Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 51 1 2022 01 03 1 11 Sunweon Yun Department of Nursing, Mokpo National University, Jeollanamdo, Republic of Korea Seang Ryu Department of Nursing, Mokpo National University, Jeollanamdo, Republic of Korea 2021 03 29 2021 04 14 Background: Cognitive-based intervention is divided into three types: Cognitive Stimulation (CS), Cognitive Training (CT), and Cognitive Rehabilitation (CR). This study was conducted to identify systematically the effects of cognitive-based interventions in randomized controlled trials (RCTs) applied to older adults in the following three groups: cognitively healthy, mild cognitive impairment (MCI), and dementia. Methods: This search was carried out using the Ovid-MEDLINE, EMBASE, Cochrane library, CINAHL, ProQuest, and Korea databases. The effectiveness of the intervention was verified using the CMA 2.0 program. Results: A total of 54 RCTs were included in systematic reviews and 38 studies were analyzed by meta-analysis. Meta-analysis showed that cognitive-based interventions were effective in improving the cognitive function (SMD=0.39, 95% CI=0.32-0.44) of older adults. The subgroup analysis of cognitive function revealed that CT was the most effective in the cognitively healthy (SMD=0.40, 95% CI=0.33-0.46) and the MCI (SMD=0.45, 95% CI=0.27-0.63) groups, and CS was the most effective in the dementia group (SMD=0.57, 95% CI=0.43-0.70). Conclusion: In order to improve the cognitive function of older adults in each group, the most effective intervention type needs to be considered first. Evidence on the appropriate type of Cognitive-based intervention will be helpful in nursing practice. https://ijph.tums.ac.ir/index.php/ijph/article/view/24350 https://ijph.tums.ac.ir/index.php/ijph/article/download/24350/7460