Japan-multimodal intervention trial for the prevention of dementia in older people with lifestyle-related diseases: A community-based, 18-month, randomized controlled trial

Background The prevalence of Alzheimer's disease is increasing in Japan, highlighting the need to establish evidence-based strategies for its prevention. Objective We aimed to evaluate the effectiveness of a multimodal community-based intervention for Japanese older people with lifestyle-related diseases and to identify challenges in implementing such interventions to prevent dementia in local communities. Methods An 18-month randomized controlled trial was conducted among individuals aged 65–85 years with lifestyle-related diseases (hypertension, hyperlipidemia, diabetes, overweight/underweight, smoking), residing in a single apartment complex. Participants were randomly assigned to a multimodal intervention group (group-based physical exercise, nutritional guidance, management of lifestyle-related diseases, and cognitive training) or a control group. The primary outcome was the change in the composite score derived from seven neuropsychological tests. The trial was registered (UMIN000041887: September 24, 2020). Results Of 224 screened individuals, 198 were randomized (99 in each group), and 175 (88.4%) completed the 18-month assessment. There was no significant difference between the intervention and control groups in the primary outcome (change in composite test score: 0.25; 95% confidence interval 0.16 to 0.33 versus 0.29; 95% confidence interval 0.20 to 0.38, respectively; p = 0.463). However, a subgroup analysis of participants with mild cognitive impairment showed a significant intervention effect on changes in logical memory, for both immediate ( p = 0.041) and delayed recall tasks ( p = 0.043). Conclusions This multimodal intervention program demonstrated no effectiveness in mitigating cognitive decline. Further research is needed to develop more effective strategies and to better define target populations.