Associations between air pollution and psychiatric symptoms in the normative aging study

Background: Environmental risk factors for psychiatric health are poorly identified. We examined the association between air pollution and psychiatric symptoms, which are often precursors to the development of psychiatric disorders. Methods: This study included 570 participants in the US Veterans Administration (VA) Normative Aging Study and 1,114 visits (defined as an onsite follow-up at the VA with physical examination and questionnaires) from 2000-2014 with information on the Brief Symptom Inventory (BSI) to assess their psychiatric symptom levels. Differences in the three BSI global measures (Global Severity Index – GSI, Positive Symptom Distress Index – PSDI and Positive Symptom Total - PST) were reported per interquartile (IQR) increase of residential address-specific air pollutants levels (fine particulate matter – PM2.5, ozone - O3, nitrogen dioxide – NO2) at averages of 1 week, 4 weeks, 8 weeks and 1 year prior to the visit using generalized additive mixed effects models. We also evaluated modification by neighborhood factors. Results: On average, among the NAS sample (average age, 72.4 yrs. (standard deviation: 6.7 yrs.)), an IQR increase in 1- and 4- week averages of NO2 before visit was associated with a PSDI T score (indicator for psychiatric symptom intensity) increase of 1.60 (95% Confidence Interval (CI): 0.31, 2.89), 1.71 (95% CI: 0.18, 3.23), respectively. Similarly, for each IQR increase in 1- and 4-week averages of ozone before visit, PSDI T-score increased by 1.66 (95% CI: 0.68, 2.65), and 1.36 (95% CI: 0.23, 2.49), respectively. Stronger associations were observed for ozone and PSDI in low house value and low household income areas. No associations were found for PM2.5. Conclusions: Exposure to gaseous air pollutants was associated with higher intensity of psychiatric symptoms among a cohort of older men, particularly in communities with lower socio-economic or housing conditions.

Does HbA1c Influence the Relationship between Stress and Cognition? Findings from the VA Normative Aging Study

Type 2 diabetes has increased in prevalence globally, with potential adverse effects on cognition. Both high levels of hemoglobin A1c (HbA1c) and stressful life events (SLEs) are associated with impaired cognitive performance, but few studies have examined their synergistic effects. The present study examined direct effects of stress and HbA1c on several cognitive outcomes, and whether HbA1c moderated the relationship between SLEs and cognition. Utilizing a sample of 527 older men from the VA Normative Aging Study (Mage = 74.3, SD = 6.5), stress was inversely related to MMSE, verbal fluency, and pattern recognition; HbA1c was only inversely associated with MMSE. The moderation model was supported only for pattern recognition (𝛽 = 1.64, p < .05), with stress having worse effects in those high in HbA1c. Stratifying analyses by age group (<75, 75+) showed that stress predicted cognition only in the young-old, while HbA1c was inversely related to cognition only in old-old participants. Further, these age-group analyses yielded different effects of demographics on cognition. In the young-old, age was consistently inversely related to all cognitive outcomes, but in the old-old only with MMSE and word list recall. Among the young-old, education was associated with only word list recall but improved performance for most scales among the old-old. Finally, HbA1c intensified the effect of stress moderation on verbal fluency only in old-old (𝛽 = 2.78, p < .05). In summary, stress was more important for cognition in the young-old, while education and health status were more important in the old-old.