Tai Chi Versus Conventional Exercise to Improve Cognitive Performance in Older Adults With Mild Cognitive Impairment

Inclusion Criteria: * Chinese older adults aged equal or larger than 50 years * Ethnic Chinese * MCI under criteria of Mayo Clinic, including the following i. people with subjective complaint about a decline in cognitive function. ii. total score in the Montreal Cognitive Assessment is equal or below the 7th percentile of the age- and education- corrected normative data of Hong Kong. iii. the decline in cognitive function does not impair daily functioning, as revealed by getting ≥2 marks in every item on the Chinese Lawton Instrumental Activities of Daily Living 4-point Scale). Exclusion Criteria: * medical history of major chronic diseases such as cancer, stroke, cerebro- and cardio-vascular diseases, and renal disease * uncontrolled diabetes * diagnosed with dementia or using anti-dementia medication * diagnosed with psychiatric diseases or using psychiatric medication * with diseases or on medications known to severely affect cognitive performance * somatic condition (e.g., limb lost) that prevent participation in exercise * impaired mobility by chronic diseases (e.g., neurological, musculoskeletal and autoimmune diseases) * incapable to perform physical exercise * regular exercise habit (\>3 times 60-min Tai Chi or moderate-intensity conventional exercise weekly) in the past 3 months