Effects of Internet-Based Dementia Risk Reduction Education on Risk and Protective Factor Knowledge, Intentions, and Health Behaviors: Randomized Controlled Trial

Background: Dementia prevention through the reduction of modifiable risk factors is gaining attention as a public health strategy. However, public knowledge of dementia risk and protective factors remains low. Web-based education offers a potential solution to raise awareness and promote risk-reduction behaviors. Objective: This randomized controlled trial evaluated the effectiveness of DementiaRisk.ca, an internet-based multimedia educational intervention, in increasing knowledge of dementia risk factors, intentions to engage in risk reduction behaviors, and changes in health behaviors. Methods: A 2-arm randomized controlled trial was conducted with 510 participants (265 in the intervention group and 245 in the control group). Participants were randomized to receive either the e-learning about dementia risk and promoting brain health, which included a multimedia lesson and microlearning emails, or a control intervention focused on mild cognitive impairment. Outcomes included knowledge of dementia risk factors, intentions to engage in risk reduction, and health behaviors, measured at baseline (T1), 4 weeks (T2), and 2 months postintervention (T3). Outcomes were analyzed using linear mixed effects models with fixed effects for group, time, and their interaction, and a random intercept for participants. Results: Of the 510 randomized participants, 405 (79.4%) completed all intervention components. Participants were predominantly female (n=309, 60.6%) and aged 55 years or older (n=284, 55.7%). Baseline mean dementia knowledge scores were 17.0 (SD 5.5) in the intervention group and 17.4 (SD 6.0) in the control group. At T2, scores increased to 25.8 (SD 4.5) and 23.6 (SD 5.1), respectively, yielding a between-group difference of 2.2 points (95% CI 1.2‐3.2; <.001), which was sustained at T3. Both groups showed significant improvements in knowledge, intentions, and health behaviors over time, with larger knowledge gains in the intervention group and particularly among participants with lower educational attainment. Intentions to engage in dementia risk reduction improved in both groups at T2 (intervention: +1.0, 95% CI 0.2‐1.8; control: +1.4, 95% CI 0.5‐2.3), with no significant between-group difference. Self-reported physical activity increased from 31.7 (SD 25.0) to 38.6 (SD 27.5) in the intervention group and from 29.9 (SD 23.5) to 32.5 (SD 26.6) in the control group, with a between-group difference of 5.4 points at T2 (95% CI 0.3‐10.5; =.04). No significant between-group differences were observed for diet, alcohol use, or other health behaviors. Qualitative findings indicated that participants valued the intervention for improving awareness of dementia risk factors, motivating proactive lifestyle changes, and enhancing confidence in applying prevention information. Conclusions: This internet-based dementia risk reduction e-learning program improved dementia-related knowledge and increased self-reported physical activity, particularly among participants with lower educational attainment. Effects on other health behaviors were limited. These findings support the use of well-designed e-learning as a scalable public health strategy to strengthen dementia risk reduction literacy and encourage selected healthy behaviors. Trial Registration: ClinicalTrials.gov NCT05383118; https://clinicaltrials.gov/study/NCT05383118 International Registered Report Identifier (IRRID): RR2-10.2196/64718