Reaction Time as a Marker of Neurocognitive Decline. Measurement of Simple, Choice and Discrimination Reaction Time in Geriatric Subjects

Background: Reaction time (RT) is a critical indicator of cognitive-motor function and represents the time interval between stimulus presentation and voluntary response initiation. While RT decline with aging is well-documented, most assessments focus solely on simple reaction time (SRT), neglecting the more complex cognitive processes required in daily life. This study addresses the need for comprehensive, accessible RT assessment tools in geriatric populations. Objective: To measure and compare simple reaction time (SRT), choice reaction time (CRT), and discrimination reaction time (DRT) across different age groups in healthy geriatric subjects, and to validate the clinical utility of a low-cost, field-appropriate assessment method. Methods: A cross-sectional study was conducted with 80 community-dwelling adults aged 55–75 years, stratified into four age groups (55–60, 61–65, 66–70, and 71–75 years) with equal gender distribution. Three variations of the Ruler Drop Test were employed and reaction time was measured. Statistical analysis included one-way ANOVA with Tukey's post hoc comparisons. Results: All three RT measures demonstrated significant age-related increases (p < 0.001). SRT increased from 30.4 ± 3.82 cm in the youngest group to 46.6 ± 2.76 cm in the oldest group. CRT showed a similar pattern, rising from 34.8 ± 3.58 cm to 50.2 ± 3.24 cm. DRT increased from 33.4 ± 3.32 cm to 48.1 ± 4.18 cm. The most pronounced deterioration occurred in the 71–75 age group. Complex RT tasks (CRT and DRT) showed greater age-related decline than SRT, suggesting preferential impairment of higher-order cognitive processes. Conclusion: Reaction time increases significantly with advancing age, particularly after 70 years. The Ruler Drop Test offers a valid, reliable, and economically feasible tool for assessing cognitive-motor function in older adults. Also enables early detection of functional decline and fall risk assessment in both clinical and community settings, making it particularly valuable for resource-limited environments. The findings support the incorporation of comprehensive RT assessment into routine geriatric screening protocols to facilitate timely intervention and preserve functional independence.