Clock Drawing Performance Differences in World Trade Center Responders at Midlife

Abstract Objective World Trade Center (WTC) responders demonstrate elevated risk for cognitive impairment (CI) consistent with Alzheimer’s Disease and Related Dementias (ADRD). Neuropsychological test performance is valuable in early detection efforts and non-invasive longitudinal tracking of populations at risk of ADRD. We hypothesized that WTC-CI would be associated with a greater number of errors on the clock drawing task (CDT). Method The CDT was administered to responders with/without CI who participated in a case/control study. WTC-CI was diagnosed following NIA-AA guidelines for diagnosing early-onset ADRD (ages <66 years). CDT performance was evaluated using subsets of clock errors derived from four existing variations in CDT evaluation measuring the number of errors. An ANOVA was conducted to compare mean differences in clock characteristics. Results From 99 participants, responders with CI (n = 50, Mage = 55.82) had more errors when compared to responders without CI (n = 49, Mage = 55.94) in the following CDT components: contour (p = 0.006), hands (p < 0.001), hands similarity (p = 0.005), moderate graphical errors (p = 0.042), left-side number crowding (p = 0.038), time incorrectness (p < 0.001), and extra marks on clock face (p = 0.006). Conclusion In this study, we demonstrated that CDT performance decline is associated with WTC-CI. CDT can be used as a non-invasive investigative tool that can track cognitive performance longitudinally, which can better aid in the early detection, monitoring, and intervention strategies when dealing with the emergence of encephalopathy in high-risk ADRD populations, such as the WTC cohort. Future research should evaluate additional measures that can address other comorbid issues that can arise in such populations, such as post-traumatic stress disorder (PTSD).