Two separate, large cohorts reveal potential modifiers of age-associated variation in visual reaction time...

To identify potential factors influencing age-related cognitive decline and disease, we created MindCrowd. MindCrowd is a cross-sectional web-based assessment of simple visual (sv) reaction time (RT) and paired-associate learning (PAL). svRT and PAL results were combined with 22 survey questions. Analysis of svRT revealed education and stroke as potential modifiers of changes in processing speed and memory from younger to older ages (n_total = 75,666, n_women = 47,700, n_men = 27,966; ages 18-85 years old, mean (M)_Age = 46.54, standard deviation (SD)_Age = 18.40). To complement this work, we evaluated complex visual recognition reaction time (cvrRT) in the UK Biobank (n_total = 158,249 n_women = 89,333 n_men = 68,916; ages 40-70 years old, M_Age = 55.81, SD_Age = 7.72). Similarities between the UK Biobank and MindCrowd were assessed using a subset of MindCrowd (UKBb MindCrowd) selected to mirror the UK Biobank demographics (n_total = 39,795, n_women = 29,640, n_men = 10,155; ages 40-70 years old, M_Age = 56.59, SD_Age = 8.16). An identical linear model (LM) was used to assess both cohorts. Analyses revealed similarities between MindCrowd and the UK Biobank across most results. Divergent findings from the UK Biobank included (1) a first-degree family history of Alzheimer's disease (FHAD) was associated with longer cvrRT. (2) Men with the least education were associated with longer cvrRTs comparable to women across all educational attainment levels. Divergent findings from UKBb MindCrowd included more education being associated with shorter svRTs and a history of smoking with longer svRTs from younger to older ages.