Correspondence
Tai Chi for Patients with Parkinson's Disease
N Engl J Med 2012; 366:1737-1738May 3, 2012DOI: 10.1056/NEJMc1202921
- Article
To the Editor:
The article by Li et al. (Feb. 9 issue)1 reported that tai chi was successful in improving various functional outcomes in patients with mild-to-moderate Parkinson's disease, as compared with conventional physical exercises (resistance training and stretching). However, that success might be due to placebo effects rather than to the specific efficacy of tai chi itself. Since this study did not use a double-blind study protocol, participants were aware of their intervention assignments, possibly allowing their beliefs and expectations to bias treatment outcomes. Indeed, Parkinson's disease is one of a number of conditions that are particularly subject to the influence of placebo effects.2 Tai chi is definitely more than a mere set of body movements. At the core of tai chi is a unique theory based on ancient Chinese culture about the value of moving vital energy, or qi, throughout the body. Tai chi can hardly be practiced in the absence of its cultural underpinnings. In fact, performing tai chi can be considered to be just a “healing ritual [that] creates a receptive person susceptible to the influences of authoritative culturally sanctioned powers,”3 thus producing robust placebo responses.
Tao Liu, M.D.
Jilin University, Changchun, China
cctaoliu@hotmail.com Lixing Lao, Ph.D.
University of Maryland School of Medicine, Baltimore, MDNo potential conflict of interest relevant to this letter was reported.
3 References1
Li F ,Harmer P ,Fitzgerald K , et al. Tai chi and postural stability in patients with Parkinson's disease. N Engl J Med 2012;366:511-519
Free Full Text | Web of Science | Medline2
de la Fuente-Fernandez R ,Ruth TJ ,Sossi V ,Schulzer M ,Calne DB ,Stoessl AJ . Expectation and dopamine release: mechanism of the placebo effect in Parkinson's disease. Science 2001;293:1164-1166
CrossRef | Web of Science | Medline3
Kaptchuk TJ . Placebo studies and ritual theory: a comparative analysis of Navajo, acupuncture and biomedical healing. Philos Trans R Soc Lond B Biol Sci 2011;366:1849-1858
CrossRef | Web of Science | Medline
To the Editor:
In their study of tai chi in Parkinson's disease, Li et al. used the Unified Parkinson's Disease Rating Scale (UPDRS) III, which consists of 14 items scored from 0 to 4. Several of these items have right and left scores, resulting in a possible range of 0 to 108.1 However, the authors incorrectly used only one score for each item, causing their methodology to be flawed. In contrast to the established, validated scoring of the UPDRS III, Li et al. used this scale to assign motor ratings that are not validated or standard. Their application of the UPDRS amplifies the contribution of midline UPDRS III ratings, including balance and gait, thereby potentially biasing their results in favor of their hypothesis. If the data were in fact collected correctly but reported incorrectly, we would like the authors to present the correct data and repeat their statistical analysis. The implication of a treatment-related impact on the UPDRS III scores suggests an overall effect on parkinsonism — a conclusion that is unwarranted on the basis of this analysis. It is critical for studies of innovative therapies in Parkinson's disease to present findings in the context of previously published findings.
Daniel M. Corcos, Ph.D.
University of Illinois at Chicago, Chicago, IL
dcorcos@uic.edu Cynthia L. Comella, M.D.
Christopher G. Goetz, M.D.
Rush University Medical Center, Chicago, ILNo potential conflict of interest relevant to this letter was reported.
1 ReferenceAuthor/Editor Response
Liu and Lao raise the question of a potential placebo effect owing to the purported lack of a double-blind design in our study. We believe that our research protocol made it unlikely that this was the case. First, no assessors were aware of group allocation. Also, participants were informed that the study would be comparing three different exercises and that they would be randomly assigned to a group. Although participants were obviously aware of which group they were in (as is the case in virtually all behavior-based interventions), they were unaware of the study hypotheses. Therefore, it is not likely that a differential expectation of improvement based on group assignment would bias the results. As concluded by de la Fuente-Fernández et al.,1 under such circumstances, results are not compromised by the possibility of a placebo effect. The argument by Liu and Lao that the Chinese cultural underpinnings of tai chi drive the proposed placebo effect is moot, since our training protocol does not involve any such cultural elements. Thus, it is hardly scientifically plausible that the outcomes were influenced by the placebo mechanism they propose.
In response to Corcos et al. on our use of the UPDRS III: we disagree with the assertion that our study “methodology is flawed.” The effect of any disagreement concerning our use of the scale (which was an adjunct secondary outcome) must rightly be restricted to the interpretation of any changes in scale scores, which, even if omitted, would not affect the overall findings of the study. With regard to the specific criticism, our scoring method was based on the face validity of individual items and on our a priori central interest in examining the effect of tai chi on changes in axial symptoms (i.e., postural instability and gait). Since this approach was applied with the use of a standardized protocol in all groups, it is unclear how it would bias the results in favor of our hypotheses. Moreover, this modification is not uncommon in research on Parkinson's disease.2,3
Fuzhong Li, Ph.D.
Oregon Research Institute, Eugene, OR
fuzhongl@ori.org Peter Harmer, Ph.D., M.P.H.
Willamette University, Salem, ORSince publication of their article, the authors report no further potential conflict of interest.
3 References1
de la Fuente-Fernandez R ,Ruth TJ ,Sossi V ,Schulzer M ,Calne DB ,Stoessl AJ . Expectation and dopamine release: mechanism of the placebo effect in Parkinson's disease. Science 2001;293:1164-1166
CrossRef | Web of Science | Medline2
Brusse KJ ,Zimdars S ,Zalewski K ,Steffen TM . Testing functional performance in people with Parkinson disease. Phys Ther 2005;85:134-141
Web of Science | Medline3
Frazzitta G ,Bertotti G ,Riboldazzi G , et al. Effectiveness of intensive inpatient rehabilitation treatment on disease progression in Parkinson's patients: a randomized controlled trial with 1-year follow-up. Neurorehabil Neural Repair 2012;26:144-150
CrossRef | Web of Science | Medline
- Citing Articles (1)
Citing Articles
1
Giselle M Petzinger, Beth E Fisher, Sarah McEwen, Jeff A Beeler, John P Walsh, Michael W Jakowec. (2013) Exercise-enhanced neuroplasticity targeting motor and cognitive circuitry in Parkinson's disease. The Lancet Neurology 12:7, 716-726
