Effectiveness of the KENKOJISEICHI local revitalization system on cognitive function change in older adults with mild cognitive impairment: study protocol for a randomized controlled trial

The KENKOJISEICHI group will participate in classes focusing on 101 outdoor behaviors, including 28 physical activities, 29 intellectual activities, and 44 social activities; a small group gathering meeting will also be available. Locations that meet at least two of the following five examination requirements will be certified as healthy places: (1) places where KENKOJISEICHI group members can participate as they choose and can carry out activities with a purpose, (2) places where they can participate lightly, (3) places where people can interact with other people in the community, (4) places where the chosen activity can be performed, and (5) places where relaxation and relief can be realized. Nevertheless, a site that is used for political or religious activities or for the purpose of promoting these activities will not be recognized for KENKOUJISECHI purposes.

Social activities will be conducted in a community network and will include events such as traditional and health festivals, as well as visiting a cafeteria, drug store, shopping mall, temple, sightseeing spot, senior’s club, or variety store. Cognitive activities will include visiting a library, singing karaoke, playing the Japanese game Go, reminiscing (life review), arts and crafts, doing calligraphy, video impression, creating stamp art, and visiting an art museum. Physical activities will include Tai Chi, machine studio, indoor golf, walking, muscle strength training, stretch, hula dance, traditional dance, boccia, and social dance.

The intervention program consists of participating in social (16 times), intellectual (16 times), and physical activities (16 times). The forty-eight 90-minute sessions take place twice per week over 24 weeks and include a 15-minute condition check and stretching; 60 minutes of social activity, intellectual activity, or PA; and 15 minutes to write a report, provide impressions, and discuss the upcoming schedule. Participants will be divided into nine groups with two to four participants and two to three staff members in each group. The staff will manage the schedule, check health during participation, and prepare reports. This program focuses on improving outdoor behaviors and communication; therefore, it was designed to be simple and performed at any location in order to facilitate long-term adherence for all participants.

Participants will choose their next KENKOJISEICHI location by talking with the staff and through group-based activities (Table 1). The participants will record their impressions about the content of each day’s activity. Then, staff will write a brief activity report and note feedback from participants.

Participants in the educational control group will attend two 90-minute educational classes during the 6-month trial period. The classes will taught by experts on topics considered less likely to influence cognition and PA (e.g., nutrition, pain, and oral care).

The primary outcome measure is cognitive function at the 6-month postintervention assessment. Cognitive function will be assessed using the NCGG-FAT [19, 20], a multidimensional neurocognitive test, to assess memory (word list memory-I: immediate recognition; word list memory-II: delayed recall), attention and executive function (electronic tablet version of the Trail Making Test A and B), processing speed (electronic tablet version of the Digit Symbol Substitution Test), and visuospatial function (original version of the NCGG-FAT). High test-retest reliability and moderate to high validity were confirmed in community-dwelling older adults for all task components of the NCGG-FAT.

Secondary outcomes will be brain and hippocampal volume, mental status, and depressive symptoms, which can potentially explain the mechanisms of the effects of the KENKOJISEICHI activities on the primary outcome. Whole-brain and hippocampal volume will be determined using a 3-T magnetic resonance imaging system (TM Trio; Siemens Healthcare, Erlangen, Germany). Three-dimensional volumetric acquisition of T1-weighted gradient-echo sequences will be performed to produce a gapless series of thin sagittal sections using a magnetization preparation rapid-acquisition gradient-echo sequence (inversion time [TI] 800 milliseconds, repetition time [TR] 1800 milliseconds, echo time [TE] 1.99 milliseconds, and 1.1-mm slice thickness). Axial T2-weighted spin-echo images (TR 4200 milliseconds, TE 89.0 milliseconds, and 5.0-mm slice thickness) and axial fluid-attenuated inversion recovery images (TI 2500 milliseconds, TR 9000 milliseconds, TE 100 milliseconds, and 5-mm slice thickness) will then be obtained for diagnosis.

Depressive symptoms will be measured using the Geriatric Depression Scale [21], which is a self-report screening tool developed to detect depression in older adults. The responses to the 15-item questionnaire will be scored, with scores of 0–4 defined as normal, 5–10 as mildly depressed, and 11–15 as severely depressed [22, 23]. A total score ≥ 5 points is considered to indicate depressive symptoms.

Quantity of talk will be measured using a biosensor device (Silmee™W20; TDK Co., Ltd., Chiba, Japan) for continuous monitoring of the volume of talk. All of the participants will be asked to wear the biosensor over their right wrist for 14 days following their examination while outdoors, except while swimming or bathing, and to maintain their usual activities.

PA will be measured using a triaxial accelerometer (modified HW-100; Kao Co., Ltd., Tokyo, Japan) for continuous monitoring of the intensity of PA. We will calculate parametric values, including the weekly average, for the daily amounts of light-intensity PA (1.5–2.9 metabolic equivalents [METs]) and moderate to vigorous PA (≥ 3.0 METs). The data will be recorded in 4-second epochs for up to 1 day and will be collected using the KAO system installed at the KENKOJISEICHI. The display of the accelerometer will be blinded. For inclusion in the present study, a valid day will be defined as a day in which the accelerometer is worn for ≥ 10 hours, with a total wear duration ≥ 7 days.

Participants in our study will perform three physical function tests. First, the Short Physical Performance Battery is used to measure balance, gait speed, and lower extremity strength [24]. The total score as well as each component score is related to the degree of disability, and these scores are strongly associated with mortality and hospital admission. Second, in the trail walking test, flags are installed randomly at each of 15 positions [25]. Third, handgrip strength will be measured using a handheld dynamometer (T.K.K. 5401 GRIP D; Takei Scientific Instruments, Tokyo, Japan), with participants in a standing position with their arms hanging naturally at their sides [26].

The participants will complete a self-report health status interview to provide information on a variety of health-related factors. PA will be measured using the International Physical Activity Questionnaire [27]. Low, moderate, and high levels of PA will be calculated on the basis of METs for different activities. Basic health will be measured using the Kihon Checklist (KCL) [28]. The KCL consists of 25 items with 6 subscales, including activities of daily living (5 items), physical ability (5 items), nutrition (2 items), oral condition (3 items), seclusion (2 items), forgetfulness (3 items), and mind (5 items). Life-space mobility will be measured with the LSA [29], which is used to obtain a score based on the reported distance traveled during the 4 weeks preceding assessment. Sleep quality will be evaluated using the Pittsburgh Sleep Quality Index [30], which consists of 19 items that produce a global sleep quality score and scores for 7 components (sleep quality, latency, duration, disturbance, habitual sleep efficiency, use of soporific medication, and daytime dysfunction). Simple nutritional evaluation tools will include the Short Nutritional Assessment Questionnaire [31], which contains 15 items for hospitalized patients and has some items that are most useful for outpatient weight loss, loss of appetite, and use of nutritional supplements and/or tube feeding. Mental health will be measured with the Japanese version of the five-item World Health Organization Well-Being Index, which is a short global rating scale used to measure subjective well-being [32]. The respondent is asked to rate how well each of the five statements applies to him or her when considering the last 14 days. Instrumental activities of daily living evaluation tools will include the Japan Science and Technology Agency Index of Competence (JST-IC) [33]. The JST-IC is a modified version of the Tokyo Metropolitan Institute of Gerontology Index of Competence. Cognitive health will be assessed using subjective memory complaints (SMCs) [34]. SMCs combine the Cambridge Mental Disorders of the Elderly Examination questionnaire and the SMC scale. Hearing screening will be conducted using the Hearing Handicap Inventory for the Elderly–Screening Version (HHIE-S) [35]. The HHIE-S is a ten-item questionnaire developed to assess how an individual perceives the social and emotional effects of hearing loss.

Health-related factors that will be assessed through questionnaires will include blood pressure, medical history, medications, education, smoking status, alcohol intake, whether living alone, outing frequency, self-health status, falls, fall-related injuries, fear of falling, urinary incontinence, habitual exercise, mobility limitations, use of a hearing aid, vision, use of a walking aid, pain, talking, talking time, outdoor self-efficacy, and outdoor social support.

Body composition and anthropometric measurements will include body weight, and fat and muscle volumes will be measured using multifrequency bioelectrical impedance analysis (MC-980A; TANITA Inc., Tokyo, Japan). Height will also be measured.