Air quality improvement and cognitive decline in community-dwelling older women in the United States: A longitudinal cohort study.

BACKGROUND: Late-life exposure to ambient air pollution is a modifiable risk factor for dementia, but epidemiological studies have shown inconsistent evidence for cognitive decline. Air quality (AQ) improvement has been associated with improved cardiopulmonary health and decreased mortality, but to the best of our knowledge, no studies have examined the association with cognitive function. We examined whether AQ improvement was associated with slower rate of cognitive decline in older women aged 74 to 92 years. METHODS AND FINDINGS: We studied a cohort of 2,232 women residing in the 48 contiguous US states that were recruited from more than 40 study sites located in 24 states and Washington, DC from the Women's Health Initiative (WHI) Memory Study (WHIMS)-Epidemiology of Cognitive Health Outcomes (WHIMS-ECHO) study. They were predominantly non-Hispanic White women and were dementia free at baseline in 2008 to 2012. Measures of annual (2008 to 2018) cognitive function included the modified Telephone Interview for Cognitive Status (TICSm) and the telephone-based California Verbal Learning Test (CVLT). We used regionalized universal kriging models to estimate annual concentrations (1996 to 2012) of fine particulate matter (PM2.5) and nitrogen dioxide (NO2) at residential locations. Estimates were aggregated to the 3-year average immediately preceding (recent exposure) and 10 years prior to (remote exposure) WHIMS-ECHO enrollment. Individual-level improved AQ was calculated as the reduction from remote to recent exposures. Linear mixed effect models were used to examine the associations between improved AQ and the rates of cognitive declines in TICSm and CVLT trajectories, adjusting for sociodemographic (age; geographic region; race/ethnicity; education; income; and employment), lifestyle (physical activity; smoking; and alcohol), and clinical characteristics (prior hormone use; hormone therapy assignment; depression; cardiovascular disease (CVD); hypercholesterolemia; hypertension; diabetes; and body mass index [BMI]). For both PM2.5 and NO2, AQ improved significantly over the 10 years before WHIMS-ECHO enrollment. During a median of 6.2 (interquartile range [IQR] = 5.0) years of follow-up, declines in both general cognitive status (ß = -0.42/year, 95% CI: -0.44, -0.40) and episodic memory (ß = -0.59/year, 95% CI: -0.64, -0.54) were observed. Greater AQ improvement was associated with slower decline in TICSm (ßPM2.5improvement = 0.026 per year for improved PM2.5 by each IQR = 1.79 µg/m3 reduction, 95% CI: 0.001, 0.05; ßNO2improvement = 0.034 per year for improved NO2 by each IQR = 3.92 parts per billion [ppb] reduction, 95% CI: 0.01, 0.06) and CVLT (ßPM2.5 improvement = 0.070 per year for improved PM2.5 by each IQR = 1.79 µg/m3 reduction, 95% CI: 0.02, 0.12; ßNO2improvement = 0.060 per year for improved NO2 by each IQR = 3.97 ppb reduction, 95% CI: 0.005, 0.12) after adjusting for covariates. The respective associations with TICSm and CVLT were equivalent to the slower decline rate found with 0.9 to 1.2 and1.4 to 1.6 years of younger age and did not significantly differ by age, region, education, Apolipoprotein E (ApoE) e4 genotypes, or cardiovascular risk factors. The main limitations of this study include measurement error in exposure estimates, potential unmeasured confounding, and limited generalizability. CONCLUSIONS: In this study, we found that greater improvement in long-term AQ in late life was associated with slower cognitive declines in older women. This novel observation strengthens the epidemiologic evidence of an association between air pollution and cognitive aging.

Evaluation of the factor structure and psychometric properties of the Brief Symptom Inventory-18 with homebound older adults.

OBJECTIVE: Homebound older adults are at high risk for depression and anxiety. Systematic screening may increase identification of these difficulties and facilitate service usage. The purpose of this study was to investigate the factor structure, internal consistency, and concurrent validity of the Brief Symptom Inventory-18 (BSI-18) for use as a screening instrument for depression and anxiety with homebound older adults and to examine if the BSI-18 could be shortened further and exhibit comparable psychometric properties. METHODS: A sample of 142 older adults receiving in-home aging services completed interviews that included the BSI-18 and the depression and anxiety modules of the structured clinical interview for DSM-IV. RESULTS: Confirmatory factor analysis showed that the theorized three-factor, second-order model of the BSI-18 fit the data well (S-B X(2) = 136.17; p = 0.36). The depression and anxiety subscales exhibited high internal consistency (alpha > 0.81), whereas the somatic subscale exhibited lower internal consistency (alpha = 0.69). Receiver operator curve (ROC) analyses suggest that the BSI-18 depression and anxiety subscales were able to predict those with DSM-IV diagnoses (Depression AUC = 0.89 p < 0.001; Anxiety AUC = 0.80, p < 0.001). The ROC results suggested adapting a cut score of T = 50 to achieve optimal sensitivity and specificity. The short three-item depression scale exhibited comparable psychometric properties to the full scale, while the three-item somatic and anxiety scales exhibited lower internal consistency and sensitivity. CONCLUSIONS: These findings provide initial evidence that the BSI-18 is valid for use with homebound older adults.