Evidence Supports the Validity and Reliability of Response Times from a Brief Survey as a Digital Biomarker for Processing Speed in a Large Panel Study.

Survey response times (RTs) have hitherto untapped potential to allow researchers to gain more detailed insights into the cognitive performance of participants in online panel studies. We examined if RTs recorded from a brief online survey could serve as a digital biomarker for processing speed. Data from 9,893 adults enrolled in the nationally representative Understanding America Study were used in the analyses. Hypotheses included that people's average survey RTs would have a large correlation with an established processing speed test, small to moderate correlations with other cognitive tests, and associations with functional impairment. We also hypothesized that survey RTs would have sensitivity to various participant characteristics comparable to the established processing speed test's sensitivity (e.g., similar standardized means by gender). Overall, results support the validity and reliability of people's average RTs to survey items as a digital biomarker for processing speed. The correlation between survey RTs (reverse scored) and the formal processing speed test was 0.61 (p<0.001), and small to moderate associations with most other cognitive and functional status measures were observed. Sensitivity of survey RTs to various participant characteristics was nearly identical to the formal processing speed test. Survey RTs may be useful as proxies for processing speed.