd 4·1) years; BMI, 26·4 (sd 4·41) kg/m2; 41 % male) recruited as part of the Australian Research Council Longevity Intervention study. Flavonoid intake (i.e. flavonols, flavones, flavanones, anthocyanins, isoflavones, flavan-3-ol monomers, proanthocyanidins, theaflavins/thearubigins and total consumption) was estimated from FFQ using the US Department of Agriculture food composition databases. Measures of central haemodynamics and arterial stiffness included systolic blood pressure (cSBP), diastolic blood pressure (cDBP), mean arterial pressure (cMAP) and augmentation index (cAIx). After adjusting for demographic and lifestyle confounders, each sd/d higher intake of anthocyanins ((sd 44·3) mg/d) was associated with significantly lower cDBP (-1·56 mmHg, 95 % CI -2·65, -0·48) and cMAP (-1·62 mmHg, 95 % CI -2·82, -0·41). Similarly, each sd/d higher intake of flavanones ((sd 19·5) mg/d) was associated with ~1 % lower cAIx (-0·93 %, 95 % CI -1·77, -0·09). These associations remained significant after additional adjustment for (1) a dietary quality score and (2) other major nutrients that may affect blood pressure or arterial stiffness (i.e. Na, K, Ca, Mg, n-3, total protein and fibre). This study suggests a possible benefit of dietary anthocyanin and flavanone intake on central haemodynamics and arterial stiffness; these findings require corroboration in further research.

Interleukin-6 Interacts with Sleep Apnea Severity when Predicting Incident Alzheimer's Disease Dementia.

Because of their roles as potential risk factors, we evaluated whether obstructive sleep apnea (OSA) severity interacts with interleukin-6 (IL-6) in predicting incident dementia of the Alzheimer's type (DAT). In 269 dementia-free participants, IL-6 and the apnea-hypopnea index (AHI) were measured at baseline and incident DAT was surveilled for up to 22.8 years. Cox models revealed a significant interaction: In the lowest IL-6 quartile only, a higher AHI was associated with an elevated risk of DAT. The association between OSA severity and incident DAT might be especially apparent in the absence of inflammation or absence of potential benefits from IL-6.

Circulating fibroblast growth factor 23 levels and incident dementia: The Framingham heart study.

BACKGROUND: Fibroblast growth factor 23 is an emerging vascular biomarker, recently associated with cerebral small vessel disease and poor cognition in patients on dialysis. It also interacts with klotho, an anti-aging and cognition enhancing protein. OBJECTIVE: To determine if circulating Fibroblast growth factor 23 (FGF23) is associated with new-onset cognitive outcomes in a community-based cohort of cognitively healthy adults with long-term follow-up. METHODS: We measured serum FGF23 levels in 1537 [53% women, mean age 68.7 (SD 5.7)] dementia-free Framingham Offspring participants at their 7th quadrennial examination (1998-2001), and followed these participants for the development of clinical all-cause dementia and Alzheimer's disease (AD). Secondary outcomes included MRI-based structural brain measures, and neurocognitive test performance at exam 7. RESULTS: During a median (Q1, Q3) 12-year (7.0, 13.3) follow up, 122 (7.9%) participants developed dementia, of whom 91 (5.9%) had AD. Proportional-hazards regression analysis, adjusted for age, sex, education, systolic blood pressure, antihypertensive medication, prevalent cardiovascular disease, diabetes mellitus, smoking status and apoE ε4 carrier status, revealed that higher serum FGF23 levels were associated with an increased risk of incident dementia and AD (Hazard ratio [HR] per 1 standard deviation increment in inverse transformed FGF23 level 1.25, 95% CI 1.02-1.53, and 1.32, 95% CI 1.04-1.69, respectively). There was no significant interaction according to presence/absence of significant renal impairment (eGFR <30 versus ≥30ml/min) and risk of dementia (based on 1537; p = 0.97). CONCLUSIONS: Higher circulating FGF23 is associated with an increased risk of dementia, suggesting that FGF23-related biological pathways may play a role in the development of dementia.

Sugar- and Artificially Sweetened Beverages and the Risks of Incident Stroke and Dementia: A Prospective Cohort Study.

BACKGROUND AND PURPOSE: Sugar- and artificially-sweetened beverage intake have been linked to cardiometabolic risk factors, which increase the risk of cerebrovascular disease and dementia. We examined whether sugar- or artificially sweetened beverage consumption was associated with the prospective risks of incident stroke or dementia in the community-based Framingham Heart Study Offspring cohort. METHODS: We studied 2888 participants aged >45 years for incident stroke (mean age 62 [SD, 9] years; 45% men) and 1484 participants aged >60 years for incident dementia (mean age 69 [SD, 6] years; 46% men). Beverage intake was quantified using a food-frequency questionnaire at cohort examinations 5 (1991-1995), 6 (1995-1998), and 7 (1998-2001). We quantified recent consumption at examination 7 and cumulative consumption by averaging across examinations. Surveillance for incident events commenced at examination 7 and continued for 10 years. We observed 97 cases of incident stroke (82 ischemic) and 81 cases of incident dementia (63 consistent with Alzheimer's disease). RESULTS: After adjustments for age, sex, education (for analysis of dementia), caloric intake, diet quality, physical activity, and smoking, higher recent and higher cumulative intake of artificially sweetened soft drinks were associated with an increased risk of ischemic stroke, all-cause dementia, and Alzheimer's disease dementia. When comparing daily cumulative intake to 0 per week (reference), the hazard ratios were 2.96 (95% confidence interval, 1.26-6.97) for ischemic stroke and 2.89 (95% confidence interval, 1.18-7.07) for Alzheimer's disease. Sugar-sweetened beverages were not associated with stroke or dementia. CONCLUSIONS: Artificially sweetened soft drink consumption was associated with a higher risk of stroke and dementia.

Randomized controlled trial examining the effects of fish oil and multivitamin supplementation on the incorporation of n-3 and n-6 fatty acids into red blood cells.

The present randomized, placebo-controlled, double-blind, parallel-groups clinical trial examined the effects of fish oil and multivitamin supplementation on the incorporation of n-3 and n-6 fatty acids into red blood cells. Healthy adult humans (n = 160) were randomized to receive 6 g of fish oil, 6 g of fish oil plus a multivitamin, 3 g of fish oil plus a multivitamin or a placebo daily for 16 weeks. Treatment with 6 g of fish oil, with or without a daily multivitamin, led to higher eicosapentaenoic acid (EPA) composition at endpoint. Docosahexaenoic acid (DHA) composition was unchanged following treatment. The long chain LC n-3 PUFA index was only higher, compared to placebo, in the group receiving the combination of 6 g of fish oil and the multivitamin. Analysis by gender revealed that all treatments increased EPA incorporation in females while, in males, EPA was only significantly increased by the 6 g fish oil multivitamin combination. There was considerable individual variability in the red blood cell incorporation of EPA and DHA at endpoint. Gender contributed to a large proportion of this variability with females generally showing higher LC n-3 PUFA composition at endpoint. In conclusion, the incorporation of LC n-3 PUFA into red blood cells was influenced by dosage, the concurrent intake of vitamin/minerals and gender.

Cocoa polyphenols enhance positive mood states but not cognitive performance: a randomized, placebo-controlled trial.

This study aimed to examine the acute and sub-chronic effects of cocoa polyphenols on cognition and mood. In a randomized, double-blind study, healthy middle-aged participants received a dark chocolate drink mix standardized to contain 500 mg, 250 mg or 0 mg of polyphenols (placebo) in a parallel-groups design. Participants consumed their assigned treatment once daily for 30 days. Cognition was measured with the Cognitive Drug Research system and self-rated mood with the Bond-Lader Visual Analogue Scale. Participants were tested at baseline, at 1, 2.5 and 4 h after a single acute dose and again after receiving 30 days of treatment. In total, 72 participants completed the trial. After 30 days, the high dose of treatment significantly increased self-rated calmness and contentedness relative to placebo. Mood was unchanged by treatment acutely while cognition was unaffected by treatment at all time points. This randomized controlled trial is perhaps the first to demonstrate the positive effects of cocoa polyphenols on mood in healthy participants. This provides a rationale for exploring whether cocoa polyphenols can ameliorate the symptoms associated with clinical anxiety or depression.

Multivitamin-multimineral supplementation and mortality: a meta-analysis of randomized controlled trials.

BACKGROUND: Multivitamins are the most commonly used supplement in the developed world. Recent epidemiologic findings suggest that multivitamin use increases the risk of mortality. OBJECTIVE: We aimed to determine whether multivitamin-multimineral treatment, used for primary or secondary prevention, increases the risk of mortality in independently living adults. DESIGN: We performed a meta-analysis of randomized controlled trials. Multiple electronic databases were systematically searched from March to October 2012. Randomized controlled primary or secondary prevention trials were considered for inclusion. Eligible trials investigated daily multivitamin-multimineral supplementation for ≥1 y. Cohorts described as institutionalized or as having terminal illness (tertiary prevention) were excluded. The number of deaths and the sample size of each study arm were extracted independently by 2 researchers. Twenty-one articles were included in the analysis, which generated a total pooled sample of 91,074 people and 8794 deaths. These trials were pooled in a meta-analysis, and the outcomes were expressed as RRs and 95% CIs. RESULTS: The average age of the pooled sample was 62 y, and the average duration of supplementation was 43 mo. Across all studies, no effect of multivitamin-multimineral treatment on all-cause mortality (RR: 0.98; 95% CI: 0.94, 1.02) was observed. There was a trend for a reduced risk of all-cause mortality across primary prevention trials (RR: 0.94; 95% CI: 0.89, 1.00). Multivitamin-multimineral treatment had no effect on mortality due to vascular causes (RR: 1.01; 95% CI: 0.93, 1.09) or cancer (RR: 0.96; 95% CI: 0.88, 1.04). No statistical evidence of heterogeneity or publication bias was observed. CONCLUSION: Multivitamin-multimineral treatment has no effect on mortality risk.

Do long-chain n-3 fatty acids reduce arterial stiffness? A meta-analysis of randomised controlled trials.

Fish oils, rich in long-chain n-3 PUFA, are known to reduce various risk factors for CVD. However, conclusive evidence regarding the benefits of n-3 on arterial stiffness, a risk factor for CVD, has not yet been established. Consequently, we conducted the first study aimed to quantify the effects of n-3 supplementation on arterial stiffness through meta-analysis. Multiple databases and clinical trial registries were systematically searched up until September 2010 for randomised and controlled adult human clinical trials to investigate the effects of long-chain n-3 fatty acids on arterial stiffness. No limits were set on dosage sizes or sample characteristics. A total of ten n-3 trials met the final inclusion criteria; four using pulse wave velocity (PWV) and six using arterial compliance, measured as capacitive compliance or systemic arterial compliance, as respective outcome measures. Meta-analysis revealed that n-3 was statistically significant in effectively improving both PWV (g = 0·33; 95 % CI 0·12, 0·56; P < 0·01) and arterial compliance (g = 0·48; 95 % CI 0·24, 0·72; P < 0·001). There was no evidence of heterogeneity or publication bias. Results were not influenced by changes in blood pressure, heart rate or BMI. The findings of the present study reveal that supplementation with n-3 offers a scientifically supported means of reducing arterial stiffness. Reduction in arterial stiffness by n-3 may account for some of its purported cardioprotective effects.

Healthy middle-aged individuals are vulnerable to cognitive deficits as a result of increased arterial stiffness.

OBJECTIVES: Whilst pulse pressure and pulse wave velocity have been shown to predict cognitive outcomes, the relationship between arterial stiffness and cognition has not yet been explored in an entirely healthy nonclinical population. Furthermore, the effects of arterial stiffness on cognition are yet to be examined with computerized cognitive test batteries sensitive to subtle differences in cognitive performance. The aim of the present study was to examine the relationship between arterial stiffness (pulse pressure and augmentation index) and specific domains of cognitive performance in a healthy middle-aged sample. INDIVIDUALS AND METHOD: The sample comprised 92 healthy individuals, aged between 40 and 65 years, with no history of cardiovascular disease, diabetes, stroke, hypertension, smoking and were free from medication. The cognitive drug research (CDR) computerized system was implemented to assess domains of cognitive performance, whereas pulse pressure and augmentation index were determined centrally by a noninvasive SphygmoCor device. RESULTS: Pulse pressure was an independent predictor of both episodic secondary memory performance (beta = -0.27, R change = 0.07, P < 0.05) and speed of memory retrieval (beta = 0.24, R change = 0.06, P < 0.05). Augmentation index was also an independent predictor of speed of memory (beta = 0.27, R change = 0.07, P < 0.01). Working memory, power of attention and continuity of attention were not predicted by pulse pressure or augmentation index. CONCLUSION: It was concluded that healthy middle-aged adults are vulnerable to memory deficits as a result of normal increases in pulse pressure associated with ageing.