Is metabolic-healthy obesity associated with risk of dementia? An age-stratified analysis of the Whitehall II cohort study

BACKGROUND

Metabolically healthy obesity is hypothesized to be a benign condition but whether this is the case for dementia remains debated. We examined the role of age at assessment of metabolic-obesity phenotypes in associations with incident dementia.

METHODS

Obesity (body mass index ≥ 30 kg/m2) and poor metabolic health (≥ 2 of elevated serum triglycerides, low HDL-C, elevated blood pressure, and elevated serum fasting glucose) were used to define four metabolic-obesity phenotypes (metabolically healthy (MHNO) and unhealthy non-obesity (MUNO), metabolically healthy (MHO) and unhealthy obesity (MUO)) at < 60, 60 to < 70, and ≥ 70 years using 6 waves of data from the Whitehall II study and their associations with incident dementia was examined using Cox regression.

RESULTS

Analyses with exposures measured < 60, 60 to < 70, and ≥ 70 years involved 410 (5.8%), 379 (5.6%), and 262 (7.4%) incident dementia cases over a median follow-up of 20.8, 10.3, and 4.2 years respectively. In analyses of individual components, obesity before 60 years (HR 1.41, 95% CI: [1.08, 1.85]) but not at older ages was associated with dementia; unhealthy metabolic status when present < 60 years (HR 1.33, 95% CI: [1.08, 1.62]) and 60 to < 70 years (HR 1.32, 95% CI: [1.07, 1.62]) was associated with dementia. Compared to the metabolically healthy non-obesity group, the risk of dementia was higher in those with metabolically healthy obesity before 60 years (1.69; 95% CI: [1.16, 2.45]); this was not the case when metabolic-obesity phenotype was present at 60 to < 70 years or ≥ 70 years. Analyses at older ages were on smaller numbers due to death and drop-out but inverse probability weighting to account for missing data yielded similar results.

CONCLUSIONS

Individuals with metabolically healthy obesity before age 60 had a higher risk of incident dementia over a 27-year follow-up; the excess risk dissipates when metabolic health and obesity are measured after 70 years.

Circulating serum metabolites as predictors of dementia: a machine learning approach in a 21-year follow-up of the Whitehall II cohort study

BACKGROUND

Age is the strongest risk factor for dementia and there is considerable interest in identifying scalable, blood-based biomarkers in predicting dementia. We examined the role of midlife serum metabolites using a machine learning approach and determined whether the selected metabolites improved prediction accuracy beyond the effect of age.

METHODS

Five thousand three hundred seventy-four participants from the Whitehall II study, mean age 55.8 (standard deviation (SD) 6.0) years in 1997-1999 when 233 metabolites were quantified using nuclear magnetic resonance metabolomics. Participants were followed for a median 21.0 (IQR 20.4, 21.7) years for clinically-diagnosed dementia (N=329). Elastic net penalized Cox regression with 100 repetitions of nested cross-validation was used to select models that improved prediction accuracy for incident dementia compared to an age-only model. Risk scores reflecting the frequency with which predictors appeared in the selected models were constructed, and their predictive accuracy was examined using Royston's R², Akaike's information criterion, sensitivity, specificity, C-statistic and calibration.

RESULTS

Sixteen of the 100 models had a better c-statistic compared to an age-only model and 15 metabolites were selected at least once in all 16 models with glucose present in all models. Five risk scores, reflecting the frequency of selection of metabolites, and a 1-SD increment in all five risk scores was associated with higher dementia risk (HR between 3.13 and 3.26). Three of these, constituted of 4, 5 and 15 metabolites, had better prediction accuracy (c-statistic from 0.788 to 0.796) compared to an age-only model (c-statistic 0.780), all p<0.05.

CONCLUSIONS

Although there was robust evidence for the role of glucose in dementia, metabolites measured in midlife made only a modest contribution to dementia prediction once age was taken into account.

Association of Metabolic Syndrome With Incident Dementia: Role of Number and Age at Measurement of Components in a 28-Year Follow-up of the Whitehall II Cohort Study

OBJECTIVE

Previous research suggests an inconsistent association between Metabolic syndrome (MetS) and incident dementia. We examined the role of number of MetS components and age at their assessment for incident dementia.

RESEARCH DESIGN AND METHODS

MetS components (fasting glucose, triglycerides, waist circumference, blood pressure, and HDL cholesterol) on 7,265, 6,660, and 3,608 participants at <60, 60 to <70, and ≥70 years of age were used to examine associations with incident dementia using cause-specific Cox regression.

RESULTS

Analyses of MetS measured at <60, 60 to <70, and ≥70 years involved 393 (5.4%), 497 (7.5%), and 284 (7.9%) dementia cases over a median follow-up of 20.8, 10.4, and 4.2 years, respectively. Every additional MetS component before 60 (hazard ratio [HR] 1.13 [95% CI 1.05, 1.23]) and 60 to <70 (HR 1.08 [95% CI 1.00, 1.16]) but not ≥70 years (HR 1.04 [95% CI 0.96, 1.13]) was associated with higher dementia risk. MetS defined conventionally (≥3 components) before 60 years (HR 1.23 [95% CI 0.96, 1.57]), between 60 and 70 years (HR 1.14 [95% CI 0.91, 1.42]), or >70 years of age (HR 1.10 [95% CI 0.86, 1.40]) was not associated with incident dementia. Multistate models showed higher risk of dementia in those with ≥1 (HR 1.99 [95% CI 1.08, 3.66]) and ≥2 MetS components (HR 1.69 [95% CI 1.12, 2.56]) before 60 years of age, even when they remained free of cardiovascular disease over the follow-up.

CONCLUSIONS

Risk of incident dementia increases with every additional MetS component present in midlife rather than after accumulation of three components; only part of this risk is mediated by cardiovascular disease.

Association between kidney function and incidence of dementia: 10-year follow-up of the Whitehall II cohort study

BACKGROUND

Cognitive dysfunction is common in haemodialysis patients but whether poor kidney function in the general population is also associated with higher risk of dementia remains unclear.

OBJECTIVE

To examine the association of kidney function with incident dementia in community dwelling older adults.

DESIGN

Whitehall II prospective study.

SETTING

Population-based study on 6,050 adults, mean age 65.8 in 2007-2009.

METHODS

Poor kidney function, defined as estimated Glomerular Filtration Rate (eGFR) <60 ml/min/1.73 m2 in 2007-2009, and adverse change in eGFR was defined as decrease ≥4 ml/min/1.73 m2 between 2007-2009 and 2012-2013.Incident dementia was ascertained through linkage to electronic health records, and Cox regression was used to examine associations with dementia.

RESULTS

A total of 306 cases of dementia were recorded over a mean follow-up of 10 years. Baseline eGFR <60 was associated with a hazard ratio (HR) for dementia of 1.37 (95% CI 1.02, 1.85) in analysis adjusted for sociodemographic factors, hypertension, obesity, stroke, diabetes and cardiovascular disease/medication. Removing stroke cases at baseline and censoring them over the follow-up yielded an HR of 1.42 (95% CI 1.00, 2.00) for the association between CKD and dementia. Decline of eGFR ≥4 between 2007-2009 and 2012-2013 was associated with incidence of dementia over a 6.3 year mean follow-up (HR: 1.37; 95% CI 1.02, 1.85), with somewhat stronger associations when analyses were restricted to those with eGFR ≥60 in 2007-2009 (1.56; 95% CI: 1.12, 2.19).

CONCLUSION

Poor and declining kidney function in older adults is associated with a higher risk of dementia that is not attributable to stroke and persists after accounting for major cardiometabolic conditions.

Terminal decline in objective and self-reported measures of motor function before death: 10 year follow-up of Whitehall II cohort study

OBJECTIVES

To examine multiple objective and self-reported measures of motor function for their associations with mortality.

DESIGN

Prospective cohort study.

SETTING

UK based Whitehall II cohort study, which recruited participants aged 35-55 years in 1985-88; motor function component was added at the 2007-09 wave.

PARTICIPANTS

6194 participants with motor function measures in 2007-09 (mean age 65.6, SD 5.9), 2012-13, and 2015-16.

MAIN OUTCOME MEASURES

All cause mortality between 2007 and 2019 in relation to objective measures (walking speed, grip strength, and timed chair rises) and self-reported measures (physical component summary score of the SF-36 and limitations in basic and instrumental activities of daily living (ADL)) of motor function.

RESULTS

One sex specific standard deviation poorer motor function in 2007-09 (cases/total, 610/5645) was associated with an increased mortality risk of 22% (95% confidence interval 12% to 33%) for walking speed, 15% (6% to 25%) for grip strength, 14% (7% to 23%) for timed chair rises, and 17% (8% to 26%) for physical component summary score over a mean 10.6 year follow-up. Having basic/instrumental ADL limitations was associated with a 30% (7% to 58%) increased mortality risk. These associations were progressively stronger when measures were drawn from 2012-13 (mean follow-up 6.8 years) and 2015-16 (mean follow-up 3.7 years). Analysis of trajectories showed poorer motor function in decedents (n=484) than survivors (n=6194) up to 10 years before death for timed chair rises (standardised difference 0.35, 95% confidence interval 0.12 to 0.59; equivalent to a 1.2 (men) and 1.3 (women) second difference), nine years for walking speed (0.21, 0.05 to 0.36; 5.5 (men) and 5.3 (women) cm/s difference), six years for grip strength (0.10, 0.01 to 0.20; 0.9 (men) and 0.6 (women) kg difference), seven years for physical component summary score (0.15, 0.05 to 0.25; 1.2 (men) and 1.6 (women) score difference), and four years for basic/instrumental ADL limitations (prevalence difference 2%, 0% to 4%). These differences increased in the period leading to death for timed chair rises, physical component summary score, and ADL limitations.

CONCLUSION

Motor function in early old age has a robust association with mortality, with evidence of terminal decline emerging early in measures of overall motor function (timed chair rises and physical component summary score) and late in basic/instrumental ADL limitations.

Comparison of the predictive accuracy of multiple definitions of cognitive impairment for incident dementia: a 20-year follow-up of the Whitehall II cohort study

BACKGROUND

Studies generally use cognitive assessment done at one timepoint to define cognitive impairment in order to examine conversion to dementia. Our objective was to examine the predictive accuracy and conversion rate of seven alternate definitions of cognitive impairment for dementia.

METHODS

In this prospective study, we included participants from the Whitehall II cohort study who were assessed for cognitive impairment in 2007-09 and were followed up for clinically diagnosed dementia. Algorithms based on poor cognitive performance (defined using age-specific and sex-specific thresholds, and subsequently thresholds by education or occupation levels) and objective cognitive decline (using data from cognitive assessments in 1997-99, 2002-04, and 2007-09) were used to generate seven alternate definitions of cognitive impairment. We compared predictive accuracy using Royston's R 2, the Akaike information criterion (AIC), sensitivity, specificity, and Harrell's C-statistic.

FINDINGS

5687 participants, with a mean age of 65·7 years (SD 5·9) in 2007-09, were included and followed up for a median of 10·5 years (IQR 10·1-10·9). Over follow-up, 270 (4·7%) participants were clinically diagnosed with dementia. Cognitive impairment defined using both cognitive performance and decline had higher hazard ratios (from 5·08 [95% CI 3·82-6·76] to 5·48 [4·13-7·26]) for dementia than did definitions based on cognitive performance alone (from 3·25 [2·52-4·17] to 3·39 [2·64-4·36]) and cognitive decline alone (3·01 [2·37-3·82]). However, all definitions had poor predictive performance (C-statistic ranged from 0·591 [0·565-0·616] to 0·631 [0·601-0·660]), primarily due to low sensitivity (21·6-48·4%). A predictive model containing age, sex, and education without measures of cognitive impairment had better predictive performance (C-statistic 0·783 [0·758-0·809], sensitivity 74·2%, specificity 72·2%) than all seven definitions of cognitive impairment (all p<0·0001).

INTERPRETATION

These findings suggest that cognitive impairment in early old age might not be useful for dementia prediction, even when it is defined using longitudinal data on cognitive decline and thresholds of poor cognitive performance additionally defined by education or occupation.

FUNDING

National Institutes of Health, UK Medical Research Council.

Association Between Age at Diabetes Onset and Subsequent Risk of Dementia

IMPORTANCE

Trends in type 2 diabetes show an increase in prevalence along with younger age of onset. While vascular complications of early-onset type 2 diabetes are known, the associations with dementia remains unclear.

OBJECTIVE

To determine whether younger age at diabetes onset is more strongly associated with incidence of dementia.

DESIGN, SETTING, AND PARTICIPANTS

Population-based study in the UK, the Whitehall II prospective cohort study, established in 1985-1988, with clinical examinations in 1991-1993, 1997-1999, 2002-2004, 2007-2009, 2012-2013, and 2015-2016, and linkage to electronic health records until March 2019. The date of final follow-up was March 31, 2019.

EXPOSURES

Type 2 diabetes, defined as a fasting blood glucose level greater than or equal to 126 mg/dL at clinical examination, physician-diagnosed type 2 diabetes, use of diabetes medication, or hospital record of diabetes between 1985 and 2019.

MAIN OUTCOMES AND MEASURES

Incident dementia ascertained through linkage to electronic health records.

RESULTS

Among 10 095 participants (67.3% men; aged 35-55 years in 1985-1988), a total of 1710 cases of diabetes and 639 cases of dementia were recorded over a median follow-up of 31.7 years. Dementia rates per 1000 person-years were 8.9 in participants without diabetes at age 70 years, and rates were 10.0 per 1000 person-years for participants with diabetes onset up to 5 years earlier, 13.0 for 6 to 10 years earlier, and 18.3 for more than 10 years earlier. In multivariable-adjusted analyses, compared with participants without diabetes at age 70, the hazard ratio (HR) of dementia in participants with diabetes onset more than 10 years earlier was 2.12 (95% CI, 1.50-3.00), 1.49 (95% CI, 0.95-2.32) for diabetes onset 6 to 10 years earlier, and 1.11 (95% CI, 0.70-1.76) for diabetes onset 5 years earlier or less; linear trend test (P < .001) indicated a graded association between age at onset of type 2 diabetes and dementia. At age 70, every 5-year younger age at onset of type 2 diabetes was significantly associated with an HR of dementia of 1.24 (95% CI, 1.06-1.46) in analyses adjusted for sociodemographic factors, health behaviors, and health-related measures.

CONCLUSIONS AND RELEVANCE

In this longitudinal cohort study with a median follow-up of 31.7 years, younger age at onset of diabetes was significantly associated with higher risk of subsequent dementia.

Coffee consumption and risk of hearing impairment in men and women

BACKGROUND

Hearing loss is the fifth leading cause of disability in the world. Coffee consumption might have a beneficial effect on hearing function because of the antioxidant and anti-inflammatory properties of some of its compounds. However, no previous longitudinal study has assessed the association between coffee consumption and the risk of hearing impairment.

OBJECTIVE

To assess the prospective association between coffee consumption and risk of disabling hearing impairment in middle and older men and women from the UK Biobank study.

METHODS

Analytical cohort with 36,923 participants (16,142 men and 20,781 women) [mean (SD): 56.6 (7.8) years, 1.6 (1.4) cups/d, and -7.6 (1.3) dB for age, total coffee consumption and speech reception threshold in noise at baseline, respectively]. At baseline, coffee consumption was measured with 3-5 multiple-pass 24-h food records. Hearing function was measured with a digit triplet test, and disabling hearing impairment was defined as a speech reception threshold in noise > -3.5 dB in any physical exam during the follow-up. Analyses were stratified by sex and Cox regression models were used to assess the prospective association proposed.

RESULTS

Over 10 years of follow-up, 343 men and 345 women developed disabling hearing impairment. Among men, compared with those who consumed <1 cup/d of coffee, those who consumed 1, and ≥2 cups/d had a lower risk of hearing impairment (hazard ratio [95% confidence interval]: 0.72 [0.54-0.97] and 0.72 [0.56-0.92], respectively; P-trend: 0.01). This association was similar for caffeinated and decaffeinated coffee, and for filtered and non-filtered coffee, and was stronger in those with obesity (hazard ratio [95% confidence interval] for consumption of ≥2 vs. <1 cups/d: 0.39 [0.21-0.74]). No association was found between coffee and hearing function among women.

CONCLUSIONS

Coffee consumption was associated with lower risk of disabling hearing impairment in men but not in women. The association appeared to be independent of the coffee type and the preparation method.

High dephospho-uncarboxylated matrix Gla protein concentrations, a plasma biomarker of vitamin K, in relation to frailty: the Longitudinal Aging Study Amsterdam

PURPOSE

No previous study has evaluated the relationship between vitamin K and frailty. Thus, we assessed the relationship between vitamin K status and frailty over 13 years in the Longitudinal Aging Study Amsterdam (LASA).

METHODS

Prospective cohort study with 644 community-dwelling adults ≥ 55 years from the LASA cohort. In 2002-2003, plasma desphospho-uncarboxylated matrix Gla protein (dp-ucMGP) was measured as marker of vitamin K status through a sandwich ELISA. Frailty was measured at baseline and in four follow-up examinations with the LASA Frailty Index (LASA-FI), which was used as both a continuous and a dichotomous measure (FI ≥ 0.25), as indicator of the degree of frailty and frailty risk, respectively. Statistical analyses were performed with multivariable generalized estimating equations using the lowest dp-ucMGP tertile, reflecting a high vitamin K status, as reference.

RESULTS

The mean (SD) age was 59.9 (2.9) years, and 54% were female. Compared with the lowest tertile, the medium and highest dp-ucMGP tertile were associated with a higher degree of frailty [1.40, 95% confidence interval (0.01-2.81) and 1.62, (0.18-3.06), respectively. P trend: 0.03]. Additionally, the medium and highest dp-ucMGP tertile had a higher odds ratio of frailty [1.75 (1.11-2.77) and 1.63 (1.04-2.57), respectively]. The degree of frailty increased over time, but the differences by dp-ucMGP tertiles existed since baseline and remained stable during follow-up.

CONCLUSIONS

Baseline plasma low vitamin K status was associated with a greater degree of frailty and frailty risk in this cohort of older adults, which highlights the importance of ensuring an optimal nutritional status of this vitamin to prevent frailty in later life.

Dairy consumption and risk of falls in 2 European cohorts of older adults

BACKGROUND & AIMS

Some previous evidence have linked dairy products with greater muscle mass, bone mineral density and lower risk of osteoporosis. However, there is also evidence of a detrimental effect of milk on the risk of hip fracture. The aim of this study was to assess the prospective association between dairy consumption and risk of falls in older adults.

METHODS

We used data from 2 cohorts of community-dwellers aged ≥60y: the Seniors-ENRICA cohort with 2981 individuals, and the UK Biobank cohort with 8927 participants. In the Seniors-ENRICA, dairy consumption was assessed with a validated diet history in 2008-10, and falls were ascertained up to 2015. In the UK Biobank study, dairy consumption was obtained with 3-5 multiple-pass 24-h food records in 2006-10, and falls were assessed up to 2016.

RESULTS

A total of 801 individuals in the Seniors-ENRICA and 201 in the UK Biobank experienced ≥1 fall. After adjustment for potential confounders, dairy products were not associated with risk of falls in the Seniors-ENRICA [hazard ratio (95% confidence interval) per 1-serving increment in total dairy consumption: 1.02 (0.93-1.11), milk: 0.93 (0.85-1.01), yogurt: 1.05 (0.96-1.15), and cheese: 0.96 (0.88-1.05)]. Corresponding figures in the UK Biobank were: total dairy: 1.19 (1.00-1.41), milk: 1.53 (1.13-2.08), yogurt: 1.10 (0.90-1.31), and cheese: 1.02 (0.87-1.22).

CONCLUSIONS

These results suggest a null association between habitual dairy consumption and the risk of falling in older adults. Whether milk consumption may increase the risk of falls, as observed in the UK Biobank cohort, merits further study.

Habitual coffee consumption and risk of falls in 2 European cohorts of older adults

BACKGROUND

Habitual coffee consumption has been associated with lower risk of type 2 diabetes, cardiovascular disease, and sarcopenia, which are strong risk factors of falls. In addition, caffeine intake stimulates attention and vigilance, and reduces reaction time. Therefore, a protective effect of coffee on the risk of falling can be hypothesized.

OBJECTIVES

The aim of this study was to examine the association between habitual coffee consumption and the risk of ≥1 falls, injurious falls, and falls with fracture in older people.

METHODS

Data were taken from 2964 participants aged ≥60 y from the Seniors-ENRICA (Study on Nutrition and Cardiovascular Risk in Spain) cohort and 8999 participants aged ≥60 y from the UK Biobank cohort. In the Seniors-ENRICA study, habitual coffee consumption was assessed with a validated diet history in 2008-2010, and falls were ascertained up to 2015. In the UK Biobank study, coffee was measured with 3-5 multiple-pass 24-h food records starting in 2006, and falls were assessed up to 2016.

RESULTS

A total of 793 individuals in Seniors-ENRICA and 199 in UK Biobank experienced ≥1 fall during follow-up. After multivariable adjustment for major lifestyle and dietary risk factors and compared with daily consumption of <1 cup of coffee, the pooled HR for ≥1 fall was 0.75 (95% CI: 0.52, 1.07) for total coffee consumption of 1 cup/d and 0.74 (95% CI: 0.62, 0.90) for ≥2 cups/d (P-trend = 0.001). The corresponding figures for caffeinated coffee were 0.67 (95% CI: 0.42, 1.07) and 0.70 (95% CI: 0.56, 0.87) (P-trend < 0.001). Decaffeinated coffee was not associated with risk of falling in the analyzed cohorts. In Seniors-ENRICA, there was a tendency to lower risk of injurious falls among those consuming caffeinated coffee (HR: 0.83; 95% CI: 0.68, 1.00 for 1 cup/d; HR: 0.83; 95% CI: 0.64, 1.09 for ≥2 cups/d; P-trend = 0.09). No association was observed between caffeinated or decaffeinated coffee consumption and risk of falls with fracture.

CONCLUSIONS

Habitual coffee consumption was associated with lower risk of falling in older adults in Spain and the United Kingdom.

Coffee consumption and risk of physical function impairment, frailty and disability in older adults

PURPOSE

Habitual coffee consumption has been associated with lower risk of type 2 diabetes and cardiovascular disease. Since these diseases are main determinants of functional limitations, we have tested the hypothesis that coffee intake is associated with lower risk of physical function impairment, frailty and disability in older adults. We focused on women and those with obesity, hypertension or type 2 diabetes because they are at higher risk of functional limitations.

METHODS

Prospective study with 3289 individuals ≥ 60 years from the Seniors-ENRICA cohort. In 2008-2010 coffee consumption was measured through a validated dietary history. Participants were followed up until 2015 to ascertain incident impaired physical function, frailty and disability, assessed by both self-report and objective measures.

RESULTS

Compared with non-drinking coffee, consumption of ≥ 2 cups of coffee/day was associated with lower risk of impaired agility in women (hazard ratio [HR] 0.71, 95% confidence interval [CI] 0.51-0.97, P trend 0.04) and in those with obesity (HR 0.60; 95% CI 0.40-0.90, P trend 0.04). Intake of ≥ 2 cups of coffee/day was also linked to reduced risk of impaired mobility in women (HR 0.66; 95% CI 0.46-0.95, P trend 0.02) and among individuals with hypertension (HR 0.70, 95% CI 0.48-1.00, P trend 0.05). Moreover, among subjects with diabetes, those who consumed ≥ 2 cups/day had lower risk of disability in activities of daily living (HR 0.30, 95% CI 0.11-0.76, P trend 0.01).

CONCLUSIONS

In older people, habitual coffee consumption was not associated with increased risk of functional impairment, and it might even be beneficial in women and those with hypertension, obesity or diabetes.