BackgroundCognitive function, working memory, attention, and coordination are higher-level functions sharing a complex relationship. Limited evidence exists on the effectiveness of multi-domain cognitive function interventions to improve cognitive outcomes. We evaluated the effectiveness of such interventions on cognitive function, working memory, attention, and coordination in older adults with mild cognitive impairment and mild dementia.MethodsWe conducted a double-blind, two-arm, parallel-group randomised controlled trial in community care centres of Northern Taiwan. We recruited 72 participants aged≥65 years and randomly allocated them using 1:1 block randomization (block size = 4) into experimental (multi-domain cognitive function training) (MCFT) and control groups (passive information activities) (PIA) (n = 36/group). We administered the interventions in both groups for 30 minutes per session, three sessions per week for eight weeks, for a total of 24 sessions. The outcome indicators were cognitive function assessed (mini-mental status examination), working memory (digit span), selective attention (Stroop test), visual-spatial attention (trail making test-A (TMT-A)), divided attention (trail making test-B (TMT-B)), and coordination (Berry visual-motor integration (Berry-VMI)). We evaluated the study outcomes at baseline, immediate post-test, one-month follow-up, and one-year follow-up.ResultsWe found no significant differences between the groups at baseline except for education. The average age of participants was 82.3 years, and most (76.4%) were female. We analysed the results by generalised estimating equations (GEE) based on the intention-to-treat (ITT) principle. The multi-domain cognitive function training was effective in improving cognitive function (β = 1.7; 95% confidence interval (CI) = 0.63-2.31;P= 0.001), working memory (β = -1.45; 95% CI = -2.62, -0.27;P= 0.016), and selective attention (β = -23.3; 95% = CI -43.9, -2.76;P= 0.026) compared to passive information activities at 1-month follow-up. The effects of multi-domain cognitive function training on cognitive function (β = 1.51; 95% CI = 0.40-2.63;P= 0.008), working memory (β = -1.93; 95% CI -3.33, -0.54;P= 0.007), selective attention (β = -27.8; 95% CI = -47.1, -8.48;P= 0.005), and coordination (β = 1.61; 95% CI = 0.25, 2.96;P= 0.020) were maintained for one year. There were no significant improvements in attention outcomes (visual-spatial and divided attention) after training.ConclusionsMCFT intervention demonstrated favourable effects in improving global cognitive function, working memory, selective attention, and coordination among older adults with mild cognitive impairment and mild dementia. Thus, applying multi-domain cognitive training in older adults with mild cognitive impairment and mild dementia could help to delay the cognitive decline.RegistrationChinese Clinical Trial Registry (ChiCTR2000039306).