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.

Objectively Measured Total Sedentary Time and Pattern of Sedentary Accumulation in Older Adults: Associations With Incident Cardiovascular Disease and All-Cause Mortality

BACKGROUND

We examined associations of total duration and pattern of accumulation of objectively measured sedentary behavior (SB) with incident cardiovascular disease (CVD) and all-cause mortality among older adults.

METHODS

Total sedentary time and 8 sedentary accumulation pattern metrics were extracted from accelerometer data of 3 991 Whitehall II study participants aged 60-83 years in 2012-2013. Incident CVD and all-cause mortality were ascertained up to March 2019.

RESULTS

Two hundred and ninety-nine CVD cases and 260 deaths were recorded over a mean (standard deviation [SD]) follow-up of 6.2 (1.3) and 6.4 (0.8) years, respectively. Adjusting for sociodemographic and behavioral factors, 1-SD (100.2 minutes) increase in total sedentary time was associated with 20% higher CVD risk (hazard ratio [95% confidence interval]: 1.20 [1.05-1.37]). More fragmented SB was associated with reduced CVD risk (eg, 0.86 [0.76-0.97] for 1-SD [6.2] increase in breaks per sedentary hour). Associations were not evident once health-related factors and moderate-to-vigorous physical activity (MVPA) were considered. For all-cause mortality, associations with more fragmented SB (eg, 0.73 [0.59-0.91] for breaks per sedentary hour) were found only among the youngest older group (<74 years; p for interaction with age < .01) independently from all covariates.

CONCLUSIONS

In this study, no associations of total sedentary time and sedentary accumulation patterns with incident CVD and all-cause mortality were found in the total sample once MVPA was considered. Our findings of reduced mortality risk with less total and more fragmented SB independent from MVPA among individuals <74 years need to be replicated to support the recent recommendations to reduce and fragment SB.

Importance of characterising sleep breaks within the 24-h movement behaviour framework

Accelerometers measure the acceleration of the body part they are attached and allow to estimate time spent in activity levels (sedentary behaviour, light, and moderate-to-vigorous physical activity) and sleep over a 24-h period for several consecutive days. These advantages come with the challenges to analyse the large amount of data while integrating dimensions of both physical activity/sedentary behaviour and sleep domains. This commentary raises the questions of 1) how to classify sleep breaks (i.e. wake after sleep onset) during the night within the 24-h movement behaviour framework and 2) how to assess their impact on health while also accounting for night time sleep duration and time in sedentary behaviour and physical activity during the day. The authors advocate for future collaborations between researchers from the physical activity/sedentary behaviour and sleep research fields to ensure appropriate analysis and interpretation of the tremendous amount of data recorded by the newer generation accelerometers. This is the only way forward to provide meaningfully accurate evidence to inform future 24-h movement behaviour guidelines.

Daily composition of movement behaviors with cardiovascular disease incidence in elderly

Background

Moderate-to-vigorous physical activity (MVPA) is proposed as key for cardiovascular diseases (CVD) prevention. At older ages, the role of sedentary behavior (SB) and light intensity physical activity (LIPA) remains unclear. Evidence so far is based on studies examining movement behaviors as independent entities ignoring their co-dependency. This study aims to examine the association between daily composition of objectively-assessed movement behaviors (MVPA, LIPA, SB) and incident CVD in older adults.

Methods

Whitehall II accelerometer sub-study participants free of CVD at baseline (N = 3319, 26.7% women, mean age=68.9 years in 2012-2013) wore a wrist-accelerometer from which times in SB, LIPA, and MVPA were extracted. Compositional Cox regression was used to estimate the hazard ratio (HR) for incident CVD for daily compositions of movement behaviors characterized by 10 (20 or 30) minutes greater duration in one movement behavior accompanied by decrease in another behavior, while keeping the third behavior constant, compared to reference composition.

Results

Of the 3319 participants, 299 had an incident CVD over a mean (SD) follow-up of 6.2 (1.3) years. Compared to individuals with daily movement behavior composition composed with MVPA at recommended 21 minutes per day (150 minutes/week), composition with additional 10 minutes of MVPA and 10 minutes less SB were associated with smaller risk reduction -8% (HR, 0.92; 95% CI, 0.87-0.99) - than the 14% increase in risk associated with a composition of similarly reduced time in MVPA and more time in SB (HR, 1.14; 95% CI, 1.02-1.27). For a given MVPA duration, the CVD risk did not differ as a function of LIPA and SB durations.

Conclusions

An increase in MVPA duration at the expense of time in either SB or LIPA was associated with lower risk of incident CVD. This study lends support to public health guidelines encouraging increase in MVPA or at least maintain MVPA at their current duration.

Key messages

Older adults should be encouraged to increase their moderate-to-vigorous physical activity or at least maintain at their current levels to lower risk of incident cardiovascular disease. Highly sedentary older adults should increase their moderate-to-vigorous physical activity by decreasing sedentary time rather than light-intensity activity to prevent cardiovascular disease.

Association of big-5 personality traits with cognitive impairment and dementia: a longitudinal study

BACKGROUND

Personality traits have been liked to cognitive outcomes such as dementia, but whether these associations are robust to the effects of third variables remains the subject of debate. We examined the role of socioeconomic status, depression (history and depressive symptoms), health behaviours and chronic conditions in the association of the big-5 personality traits with cognitive performance, cognitive impairment and incidence of dementia.

METHODS

Data on 6135 persons (30% women), aged 60-83 years in 2012/13, are drawn from the Whitehall II Study. Participants responded to the 26-item Midlife Development Inventory to assess personality traits (openness, conscientiousness, extraversion, agreeableness and neuroticism), underwent cognitive testing in 2012/13 and 2015/16 and were followed for incidence of dementia (N=231) until 2019.

RESULTS

Logistic regression, adjusted for sociodemographic factors, suggested a cross-sectional association with cognitive impairment for four of the five traits but only neuroticism was associated with incident cognitive impairment. All associations were completely attenuated when the analyses were adjusted for depression. Cox regression (mean follow-up: 6.18 years) adjusted for sociodemographic variables showed higher conscientiousness (HR per SD increment=0.72; 95% CI 0.65 to 0.81) and extraversion (HR=0.85; 95% CI 0.75 to 0.97) to be associated with lower dementia risk; higher neuroticism (HR=1.32; 95% CI 1.17 to 1.49) was associated with increased risk. Further adjustment for depression led to only conscientiousness retaining an association with dementia (HR=0.81; 95% CI 0.69 to 0.96), which was robust to adjustment for all covariates (HR=0.84; 95% CI 0.71 to 0.91; P=0.001).

CONCLUSION

Our results show that only conscientiousness has an association with incidence of dementia that is not attributable to socioeconomic status or depression. The association of neuroticism with dementia was explained by depression.