Ambient Air Pollution, Cognitive Impairment, and Dementia Among Older Patients Being Evaluated for Kidney Transplantation.

BACKGROUND

Older patients who are evaluated for kidney transplantation (KT) experience an earlier onset of cognitive impairment due to dialysis, comorbidities, and inactivity. Ambient fine particulate matter (PM2.5) is a modifiable risk factor for dementia among community-dwelling older adults. Inflammatory responses and oxidative stress caused by inactivity in older patients evaluated for KT may heighten vulnerability to PM2.5. Thus, the impact of PM2.5 on dementia may be more severe in this population.

METHODS

We leveraged a prospective cohort (2009-2019) of older (age ≥ 50) patients evaluated for KT (n = 2073) with Modified Mini-Mental State Examination (3MS). We derived annual PM2.5 from residential ZIP codes (high: PM2.5 > 9 µg/m3), quantifying its association with global cognitive function (linear regression), impairment (logistic regression), and risk of dementia (Cox proportional hazards model). We tested the interaction between PM2.5 and dementia risk factors using a Wald test. Models were adjusted for confounders, including social determinants of health.

RESULTS

High PM2.5 was associated with worse global cognitive function (difference = -3.00 points [3MS score], 95% CI: -3.93 to -2.07), with a stronger association among patients with low physical activity (p [interaction] < 0.001). High PM2.5 was associated with 1.90-fold higher odds of global cognitive impairment (95% CI: 1.48-2.46), and 3.29-fold higher risk of dementia (95% CI: 1.14-9.55).

CONCLUSION

High PM2.5 was associated with worse cognitive function among older patients evaluated for KT, particularly those with low physical activity. The association was stronger than prior findings among community-dwelling older adults. Clinicians may counsel patients to monitor air quality. Patients in high PM2.5 neighborhoods should discuss cognitive assessments and ways to increase physical activity with providers.