Association between proximity to a lead releasing facility and cognition in diverse cohorts

While lead exposure is associated with poorer cognitive performance in children, the association with late life cognition in diverse cohorts is unknown.

In two adult cohorts (Kaiser Health Aging and Diverse Life Experiences (KHANDLE, n=1,638), Study of Healthy Aging in African Americans (STAR, n=741)), we assessed residential proximity to lead releasing facilities, measured through the Toxics Release Inventory, for associations with domain-specific cognition, measured using the Spanish and English Neuropsychological Assessment Scales, two years later. Linear regression models were adjusted for age, sex, race/ethnicity (KHANDLE only), income, education, marital status, smoking status, and alcohol consumption. We meta-analyzed across cohorts.

The average age at cognitive test was 76.1 years (KHANDLE) and 68.8 years (STAR) and the average distance between residence and lead releasing facility was 8.2 km (KHANDLE) and 3.6 km (STAR). In meta-analysis, for every 5 km closer a residential address was located to a lead releasing facility we observed -0.05 standard deviation lower verbal episodic memory (95% CI: -0.08, -0.02). Living within a 3 km buffer of a lead releasing facility was associated with -0.10 lower semantic memory (95% CI: -0.18, -0.02) and -0.08 lower global cognition (95% CI: -0.14, -0.02).

Residential proximity to a lead releasing facility was associated with poorer cognition two years later among adults in two cohorts. Comprehensive understanding of environmental factors is critical for dementia prevention.