Fermented Papaya and Driving Simulator Older Adult Study

Background: Driving is a critical determinant of independence, social participation, and access to healthcare among older adults. Age-related declines in attention, executive function, working memory, and processing speed can adversely affect driving performance and increase the risk of crashes and driving cessation. Fermented papaya preparation (FPP®), a nutraceutical with antioxidant and anti-inflammatory properties, has shown promise for supporting cognitive function in older adults. However, its effects on driving performance have not been previously investigated. Objective: To examine the short- and long-term effects of FPP® supplementation on driving performance and associated cognitive functions in community-dwelling older adults aged 70–80 years using a high-fidelity driving simulator. Methods: An experimental repeated-measures design was employed in which participants served as their own controls. Fifty-nine older adults were enrolled, with 34 completing all three study visits. Participants completed a baseline assessment (Visit 1), a short-term assessment within approximately 24 h after receiving three 3 g doses of FPP® (Visit 2), and a long-term assessment following eight weeks of daily FPP® intake (Visit 3). Assessments included visual and cognitive testing, the Useful Field of View (UFOV), quality-of-life measures, and a standardized simulator-based driving evaluation that quantified total driving errors and errors related to attention, working memory, reaction time, and executive function. Non-parametric analyses, Bayesian testing, and generalized estimating equations (GEEs) were used to evaluate efficacy and safety outcomes. Results: Unadjusted analyses demonstrated no statistically significant reductions in total driving errors by comparing baseline testing to eight weeks after the use of FPP®; however, executive function errors exhibited a favorable trend (p = 0.065; r = 0.307). Across all driving measures, short-term exposure to three doses of FPP® produced no evidence of impaired driving performance, with Bayesian analyses providing moderate support for the absence of detrimental effects. Significant improvements were observed in UFOV Divided Attention (p = 0.008) and overall crash-risk categorization (p = 0.046), indicating enhanced cognitive processing speed and attentional performance. After adjusting for baseline cognition, visual acuity, and compliance, GEE modeling demonstrated a trend toward reduced total driving errors after eight weeks of FPP® supplementation (incidence rate ratio (IRR) = 0.79, p = 0.065), corresponding to approximately 21% fewer driving errors. Sensitivity analyses excluding participants with severe lower-extremity musculoskeletal impairments (n = 2) strengthened the intervention effect, revealing a statistically significant 25% reduction in total driving errors (IRR = 0.75, p = 0.031). Conclusions: FPP® supplementation did not produce evidence of detrimental effects on driving performance under the tested conditions and may confer meaningful cognitive and functional benefits relevant to driving performance. Improvements in divided attention and reductions in driving errors suggest that FPP® may represent a promising, non-invasive intervention to support driving safety and prolong mobility and independence among older adults. Larger controlled trials are warranted to confirm these findings and establish clinical recommendations for FPP® use in aging populations.