Study design and participants
The study was designed as a two-arm trial to examine the effects of a six-month mindfulness-based Tai Chi intervention versus treatment as usual (TAU). It was approved by the ethics committee of the Bavarian Medical Association, Germany, and all participants provided written informed consent. Participants were recruited from the Department of Neurology, Klinikum Bayreuth. Invitations were given orally or via mail to patients who were or had been in out-patient care. Additionally, study invitations were distributed via local support groups. Information about clinical characteristics was extracted from patients’ files held by the Department of Neurology. Inclusion criteria were a diagnosis of any MS type, being able to walk without a walking aid, an Expanded Disability Status Scale (EDSS) score < 5, and being relapse-free for the past four weeks. Severe cognitive impairment which would interfere with the ability to take part in weekly Tai Chi classes was ruled out, based on reports of the neurological examinations in patients’ files.
Between December 2010 and November 2011, the files of a total of 400 MS patients were screened for eligibility criteria. Since the site of the study (Klinikum Bayreuth) is located in a rural area of Germany, a substantial portion of these candidates (approximately 250) were discarded beforehand due to the distance of their home to the study site, which made a weekly appearance impossible. Out of the remaining candidates, 38 met inclusion criteria and were willing to participate in the study. Outcome measures were assessed during a patient visit at baseline and following an interval of six months. In this context, all patients participated in assessments addressing balance, fatigue, depression, and quality of life. Potential alterations in balance and coordination were defined as primary endpoints, alterations in fatigue, depression and quality of life as secondary endpoints of the study. During the six-months interval between pre (baseline) and post assessments, 15 patients received structured Tai Chi training (Tai Chi group), and 17 patients received treatment as usual (TAU group), i.e. they were instructed to consult their medical professionals as they usually would. In a pilot phase, implemented with the intention to raise awareness about the possibility to participate in Tai Chi courses in the study centre, members of the latter group had previously taken part in Tai Chi classes. However, during the six-months interval, members of this group did not participate in a structured intervention. Due to the length of the intervention and to enable patients to participate regularly, group assignment occurred based on patients’ availability for the weekday on which the Tai Chi course took place.
Six Patients from the Tai Chi group withdrew from the study due to time issues (N = 5) and health problems (N = 1) and were lost to follow-up. Consequently a total of 32 patients was included in the final analysis (Tai Chi N = 15; TAU N = 17). As indicated in Table
1, there were no significant differences with regards to basic demographics between the Tai Chi group and the TAU group. Further, there were no clinical differences regarding MS course, disease duration and MS treatment. However, the EDSS was elevated in the TAU group (range: 1–4.5, median = 4), relative to the Tai Chi group (range: 1–4, median = 2). Adherence varied between 15 and 44 (median = 30) attended classes out of 50 classes offered in total.
Table 1
Demographics, clinical information, health behavior
Demographics
| | | | | | |
Age M (SD) | 43.6 | (8.0) | 42.6 | (9.4) | 0.32a
| 0.753 |
Female sex, n (%) | 12 | (71) | 10 | (67) | 0.06b
| 0.811 |
Health Behavior
| | | | | | |
Tobacco users, n (%) | 2 | (12) | 3 | (20) | 0.42b
| 0.645 |
Body Mass Index, M (SD) | 25.5 | (5.5) | 24.2 | (3.7) | 0.79a
| 0.438 |
Phys. activity/week, n (%) | | | | | | |
< 1x | 6 | (35) | 2 | (13) | 0.17b
| 0.338 |
1-2x | 6 | (35) | 8 | (53) |
> 3x | 5 | (30) | 5 | (33) |
Clinical Information
| | | | | | |
MS course, n (%) | | | | | | |
Relapsing-remitting | 13 | (77) | 14 | (93) | 4.93b
| 0.085 |
Secondary progressive | 4 | (24) | 0 | (0) |
Clinically isolated syndrome | 0 | (0) | 1 | (7) |
MS Duration in years, M (SD) | 7.8 | (6.8) | 6.0 | (4.7) | 0.86a
| 0.395 |
MS treatment, n (%) | | | | | | |
Yes | 16 | (94) | 12 | (80) | 0.45b
| 0.228 |
Assessment of balance and coordination
An established balance test, comprising 14 tasks with an increasing level of difficulty, including both static and dynamic balance was utilized [
45]. It included a series of one leg stances in different conditions as well as walking across a wooden board in different conditions (forwards, backwards, including turns). The test was previously shown to display sufficient metric qualities (test-retest reliability: r = .78, Chronbach’s alpha = .92) [
45]. In this context, its convergent validity was also shown referring to posturographic measures [
45].
Additionally, a coordination test was implemented, comprising 10 tasks with an increasing level of difficulty [
45]. As was the case for the balance test, the coordination test was previously shown to involve sufficient metric properties (test-retest reliability: r = .60, Chronbach’s alpha = .72) [
45].
In both tests, each task achieved equalled one point, accumulating to a maximum of 14 points in the balance test and 10 points in the coordination test. A detailed description of both tests is provided in Additional file
2: Supplement 2. To our knowledge, the tests have not been used in MS previously. However, they were developed for functional evaluation of patients during neurologic rehabilitation [
45]. Since the tests were designed to cover a broad spectrum of ability/disability within ambulatory patients, they may be regarded as particularly suitable for MS patients with considerable variance in motoric deficits.
Assessment of depression, fatigue and life satisfaction
Additionally, self-reports measures in the domains depression, fatigue and life satisfaction were included. For the assessment of depressive symptoms, a 15-item questionnaire was used (Allgemeine Depressionskala, ADS-K; English: Center for Epidemiological Studies Depression Scale, CES-D); [
46]), which addresses the severity of depressive symptoms during the last two weeks. Items are rated on a scale from 0–3 and the sum of all items represents the depression parameter. Further, the Fatigue Scale of Motor and Cognitive Functions (FSMC [
47]) was administered, which consists of 20 items, scored on a scale from 1–5, and accumulating to a maximum score of 80 points. The Questionnaire of Life Satisfaction (QLS [
48]) consists of 6 domains, including health, finances, leisure time, self, sexuality and friends, comprising 7 items each, on a 1–7 rating scale, accumulating to a maximum score of 420 points.
Tai Chi intervention
A structured, compact Tai Chi program was developed based on the Yang-style 10-form (see Additional file
1: Supplement 1 for details and Martin [
49] or Sinclair [
50] for a video link). Exercises were structured so that during each session of the course, the same essential elements were repeated. The advantage of this design was that patients who missed out on an occasion could rejoin the training without difficulties. Further, continuously repeating the exercises may be regarded as supportive for a long-term learning process and automaticity, potentially fostering neuroplasticity [
13]. The intervention was centre-based and did not include home assignments. The Tai Chi instructor was a highly trained exercise therapist with 4 years of Tai Chi experience. No classes were cancelled and no adverse events were noted.
Throughout the intervention period of six months, weekly sessions of 90 minutes duration took place. During the first month of the course, the Tai Chi form was played 4–5 times per session. A break of a few minutes during which participants could relax and ask questions occurred after each completion of the form. During the consecutive 5 months the form was played 6–8 times per session. In this case, breaks usually occurred after two completions of the form, respectively, albeit they were not always necessary or enforced. The increase in repetitions following the first month was attributable to arising automaticity. In context of the relation between Tai Chi training and mindfulness (Figure
1), this arising automaticity may be associated with an attentional shift from an external focus (imitating the form) to an internal focus (e.g. bodily sensations, breathing). On the occasion with the highest amount of repetitions without a break, 8 repetitions were completed. In general, the instructor organized the class with respect to the energy level and current capability of participants.
Statistical analysis
Scores on all parameters were normally distributed according to Saphiro-Wilk tests (all p-values > 0.05). Differences in outcome parameters between the Tai Chi group and the TAU group were assessed by a two-way repeated measures ANOVA with the within-subjects factor Time (pre vs. post) and the between-subjects factor Group (Tai Chi vs. TAU), separately for each parameter. Post-hoc comparisons were conducted via Bonferroni-corrected two-sided t-tests.
To ensure systematic progression of variance across pre and post measures, in a secondary analysis, test-retest reliability was determined. To this end, Pearson correlations were computed for each test parameter between values obtained at pre and post assessments.