Effects of Fatigue on Balance in Individuals With Parkinson Disease: Influence of Medication and Brain-Derived Neurotrophic Factor Genotype.
Michael Baer, Bradley Klemetson, Diana Scott and 4 others
PMID 29547479WHAT IT FOUND
In 27 people with Parkinson disease, treadmill fatigue did not produce measurable worsening of balance or gait.
Medication state and BDNF genotype did not change that result. Timed Up and Go scores changed after testing.
Key findings
01On the mini-BESTest anticipatory subscale, the study did not find a significant difference for the combined effect of fatigue testing and medication state (p=.131), and it did not find significant differences for fatigue testing alone (p=.942) or medication state alone (p=.698).
02For dynamic balance, Timed Up and Go and Timed Up and Go Cognitive did not show a significant difference for the combined effect of fatigue testing and medication state (ps≥.183), but they did show significant differences over time (ps≤.049).
03BDNF genotype groups did not differ on pre-fatigue gait characteristics (ps≥.111), and they did not differ in response to fatigue across balance domains (ps≥.070).
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study was a pilot with 27 participants, short of the estimated 28 to 33, and the authors state it may have been underpowered for the primary aims. A sample size re-estimation suggested that 114 to 868 participants would be needed to detect the interaction effect. Most participants were Hoehn and Yahr 1 to 2, so the results may not apply to people with Parkinson disease who have more obvious balance impairment. Fatigue was self-rated on a Visual Analogue Scale, and the authors say clinimetric data for this scale in Parkinson disease are insufficient. The treadmill fatigue test may have primed or warmed the lower limbs and postural systems, and the authors suggest cycle ergometry might have been a better fatigue inducer. The authors note that Timed Up and Go times were faster after fatigue, which could reflect priming rather than a true absence of fatigue effects. Testers were blinded to BDNF genotype, but the balance and gait assessors were not blinded to study aims. Missing data were handled with last observation carried forward. BDNF genotype groups were small, with only 2 Met/Met participants, and one participant refused genotyping. The small sample did not allow analysis of Parkinson disease subgroups.
Declared interests
No author conflict-of-interest or funding declaration is provided in the supplied text. The publication type lists non-U.S. government research support.
The easy way to misread this
Do not read the null fatigue result as proof that treadmill exercise to fatigue is safe for every person with Parkinson disease. The study was a small pilot, most participants had mild disease, and the treadmill may have primed balance systems.