Association of Cadmium and Lead Exposure With the Incidence of Contrast Sensitivity Impairment Among Middle-aged Adults

Abstract

Importance Contrast sensitivity (CS) is an important indicator of visual function that impacts daily life, including mobility, visually intensive tasks, safety, and autonomy. Understanding risk factors for CS impairment could lead to prevention of decreases in visual function. Objective Determine the incidence of CS impairment in a large cohort, and investigate factors potentially associated with incidence, including cadmium (Cd) and lead (Pb) levels. Design The Beaver Dam Offspring Study (BOSS, baseline 2005–2008) was conducted in the adult children of the participants of the population-based Epidemiology of Hearing Loss Study. Follow-up examinations occurred in 2010–2013 and 2015–2017. Setting Longitudinal cohort study Participants 1983 participants free of CS impairment at baseline. Particpants were primarily non-hispanic white, 51.8% women, mean age 48 years (standard deviation=9.3). Main Outcome CS was measured using Pelli-Robson Letter Sensitivity Charts, and incident impairment was defined as a log CS score less than 1.55 in either eye at any follow-up examination. Cd and Pb levels were measured in whole blood, using inductively coupled plasma mass spectrometry. Associations between baseline characteristics and CS impairment incidence were examined using Cox proportional hazard models and quantified as hazard ratios (HR) with 95% confidence intervals (CI). Results The 10-year cumulative incidence of CS impairment was 24.8%, was similar in women and men, and was highest in the oldest age group (64–84 years) at 66.3%. In multivariable models, a Cd level in the highest quintile (Q5 vs. Q1–4) (HR=1.35, CI=1.02, 1.78), age (per 5 years) (HR=1.34, CI=1.25,1.44), waist circumference (per 5 cm) (HR=1.06, CI=1.02,1.10), and number of plaque sites (1–3 vs. 0, HR=1.37, CI=1.03,1.81; 4–6 vs. 0, HR=2.63, CI=1.26,5.48) were associated with increased risk, while male sex (HR=0.77, CI=0.60,0.98) and any alcohol consumption (vs. none, HR=0.54, CI=0.39, 0.76) were associated with decreased risk. Results were similar when smoking status replaced Cd in the models. Lead level was not associated with increased risk. Conclusions and Relevance Incident CS impairment was common in the 10-year follow-up. Cd, but not Pb, was associated with increased risk. Other modifiable risk factors were associated with risk implying that changes in behavior could reduce future incident impairment.

Sensorineural Impairments, Cardiovascular Risk Factors, and 10-Year Incidence of Cognitive Impairment and Decline in Midlife: The Beaver Dam Offspring Study

“…As with CVRF/CVD, sensorineural impairments in midlife may be important predictors of concurrent and future cognitive health, but longitudinal studies that include multiple sensorineural measures in middle-aged adults are lacking. Because CVRF/CVD have been associated with the development of both sensorineural (20)(21)(22)(23)(24) and cognitive dysfunction (13)(14)(15)(16)(17)19), it is important to evaluate both sensorineural and CVRF/CVD in studies investigating predictors of cognitive decline or impairment. The purpose of the present study was to evaluate the longitudinal associations of sensorineural impairments and CVRF/CVD with impairment and declines in cognitive function over 10 years in a primarily middle-aged cohort.…”

Brain Aging in Midlife: The Beaver Dam Offspring Study

“…The Beaver Dam Offspring Study (BOSS) is a longitudinal study of the adult children of participants in the Epidemiology of Hearing Loss Study, a population‐based study of aging (1993‐present) . The baseline BOSS examination (BOSS1) occurred in 2005‐2008, and follow‐up examinations were conducted 5 years (BOSS2; 2010‐2013) and 10 years (BOSS3; 2015‐2017) later . Participants included in the analyses had to have BOSS1covariate data and complete sensory and cognitive data from BOSS2 (methods are detailed in the Supplementary Methods).…”

“…Pure‐tone air and bone conduction was used to measure hearing ability, and hearing function was defined as the pure‐tone average (PTA) of the thresholds at .5, 1, 2, and 4 kHz in the worse ear . Vision was measured by contrast sensitivity as log contrast sensitivity (CS) units based on triplet scores in the better eye . Olfactory function was measured using the San Diego Odor Identification Test (SDOIT), and the score was the number of correctly identified odors (Supplementary Methods).…”

“…23,24 The baseline BOSS examination (BOSS1) occurred in 2005-2008, and follow-up examinations were conducted 5 years (BOSS2; 2010-2013) and 10 years (BOSS3; 2015-2017) later. 23,[25][26][27][28] Participants included in the analyses had to have BOSS1covariate data and complete sensory and cognitive data from BOSS2 (methods are detailed in the Supplementary Methods). For the 5-year incidence analyses, participants also had to have complete sensory and cognitive data from BOSS3.…”

“…23 Vision was measured by contrast sensitivity as log contrast sensitivity (CS) units based on triplet scores in the better eye. 28 Olfactory function was measured using the San Diego Odor Identification Test (SDOIT), and the score was the number of correctly identified odors 25…”