Introduction and purpose: Physical inactivity in the elderly is an important risk factor for the development of cognitive impairment and Alzheimer’s disease. This study aimed to investigate the effect of Aerobics, ware aerobic exercise, and water-based exercise training on working memory of elderly women diagnosed with Alzheimer's disease.
Materials and Methods: This was a quasi-experimental study with three groups' pre-test post-test design. The participants, 30 elderly women diagnosed with Alzheimer's disease, with the mean age of 64 years were randomly assigned into three groups (aerobic, water aerobic exercise, and water-based exercise training). The training protocol consisted of 18 sessions, and each session lasted 45 minutes. The Wechsler Memory Scale (WMS) was used to measure the memory and the N-Back software was used to assess the working memory of the study participants. Data were analyzed using the SPSS software version22. Two-way repeated measurement ANOVA (3 group × 2 times) and paired sample t-test were used to analyze the data.
Findings: After the training, participants in all groups had better working memory status. However, the participants in the water aerobic exercise group showed greater improvement in working memory compares to other groups. There were significant differences between the three groups in the three subscales of visual memory, associated learning, and memory span. 
Conclusion: The result of this study indicated that water aerobic exercise can effectively improve the cognitive function of elderly women diagnosed with Alzheimer’s disease. The study findings could be useful guidelines for enhancing the cognitive function of elderly patients.