Associations between air pollution and biomarkers of Alzheimer's disease in cognitively unimpaired individuals

Phthalates exposure and pubertal development in a 15-year follow-up birth cohort study in Taiwan

Purpose

Phthalates are ubiquitous endocrine disruptors that can affect pubertal development in children. The association of fetal and childhood levels of phthalates with pubertal development were explored.

Methods

We conduct a population-based birth cohort study to investigate the association between prenatal and childhood exposure to phthalates and pubertal development. Initially, a total of 445 children were recruited from 2000 to 2001, of which 90 children were followed for 15 years which measurements of urine and development assessed at 2, 5, 8, 11, and 14 years. We defined higher Tanner stage as the 14-year-old Tanner stage ≥ 4 and 5 for boys and girls, respectively. A logistic regression analysis was conducted to estimate the crude and adjusted odds ratio of a higher Tanner stage at 14 years old. The Pearson correlation coefficient and multiple linear regression were used to estimate the association of testicular volume, uterine volume, ovarian volume, and blood hormones at 14 years of age with the log-transformed concentration of phthalates at 2, 5, 8, 11, and 14 years.

Results

In boys, a significantly different geometric mean of mono-benzyl phthalate (MBzP) was observed in 11-year-olds; 6.82 and 2.96 in the lower Tanner stage group and higher Tanner stage group. In girls, a significant difference in the geometric mean of mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) in 11-year-olds and mono-ethyl phthalate (MEP) in 2-year-olds was observed; MEHHP was 32.97 and 18.13 in the lower Tanner stage group and higher Tanner stage group, and MEP was 26.54 and 65.74 in the lower Tanner stage group and higher Tanner stage group, respectively. Uterine volume at 14 years old was negatively associated with several phthalate metabolites (MEHP at 8 years old, MnBP at 8 years old, MBzP at 14 years old, MMP prenatally, MMP at 8 years old, and MEP at 8 years old) after adjusting for covariates. However, no significant correlations were found between phthalate metabolites and ovarian or testicular volume.

Conclusion

Phthalate exposure at certain time points may influence the reproductive development of children during puberty; however, further studies should be conducted to determine the causal nature of this association.

Exposure to air pollution and risk of incident dementia in the UK Biobank

BACKGROUND

Air pollution may cause inflammatory and oxidative stress damage to the brain, leading to neurodegenerative disease. The association between air pollution and dementia, and modification by apolipoprotein E genotype 4 (APOE-ε4) has yet to be fully investigated.

OBJECTIVES

To examine associations of air pollution with three types of incident dementias (Alzheimer's disease (AD), frontotemporal dementia (FTD), and vascular dementia (VAD)), and their potential modification by APOE-ε4 genotype.

METHODS

The UK Biobank enrolled >500,000 participants (2006-2010) with ongoing follow-up. We used annual averages of air pollution (PM_2.5, PM₁₀, PM_2.5-10, PM_{2.5absorbance}, NO₂, NO_X) for 2010 scaled to interquartile ranges (IQR). We included individuals aged ≥60 years, with no dementia diagnosis prior to January 1, 2010. Time to incident dementia and follow-up time were reported from baseline (January 01, 2010) to last censor event (death, last hospitalization, or loss to follow-up). Cox proportional hazard ratios (HR) and 95% confidence intervals (95% CI) were calculated to estimate the association of air pollutants and incident dementia, and modification of these associations by APOE-ε4.

RESULTS

Our sample included 187,194 individuals (including N = 680 AD, N = 377 VAD, N = 63 FTD) with a mean follow-up of 7.04 years. We observed consistent associations of PM_2.5 with greater risk of all-cause dementia (HR = 1.17, 95% CI: 1.10, 1.24) and AD (HR = 1.17, 95% CI: 1.06, 1.29). NO₂ was also associated with greater risk of any incident dementia (HR = 1.18, 95% CI: 1.10, 1.25), AD (HR = 1.15, 95% CI: 1.04, 1.28) and VAD (HR = 1.18, 95% CI: 1.03, 1.35). APOE-ε4 did not modify the association between any air pollutants and dementia.

DISCUSSION

PM_2.5 and NO₂ levels were associated with several types of dementia, and these associations were not modified by APOE-ε4. Findings from the UK Biobank support and extend to other epidemiological evidence for the potential association of air pollutants with detrimental brain health during aging.