High blood pressure and poor cognitive function are two common health problems among older adults in the United States. They are also closely related because high blood pressure may lead to negative changes in brain structure and function such as poor brain blood flow that can cause poor cognitive function. Executive function is one type of cognitive function that let people plan and perform difficult tasks. It is commonly damaged by high blood pressure. It is also very important for older adults because they need good executive function to live on their own. Tai Chi is a good exercise option for older adults because it is safe, fun, and social. Research studies show that Tai Chi can reduce blood pressure and improve cognitive function, especially executive function. However, researchers do know if these heart and brain health benefits of Tai Chi are connected.

In the ACTION study, researchers will first measure how a single session of Tai Chi followed by a 12-week online Tai Chi program with easy movements changes blood pressure and cognitive function, focusing on executive function. Then, researchers will test if these changes in heart and brain health are connected, and if they are connected through the changes in brain structure and function. Both the single session and 12-week online Tai Chi program will be practiced by a group of older adults with high blood pressure and normal cognitive function. They will be new to Tai Chi and not exercising regularly.

The hypotheses of the ACTION study are that practicing Tai Chi is good for the heart and brain of older adults with high blood pressure. Specifically, relaxing Tai Chi with gentle movements will reduce blood pressure, and thereby improve cognitive function, particularly executive function.

Hypertension is a major cardiovascular disease risk factor affecting >70% older adults in the United States. It is also a major contributor to cognitive impairment and dementia that affect over 8 million US older adults. Hypertension can cause deteriorations in brain structure and function such as reduced cerebral blood flow, leading to various types of cognitive dysfunction with declines in executive function being the most common. Of note, executive function is a strong predictor of older adults' ability to live independently in the community. Meta-analyses showed that Tai Chi reduces blood pressure (BP) by 12-15 mmHg for systolic BP and 4-6 mmHg for diastolic BP, and improves cognitive function with an effect size of 0.5 for global cognitive function and 0.9 for executive function. Surprisingly, no study has investigated the relationship between the heart and brain health benefits of Tai Chi among older adults with hypertension.

The primary purposes and hypotheses are presented below. Of note, investigators will define the changes of BP, cognitive function focusing on executive function, and brain structure and functions in response to the 12-week online Tai Chi intervention as the chronic change (see primary outcomes 1 to 9).

1. To examine the relationship between the BP and cognitive function, focusing on executive function, response to a 12-wk online Tai Chi intervention. Investigators hypothesize that the BP and cognitive function, focusing on executive function, response to a 12-wk online Tai Chi intervention will be positively correlated.
2. To examine changes in measures of brain structure and functions in response to a 12-wk online Tai Chi intervention, and explore their associations with the BP and cognitive function, focusing on executive function, responses to Tai Chi. Investigators hypothesize that the relationship between the BP and cognitive function, focusing on executive function, responses to the 12-wk online Tai Chi intervention is mediated by the changes in brain structure and function.

The secondary purposes are to examine the relationship between the BP and cognitive function, focusing on executive function, response to a single session of Tai Chi exercise. Investigators hypothesize that the BP and cognitive function, focusing on executive function, response to a single session of Tai Chi exercise will be positively correlated. Of note, investigators will define the changes of BP, cognitive function focusing on executive function in response to a single session of Tai Chi exercise as the acute change (see secondary outcomes 1 to 5).

The participants will be randomized to either a Tai Chi (n=10) or control group (n=10). Participants will receive informed consent material and attend live online Q&A sessions. Participants who signed the informed consent form will attend online visits 1 and 2, and in-person visit 3 to complete eligibility screening. For pre-intervention measures, participants will attend online visit 3 and in-person visits 4 and 5. In-person visits 4 and 5 will be in randomized order and include: 1) the Acute Exercise Visit A during which participants will attend a 45-minute Tai Chi exercise session at the local senior center; and 2) the Control and Magnetic Resonance Imaging [MRI] Visit A at the Brain Imaging Research Center [BIRC] at UConn Storrs during which participants will attend a 45-minute sham control session (i.e., watching Tai Chi themed video). A trained, blinded research assistant will: 1) measure resting BP and cognitive function before and after the 45-minute Tai Chi session in the Acute Exercise Visit A and the 45-minute sham control session in the Control and MRI Visit A; and 2) attach participants to a 24-hour ambulatory BP (ABP) monitor at the end of both the Acute Exercise Visit A and the Control and MRI Visit A that will be worn to the next morning. In addition, participants will participate in an 60-minute MRI scanning session at BIRC in the Control and MRI Visit A. The 12-week online Tai Chi intervention will start after in-person visit 5, participants assigned to the Tai Chi group will attend live online Tai Chi sessions led by a certified Tai Chi instructor for 3 sessions/week, 45 minutes/session for 12 weeks. The participants will also practice Tai Chi at home between sessions using instructional video that will be shared with them at the end of each live online Tai Chi session. Meanwhile, participants in the control group will perform only their regular habitual daily activities throughout the 12-week study. After the 12-week intervention period, participants will attend in-person visit 6 (Control and MRI Visit B) at the BIRC with procedures identical to those conducted in in-person visit 4 or 5 (Control and MRI Visit A). Participants will attend in-person visit 7 (Acute Exercise Visit B) at the local senior center with procedures identical to those conducted in in-person visit 4 or 5 (Acute Exercise Visit A).

Inclusion criteria:

• All participants will have established hypertension evidenced by awake ambulatory systolic blood pressure (ASBP)≥130 mmHg or awake ambulatory diastolic blood pressure (ADBP)≥80 or taking antihypertensive medication regardless of the awake ASBP and awake ADBP values. In addition, participants will have blood pressure (BP) within the safe range to exercise evidenced by awake ASBP<145 mmHg and awake ADBP<90 regardless of the use of BP medications.
• For women only, participants need to be postmenopausal evidenced by having experienced >6 consecutive months without menstruation. This is because menstruation could potentially influence BP.
• Participants will be free of Tai Chi practice in the past 12 months
• Participants will, at least, have graduated from high school or have obtained GED.
• Participants will have intact cognitive function evidenced by scoring 25 or higher on the Mini Mental State Examination.
• Participants will be physically inactive as did not exercise for 30 min or more per day at moderate intensity on 3 or more days per week in the past 12 weeks. Subjects will not have physically demanding occupations.
• Participants will consume <2 alcoholic drinks daily because the effects of alcohol may obscure the BP response to exercise.
• Participants will be non-smokers for at least 6 months prior to entry because the effects of tobacco may obscure the BP response to exercise.
• Participants need to have sufficient access to internet and electronic equipment (e.g., laptop, desktop, tablet) to participate in virtual research visits and live online Tai Chi sessions, and email study personnel.

Exclusion criteria:

• Participants will have no contradictions to fully participate in ACTION. They will be excluded if they have: 1) signs or symptoms suggestive of cardiovascular, renal, and metabolic disease; 2) psychiatric and neurological disorders such as general anxiety and depression; 3) body mass index <18.5 kg.m^-2 or >35 Kg·m^-2) orthopedic problems likely to restrict Tai Chi exercise in standing position; 5) contradictions to MRI scans to the brain.
• If the participants has been diagnosed with chronic diseases that require medical clearance to exercise that include cardiovascular, renal, and metabolic disease, the PI and the study medical director will review the participants's medical history and determine if it is safe for him or her to participate in ACTION. If determined unsafe to exercise, the participant will be excluded.
• For participants who have been diagnosed with cancer, only those who have had cancer under remission for 6 months or longer will be considered for inclusion. Otherwise, the participant will be excluded.
• Cancer survivors will be excluded if they: 1) had lung, abdominal surgery, or ostomy within the past 6 months; 2) are currently experiencing ataxia, extreme fatigue, severe nutritional deficiencies, worsening/changing physical condition (i.e., lymphedema exacerbation), bone metastases. For other cancer survivors, the PI and the study medical director will review the participant's medical history and determine if it is safe for him or her to participate in ACTION. If determined unsafe to exercise, the participant will be excluded.
• Participants who have extensive experience with Tai Chi, defined as have practiced Tai Chi for ≥2 sessions/week for ≥3 months continuously, will be excluded.
• Participants who have physically demanding occupations will be excluded.
• Participants acknowledging illicit drug use within the past 5 years will not be recruited.
• Participants taking any medications, except for corticosteroids and hypnotics, should: 1) have been taking the medications for ≥3 months prior to entry; and 2) maintain their routine of taking the medications throughout the study when possible. Otherwise, the participant will be excluded.
• Participants who take corticosteroids and hypnotics as needed will not be recruited because these medications could potentially influence BP and brain blood flow and function.
• Participants taking any nutritional supplements other than a 1-a-day vitamin, cold medications, and herbal supplements would be asked to discontinue these medications before entering the study or be excluded.
• Changes in diet and weight have the potential to obscure and/or augment the influence of our Tai Chi intervention on BP. Participants will be excluded if they are seeking to gain or lose weight or had a weight change of >5 lb in the past 3 months. Investigators will also not recruit subjects unwilling to maintain their habitual diet throughout study participation.