Tobacco exposure and sleep disturbance in 498 208 UK Biobank participants

Background

The prevalence of sleep disturbance is high and increasing. The study investigated whether active, former and passive smoking were associated with sleep disturbance.

Methods

This cross-sectional study used data from the UK Biobank: a cohort study of 502 655 participants, of whom 498 208 provided self-reported data on smoking and sleep characteristics. Multivariable multinomial and logistic regression models were used to examine the associations between smoking and sleep disturbance.

Results

Long-sleep duration (>9 h) was more common among current smokers [odds ratio (OR): 1.47; 95% confidence interval (CI): 1.17-1.85; probability value (P) = 0.001] than never smokers, especially heavy (>20/day) smokers (OR: 2.85; 95% CI: 1.66-4.89; P < 0.001). Former heavy (>20/day) smokers were also more likely to report short (<6 h) sleep duration (OR: 1.41; 95% CI: 1.25-1.60; P < 0.001), long-sleep duration (OR: 1.99; 95% CI: 1.47-2.71; P < 0.001) and sleeplessness (OR: 1.47; 95% CI: 1.38-1.57; P < 0.001) than never smokers. Among never smokers, those who lived with more than one smoker had higher odds of long-sleep duration than those not cohabitating with a smoker (OR: 2.71; 95% CI: 1.26-5.82; P = 0.011).

Conclusions

Active and passive exposure to high levels of tobacco smoke are associated with sleep disturbance. Existing global tobacco control interventions need to be enforced.

Dietary fat and total energy intake modifies the association of genetic profile risk score on obesity: evidence from 48 170 UK Biobank participants

BACKGROUND

Obesity is a multifactorial condition influenced by both genetics and lifestyle. The aim of this study was to investigate whether the association between a validated genetic profile risk score for obesity (GPRS-obesity) and body mass index (BMI) or waist circumference (WC) was modified by macronutrient intake in a large general population study.

METHODS

This study included cross-sectional data from 48 170 white European adults, aged 37-73 years, participating in the UK Biobank. Interactions between GPRS-obesity and macronutrient intake (including total energy, protein, fat, carbohydrate and dietary fibre intake) and its effects on BMI and WC were investigated.

RESULTS

The 93-single-nucleotide polymorphism (SNP) GPRS was associated with a higher BMI (β: 0.57 kg m^-2 per s.d. increase in GPRS (95% confidence interval: 0.53-0.60); P=1.9 × 10^-183) independent of major confounding factors. There was a significant interaction between GPRS and total fat intake (P_{(interaction)}=0.007). Among high-fat-intake individuals, BMI was higher by 0.60 (0.52, 0.67) kg m^-2 per s.d. increase in GPRS-obesity; the change in BMI with GPRS was lower among low-fat-intake individuals (β: 0.50 (0.44, 0.57) kg m^-2). Significant interactions with similar patterns were observed for saturated fat intake (high β: 0.66 (0.59, 0.73) versus low β: 0.49 (0.42, 0.55) kg m^-2, P_{(interaction)}=2 × 10^-4) and for total energy intake (high β: 0.58 (0.51, 0.64) versus low β: 0.49 (0.42, 0.56) kg m^-2, P_{(interaction)}=0.019), but not for protein intake, carbohydrate intake and fibre intake (P_{(interaction)} >0.05). The findings were broadly similar using WC as the outcome.

CONCLUSIONS

These data suggest that the benefits of reducing the intake of fats and total energy intake may be more important in individuals with high genetic risk for obesity.

DNA yield and quality of saliva samples and suitability for large-scale epidemiological studies in children

OBJECTIVE

To evaluate two saliva collection methods for DNA yield and quality as applied to a large, integrated, multicentre, European project involving the collection of biological material from children.

DESIGN

Cross-sectional multicentre comparative study in young children.

METHODS

Saliva samples were collected from 14,019 children aged 2-9 years from eight European countries participating in the IDEFICS (Identification and prevention of dietary- and lifestyle-induced health effects in children and infants) study. This involved either the collection of 2 ml of saliva from children who were able to spit, or using a sponge to collect whole saliva and buccal mucosal cells from the inside of the mouth of younger children unable to spit. Samples were assembled centrally in each participating centre and subsequently despatched for DNA extraction and biobanking to the University of Glasgow. A subgroup of 4678 samples (∼33% of sampled individuals) were chosen for DNA extraction before genotyping.

RESULTS

The whole-saliva collection method resulted in a higher DNA yield than the sponge collection method (mean±s.d.; saliva: 20.95±2.35 μg, sponge: 9.13±2.25 μg; P<0.001). DNA quality as measured by A (260)/A (280) was similar for the two collection methods. A minimum genotype calling success rate of 95% showed that both methods provide good-quality DNA for genotyping using TaqMan allelic discrimination assays.

CONCLUSIONS

Our results showed higher DNA yield from the whole-saliva collection method compared with the assisted sponge collection. However, both collection methods provided DNA of sufficient quantity and quality for large-scale genetic epidemiological studies.

Developmental changes in adiposity in toddlers and preschoolers in the GENESIS study and associations with the ACE I/D polymorphism

OBJECTIVES

To investigate the relationship between the angiotensin I-converting enzyme 1 (ACE) I/D polymorphism and adiposity-related phenotypes in a large cohort of toddlers and preschoolers.

METHODS

Body composition measurements and DNA samples were obtained from 2102 Greek children aged 1-6 years, as part of a large-scale epidemiological study (GENESIS). All children were genotyped for the ACE I/D polymorphism and gender- and age-stratified statistical analyses were performed.

RESULTS

In girls aged 4-6 years, the D-allele was associated with higher measurements of body mass index (BMI) (P=0.018), waist (P=0.001) and upper arm (P=0.013) circumferences, genotype accounting for 2.5, 4 and 3% of the phenotypic variance, respectively. In boys, the D-allele showed strong associations with lower BMI (P=0.001) at the age of 1-2 years that explained 17% of the phenotypic variance and with larger suprailiac skinfold (P=0.008) at 3-4 years old that explained 2% of the variance. No other significant associations between the ACE I/D polymorphism and adiposity-related phenotypes were found. In girls, the age at which significant associations were revealed coincided with the age at which BMI was observed to increase after its developmental nadir, but this feature of the association was not observed in boys.

CONCLUSIONS

The ACE I/D polymorphism is associated with developmental and physiological changes in adiposity-related traits during early childhood in a gender- and age-specific manner.