This is the first study to test the effect of Tai Chi on pain from knee osteoarthritis in community-dwelling elders with mild cognitive impairment. If Tai Chi is effective in reducing pain, clinicians can use it routinely with this population; then elders can maintain their functional ability longer, and perhaps delay or prevent long-term care admission, and the investigators can save health care dollars.

Up to 33% of all elders and 40% of elders over age 70 experience knee osteoarthritis (OA), a leading cause of pain and disability. Further, up to 15.3% of elders age 65 have CI, and the prevalence of cognitive impairment (CI) doubles every 5 years after age 65. The prevalence of OA in elders with CI is comparable to that in elders without CI. Cognitive impairment limits elders' ability to perform daily activities, and their functional capacity declines more rapidly than in elders without CI. Having knee OA pain in addition to CI further limits elders' activities. Without proper treatment of knee OA pain, elders with CI may avoid basic daily activities, such as rising, walking, standing, and climbing stairs because these aggravate pain. By avoiding these basic activities, they gradually lose muscle strength, range of motion, and mobility, which leads to further physical deconditioning and social isolation. With aging of the baby boomers and advances in health care, the number of elders with both CI and OA will increase fourfold by 2050. Alleviating knee pain in elders with CI and knee OA could preserve their functioning, perhaps delay institutionalization, and save healthcare dollars. Since pharmacological interventions produce serious side effects and inadequately reduce pain, especially in elders with CI, adjuncts such as Tai Chi (TC) are needed. A low-impact aerobic exercise, TC involves slowly stretching the limbs and trunk and ultimately re-establishes normal mechanics of the knee joints, which reduces knee OA pain. The United States Arthritis Foundation and the American Geriatrics Society have endorsed TC to reduce knee OA pain; but no study has investigated the effect of TC on knee OA pain in elders with CI. The primary aims of this study are:

1. To test the efficacy of a modified TC program in reducing knee OA pain in community-dwelling elders with mild CI.
2. To test the efficacy of a modified TC program in improving physical function and quadriceps strength.
3. To investigate feasibility and compliance issues in conducting TC.
4. To estimate the clinical significance of TC for pain reduction in community dwelling elders with mild CI.

The results of this study will help us design a full-scale RCT with a precise estimate of the sample size and dosage of TC needed for reducing knee OA pain in community-dwelling elders with mild CI.

Inclusion Criteria:

1. Age 60 years or order;
2. A MMSE score of 18-28;
3. Diagnosis of knee OA based on medical history reviewed with elders or family members/staff and confirmation from the physician/APN;
4. Self-report of knee OA pain ≥ 2 on the VDS, or pain score ≥ 3 on the WOMAC pain subscale;
5. Ability to speak English;
6. Physician's/APN's permission to participate;
7. No regular exercise program in the past month;
8. Ambulation without assistance from staff or a walking device for 50 meters; and
9. Ability to stand and maintain balance for 1 minute without a walking device

Exclusion Criteria:

1. Uncorrectable moderate or severe hearing or vision deficits;
2. Parkinson's disease;
3. Cancer pain;
4. Chronic pain conditions, such as rheumatoid arthritis, fibromyalgia, or severe low back pain;
5. Diabetic neuropathy;
6. Arthroscopic surgery or total knee- or hip-replacement surgery in the past 6 months;
7. Fractures in the past 6 months;
8. Major psychiatric disorder or positive screen for depressive symptoms (GDS-15 score ≥ 5) without taking medication;
9. History of falls in the past 3 months; or
10. Vertigo in the past month