Associations between sporting physical activity and cognition in mid and later-life: Evidence from two cohorts

Evidence has linked sporting leisure time physical activity (sporting-LTPA) to healthy cognition throughout adulthood. This may be due to the physiological effects of physical activity (PA), or to other, psychosocial facets of sport. We examined associations between sporting-LTPA and cognition while adjusting for device-measured PA volume devoid of context, both in midlife (N = 4041) participants from the 1970 British Cohort Study and later-life (N = 957) participants from the British Regional Heart Study. Independent of device-measured PA, we identified positive associations between sporting-LTPA and cognition. Sports with team/partner elements were strongly positively associated with cognition, suggesting LTPA context may be critical to this relationship.

Comparison of variance estimators for meta-analysis of instrumental variable estimates

Background: Mendelian randomization studies perform instrumental variable (IV) analysis using genetic IVs. Results of individual Mendelian randomization studies can be pooled through meta-analysis. We explored how different variance estimators influence the meta-analysed IV estimate.

Methods: Two versions of the delta method (IV before or after pooling), four bootstrap estimators, a jack-knife estimator and a heteroscedasticity-consistent (HC) variance estimator were compared using simulation. Two types of meta-analyses were compared, a two-stage meta-analysis pooling results, and a one-stage meta-analysis pooling datasets.

Results: Using a two-stage meta-analysis, coverage of the point estimate using bootstrapped estimators deviated from nominal levels at weak instrument settings and/or outcome probabilities ≤ 0.10. The jack-knife estimator was the least biased resampling method, the HC estimator often failed at outcome probabilities ≤ 0.50 and overall the delta method estimators were the least biased. In the presence of between-study heterogeneity, the delta method before meta-analysis performed best. Using a one-stage meta-analysis all methods performed equally well and better than two-stage meta-analysis of greater or equal size.

Conclusions: In the presence of between-study heterogeneity, two-stage meta-analyses should preferentially use the delta method before meta-analysis. Weak instrument bias can be reduced by performing a one-stage meta-analysis.

Prospective study of circulating soluble CD40 ligand concentrations and the incidence of cardiovascular disease in a nested prospective case-control study of older men and women

BACKGROUND

CD40 ligand(CD40L) is implicated in atherosclerotic plaque formation.

OBJECTIVES

We investigated prospective associations between circulating soluble CD40L and myocardial infraction (MI) or stroke in an older general population cohort, accounting for established and novel cardiovascular risk factors.

METHODS

Baseline serum CD40L (sCD40L) was measured in incident MI (n = 368) and stroke (n = 304) cases and two controls per case, 'nested' in prospective UK studies of 4252 men and 4286 women aged 60-79 years, sampled from general practices in Britain in 1998-2000, with 7-year follow-up for fatal and non-fatal MI and stroke.

RESULTS

sCD40L was higher in smokers and negatively associated with lung function and positively associated with total cholesterol and markers of inflammation, but not with other established cardiovascular disease (CVD) risk factors. Geometric mean sCD40L levels did not differ between MI cases and controls (5.94 ng mL(-1) vs. 5.82 ng mL(-1); P = 0.5) or between stroke cases and controls (5.61 ng mL(-1) vs. 5.28 ng mL(-1), P = 0.1). There was no strong evidence for elevated risk of MI or stroke in multivariable models comparing participants in the top to those in the bottom third of sCD40L. Age-adjusted odds ratios (ORs) were 1.39 [95% confidence interval (CI) 0.98, 1.96] for MI and 1.16 (0.78, 1.73) for stroke. These attenuated to 1.24 (95% CI 0.86, 1.79) and 1.18 (0.78, 1.78), respectively, after adjustment for established and novel CVD risk factors.

CONCLUSIONS

sCD40L is associated with other inflammatory markers but is not itself a strong independent risk marker for either stroke or MI.

Prospective study of circulating soluble CD40 ligand concentrations and the incidence of cardiovascular disease in a nested prospective case-control study of older men and women

BACKGROUND

CD40 ligand(CD40L) is implicated in atherosclerotic plaque formation.

OBJECTIVES

We investigated prospective associations between circulating soluble CD40L and myocardial infraction (MI) or stroke in an older general population cohort, accounting for established and novel cardiovascular risk factors.

METHODS

Baseline serum CD40L (sCD40L) was measured in incident MI (n = 368) and stroke (n = 304) cases and two controls per case, 'nested' in prospective UK studies of 4252 men and 4286 women aged 60-79 years, sampled from general practices in Britain in 1998-2000, with 7-year follow-up for fatal and non-fatal MI and stroke.

RESULTS

sCD40L was higher in smokers and negatively associated with lung function and positively associated with total cholesterol and markers of inflammation, but not with other established cardiovascular disease (CVD) risk factors. Geometric mean sCD40L levels did not differ between MI cases and controls (5.94 ng mL(-1) vs. 5.82 ng mL(-1); P = 0.5) or between stroke cases and controls (5.61 ng mL(-1) vs. 5.28 ng mL(-1), P = 0.1). There was no strong evidence for elevated risk of MI or stroke in multivariable models comparing participants in the top to those in the bottom third of sCD40L. Age-adjusted odds ratios (ORs) were 1.39 [95% confidence interval (CI) 0.98, 1.96] for MI and 1.16 (0.78, 1.73) for stroke. These attenuated to 1.24 (95% CI 0.86, 1.79) and 1.18 (0.78, 1.78), respectively, after adjustment for established and novel CVD risk factors.

CONCLUSIONS

sCD40L is associated with other inflammatory markers but is not itself a strong independent risk marker for either stroke or MI.

Cotinine-assessed second-hand smoke exposure and risk of cardiovascular disease in older adults

Objectives

To examine whether second-hand smoke (SHS) exposure measured by serum cotinine is associated with increased coronary heart disease (CHD) and stroke risk among contemporary older British adults.

Design

Prospective population-based study with self-reported medical history and health behaviours. Fasting blood samples were analysed for serum cotinine and cardiovascular disease (CVD) risk markers.

Setting

Primary care centres in 25 British towns in 1998–2001.

Patients

8512 60–79-year-old men and women selected from primary care registers.

Main outcome measures

Fatal and non-fatal myocardial infarction (MI; n=445) and stroke (n=386) during median 7.8-year follow-up.

Main exposure

Observational study of serum cotinine assayed from fasting blood sample using liquid chromatography tandem mass spectrometry method, and self-reported smoking history.

Results

Among 5374 non-smokers without pre-existing CVD, geometric mean cotinine was 0.15 ng/ml (IQR 0.05–0.30). Compared with non-smokers with cotinine ≤0.05 ng/ml, higher cotinine levels (0.06–0.19, 0.2–0.7 and 0.71–15.0 ng/ml) showed little association with MI; adjusted HRs were 0.92 (95% CI 0.63 to 1.35), 1.07 (0.73 to 1.55) and 1.09 (0.69 to 1.72), p(trend)=0.69. Equivalent HRs for stroke were 0.82 (0.55 to 1.23), 0.74 (0.48 to 1.13) and 0.69 (0.41 to 1.17), p(trend)=0.065. The adjustment for sociodemographic, behavioural and CVD risk factors had little effect on the results. The HR of MI for smokers (1–9 cigarettes/day) compared with non-smokers with cotinine ≤0.05 ng/ml was 2.14 (1.39 to 3.52) and 1.03 (0.52 to 2.04) for stroke.

Conclusions

In contemporary older men and women, SHS exposure (predominantly at low levels) was not related to CHD or stroke risks, but we cannot rule out the possibility of modest effects at higher exposure levels.

Secondhand smoke (SHS) exposure is associated with circulating markers of inflammation and endothelial function in adult men and women

AIMS

Secondhand smoke (SHS) exposure is associated with elevated CHD risks. Yet the pathways through which this may operate have not been investigated in epidemiologic studies with objective SHS exposure measures and a wide range of CHD risk factors associated with active smoking. Therefore we investigate associations between SHS exposure and CHD risk factors, to clarify how SHS exposure may raise risk of CHD.

METHODS

Cross-sectional population-based study of 5029 men and women aged 59-80 years from primary care practices in Great Britain. Smoking, behavioural and demographic information was reported in questionnaires; nurses made physical measurements and took blood samples for analysis of serum cotinine and markers of inflammation, hemostasis and endothelial dysfunction.

RESULTS

Active cigarette smokers had lower albumin and higher triglycerides, CRP, IL-6, white cell count, fibrinogen, blood viscosity, factor VIII, VWF and t-PA than non-smokers. Among non-smokers, serum cotinine levels were independently positively associated with CRP, fibrinogen, factor VIII, VWF and t-PA and inversely associated with albumin, after adjustment for age, gender, social and behavioural factors. The differences in CRP, fibrinogen and albumin between cotinine < or =0.05 and >0.7 ng/ml were one-third to one half the size of differences between cotinine < or =0.05 ng/ml and current smokers, but were of similar magnitude for VWF and t-PA.

CONCLUSIONS

Endothelial, inflammatory and haemostatic markers related to CHD risk showed independent associations with SHS exposure in the same direction as those for active smoking. Results aid understanding of the associations between SHS exposure and elevated CHD risks.