Most research on Tai Chi has been done in the area of balance and falls. Studies examining the effects of Tai Chi exercise on cognitive function are sparse especially in the population of MCI. Therefore, the aims of the present study are: 1) to examine the effects of Tai Chi exercise on cognitive function of elderly with MCI, and 2) to investigate the effects of 6-month Tai Chi exercise on serum biomarkers in individuals with MCI.

Mild Cognitive Impairment (MCI) is a transitional stage before converting from normal aging to dementia. Older adults with MCI are 10 times more likely to develop dementia than cognitively intact older adults. Thus, strategies that could deter the conversion from MCI to dementia will have significant impact on public health.

There is growing interest in non-pharmacological approaches that could potentially slow down cognitive decline in late life. One such approach is the use of exercise to improve cognitive function. There is substantial evidence that exercise has benefits for cognitive function in elderly persons. Evidence on the benefits of exercise for cognition (either cognitive improvement or reduced cognitive decline) has been demonstrated through epidemiological studies, meta-analytical studies, and randomized controlled trials.

Although exercise training holds promise for delaying the onset and slowing down the progression of cognitive impairment among elderly persons, most studies utilized aerobic-base exercise with relatively high intensity. High intensity aerobic exercise may not be practical for older people because they are likely to have physical limitations and/or co-morbid diseases.Thus, the effects of other forms of exercise particularly those that are less intense and well suited to elderly conditions should be examined. The moderating factors linking exercise training and cognitive improvement is yet to be further investigated.

Tai Chi, a form of mind-body exercise, is a popular exercise among elderly. Although Tai Chi is considered as an aerobic exercise, the focus of this exercise in elders is not on cardiovascular fitness. It is characterized by slow, gentle motion and emphasized the conscious control of body movements. Several cognitive components including attention and mindfulness engage with physical movements during Tai Chi exercise. Thus, it is expected that Tai Chi exercise would have great benefit on cognition. Most research on Tai Chi has been done in the area of balance and falls. Studies examining the effects of Tai Chi exercise on cognitive function are sparse especially in the population of mild cognitive impairment.

Inclusion Criteria:

1. Diagnosis for MCI based on Petersen's criteria as follows:

   • A self-reported memory complaint, corroborated by an informant interview
   • A score on a standardized memory test rated as 0.5 on Clinical Dementia Rating (CDR)
   • Normal general cognitive function, as determined by a clinician's judgment based on a structured interview with the patient and an informant report and adjusted Thai Mini-Mental State Examination (TMSE) 35
   • No or minimal impairment in activities of daily living (ADLs) or instrumental Activity of Daily Living (IADL), as determined by clinical review with the patients and informant interview
   • Not sufficiently impaired, cognitively and functionally, to meet National Institute of Neurological and Communicative Disorders and Stroke/ Alzheimer's disease and Related Association (NINCDS-ADRDA) criteria for AD, as judged by an experienced AD clinician

2. Presence of cognitive impairment determined by the score on the Montreal Cognitive Assessment (MoCA) lesser than 26

3. Comprehend instructions and willing to participate

Exclusion Criteria:

1. Presence of medical conditions that would be unsafe to exercise
2. Presence of neurological conditions (e.g. Parkinson's disease, Stroke, Multiple Sclerosis)
3. Presence of depressive symptoms, defined by the Geriatric Depression Scale (GDS)-Thai version 36
4. Presence of acute or/and chronic disease that could not be controlled (e.g. Arthritis, Asthma, Hypertension, Diabetes mellitus, Coronary artery disease)
5. Taking alcohol 6 hr before testing or using drug regimens that affect performance such as sedative and antidepressant.
6. Exercise regularly (40-50 min/day at least 3 days/week)