Although the correlation between cognition and physical function has been well studied in the general population, the genetic and environmental nature of the correlation has been rarely investigated. We conducted a classical twin analysis on cognitive and physical function, including forced expiratory volume in one second (FEV₁), forced vital capacity (FVC), handgrip strength, five-times-sit-to-stand test (FTSST), near visual acuity, and number of teeth lost in 379 complete twin pairs. Bivariate twin models were fitted to estimate the genetic and environmental correlation between physical and cognitive function. Bivariate analysis showed mildly positively genetic correlations between cognition and FEV₁, r_G = 0.23 [95% CI: 0.03, 0.62], as well as FVC, r_G = 0.35 [95% CI: 0.06, 1.00]. We found that FTSST and cognition presented very high common environmental correlation, r_C = -1.00 [95% CI: -1.00, -0.57], and low but significant unique environmental correlation, r_E = -0.11 [95% CI: -0.22, -0.01], all in the negative direction. Meanwhile, near visual acuity and cognition also showed unique environmental correlation, r_E = 0.16 [95% CI: 0.03, 0.27]. We found no significantly genetic correlation for cognition with handgrip strength, FTSST, near visual acuity, and number of teeth lost. Cognitive function was genetically related to pulmonary function. The FTSST and cognition shared almost the same common environmental factors but only part of the unique environmental factors, both with negative correlation. In contrast, near visual acuity and cognition may positively share part of the unique environmental factors.

Objectives: The heritability of age-related hearing loss has been studied mostly in developed countries. The authors aimed to estimate the heritability of better ear hearing level (BEHL), defined as hearing level of the better ear at a given frequency, and pure-tone averages at the middle (0.5, 1.0, and 2.0 kHz) and high (4.0, 8.0, and 12.5 kHz) frequencies among middle-aged and elderly Chinese twins, and to explore their genetic correlations. Design: This population-based twin study included 226 monozygotic and 132 dizygotic twin-pairs and 1 triplet (age range, 33 to 80 years; mean age, 51.55 years). Pure-tone air-conducted hearing thresholds in each ear were measured at the frequencies of 0.5, 1.0, 2.0, 4.0, 8.0, and 12.5 kHz with a diagnostic audiometer. Univariate and multivariate twin models were fitted to evaluate heritability and genetic correlations. Results: Our data showed a reverse J-shaped pattern of BEHLs at six frequencies by age and sex. Univariate analysis showed that the heritability of BEHLs at the frequencies between 2.0 and 12.5 kHz ranged from 47.08 to 54.20%, but the heritability at the frequencies of 0.5 and 1.0 kHz was 1.65% and 18.68%, respectively. The heritability of pure-tone average at the middle and high frequencies was 34.77% and 43.26%, respectively. Multivariate analysis showed significant genetic correlations among BEHLs at all six frequencies, with the correlation coefficients ranging from 0.48 to 0.83 at middle frequencies, and from 0.46 to 0.75 at high frequencies. Conclusions: This population-based twin study suggests that genetic factors are associated with age-related hearing loss at middle and high frequencies among middle-aged and elderly Chinese.

The associations between genetic factors and waist circumference (WC) with stroke risk have been evaluated in Western studies. However, evidence of this association has rarely been reported in the Chinese population. This study aimed to evaluate the association between WC and family history of stroke (FHS) with ischemic stroke (IS) risk among Chinese adults and to further explore the potential interaction of these associations. The China Kadoorie Biobank (CKB) study recruited 35,508 participants aged 30-79 years from the Qingdao urban area during 2004-2008. A total of 33,355 participants were included in study. Cox regression analysis was used to estimate the multivariable-adjusted hazard ratios (HR) and 95% confidence intervals (CI) for the independent and interactional associations between FHS and WC and IS risk. Participants with FHS had a 29% (HR = 1.29, 95% CI: 1.12-1.50) higher IS risk than those without FHS. Participants with excessive WC (85 cm for males and 80 cm for females) had a 78% (HR = 1.78, 95% CI: 1.51-2.10) higher IS risk than those with normal WC. The combined effect of FHS and excessive WC on IS was statistically significant (HR = 2.29, 95% CI: 1.84-2.86). The present study further found statistically significant multiplicative interactions of FHS and WC with IS risk (P_interaction < 0.001). The present study indicated that FHS and WC were significantly associated with an increased risk of IS. The association between FHS and IS was associated with excessive WC.

Background: Elevated fasting plasma glucose (FPG) levels can increase morbidity and mortality even when it is below the diagnostic threshold of type 2 diabetes mellitus (T2DM). We conducted a genome-wide DNA methylation analysis to detect DNA methylation (DNAm) variants potentially related to FPG in Chinese monozygotic twins.Methods: Genome-wide DNA methylation profiling in whole blood of twins was performed using Reduced Representation Bisulfite Sequencing (RRBS), yielding 551,447 raw CpGs. Association between DNAm of single CpG and FPG was tested using a generalized estimation equation. Differentially methylated regions (DMRs) were identified usingcomb-Papproach. ICE FALCON method was utilized to perform the causal inference. Candidate CpGs were quantified and validated using Sequenom MassARRAY platform in a community population. Weighted gene co-expression network analysis (WGCNA) was conducted using gene expression data from twins.Results: The mean age of 52 twin pairs was 52 years (SD: 7). The relationship between DNAm of 142 CpGs and FPG reached the genome-wide significance level. Thirty-two DMRs within 24 genes were identified, includingTLCD1,MRPS31P5,CASZ1, andCXADRP3. The causal relationship of top CpGs mapped toTLCD1,MZF1,PTPRN2,SLC6A18,ASTN2,IQCA1,GRIN1, andPDE2Agenes with FPG were further identified using ICE FALCON method.Pathways potentially related to FPG were also identified, such as phospholipid-hydroperoxide glutathione peroxidase activity and mitogen-activated protein kinase p38 binding. Three CpGs mapped toSLC6A18gene were validated in a community population, with a hypermethylated direction in diabetic patients. The expression levels of 18 genes (includingSLC6A18andTLCD1) were positively correlated with FPG levels.Conclusions: We detect many DNAm variants that may be associated with FPG in whole blood, particularly the loci withinSLC6A18gene. Our findings provide important reference for the epigenetic regulation of elevated FPG levels and diabetes.

Background: Previous studies linking dairy consumption with ischemic heart disease (IHD) are almost from western countries, with little from China. The present study was to explore the relationship between dairy consumption and IHD among Chinese adults. Methods: The data for the present study was from the prospective cohort study of China Kadoorie Biobank in Qingdao, a total of 33,355 participants in the present study. An interviewer-administered laptop-based questionnaire was used to collect information on the consumption frequency of dairy, incident IHD cases were identified through Disease Surveillance Point System and the new national health insurance databases. Cox regression analyses were performed to estimate adjusted hazard ratios (HRs) and confidence interval for the relationship between the incidence of IHD and dairy consumption. Results: The baseline survey reported that 32.4% of males and 34.6% of females consumed dairy regularly (i.e. ≥ 4 days/week). Over an average of 9.2 years follow-up, 2712 new-onset IHD were documented. Compared with participants who never or rarely consume dairy, the HR of consumed dairy regularly was 0.85(0.73–0.98) for males (P < 0.05), while no significant benefits were identified for females. Conclusions: Regular dairy consumption had an inverse association to the onset of IHD among males, with no similar findings for females.