Mild cognitive impairment (MCI) is a transitional state between normal cognitive decline and dementia. Individuals with MCI are having an impairment in cognitive function compared with normal age-matched counterparts, while their cognitive function is still sufficient for their daily function. The prevalent rate of MCI is ranging from 10% to 20%. Patients with MCI are more susceptible to dementia with annual conversion rate between 5% and 20%. It is well-known that dementia not only lead to devastating consequences to the patients and their care-givers, but also immense healthcare and socioeconomic burdens. The growing prevalence of MCI in our rapidly aging population warrants immediate action to identify effective interventions to prevent progression of the cognitive impairment and its conversion to dementia. Currently, there is no pharmaceutical treatment proven to be effective in alleviating the cognitive decline in MCI patients. Nonetheless, previous researches have demonstrated that mind activity, physical exercise and social engagement are all have positive effects in alleviating the cognitive decline in MCI patients. Tai Chi is a traditional form of Chinese mind-body exercise that consists of both physical exercise and meditation component. Practicing Tai Chi can also facilitate social engagement as people usually practice in group. Tai Chi is expected to be more acceptable to the older adults for incorporating it with their daily life to preserve cognitive function, compared with conventional physical activity modalities (e.g., running/jogging and gym-based resistance training). Preliminary evidences suggest the potential of Tai Chi for alleviating cognitive decline in older adults.

A randomized controlled trial is needed to conclude on the therapeutic use of Tai Chi before it can be large-scale implemented at community level. This study seeks to extend previous findings of the beneficial effects of Tai Chi on cognitive function in older adults with MCI and examine the impact of Tai Chi training in protecting older adults with MCI from developing dementia. This study also attempt to delineate the behind mechanism of Tai Chi on alleviating cognitive decline by including measurements in neuroimaging and blood markers.

Inclusion Criteria:

• Older adults aged equal or larger than 50 years

• Ethnic Chinese

• MCI under criteria of Mayo Clinic, including the following:

  i. Participants have noticed a decline in their cognitive function ii. The total score of participants in age and education corrected Hong Kong version Montreal Cognitive assessment is below the 7th percentile of the normative data from Hong Kong iii. The decline of cognitive function does not affect the daily function of the participants revealed by getting ≥2 marks in every item of Chinese Lawton Instrumental Activities of Daily Living Scale (4-point Scale)

Exclusion Criteria:

• History of major diseases such as cancer, stroke, cardio-/cerebrovascular, neurodegenerative and renal diseases,
• Diagnosis of dementia or using anti-dementia medication,
• Diagnosis of psychiatric disease or using psychiatric medication,
• Inability to perform exercise,
• Regular mind-body exercise habit (>3 times 60-minute Tai Chi, yoga or Qigong weekly),
• Physically active (>150 minutes of moderate-intensity physical activity or >75 minutes of vigorous-intensity physical activity weekly)