Anticipatory postural responses prior to protective steps are not different in people with PD who do and do not freeze.
D S Peterson, K R Lohse, M Mancini
PMID 29902715WHAT IT FOUND
Anticipatory postural responses before protective steps were not different in people with Parkinson's who freeze compared to those who do not.
Freezing may stem from poor coupling of the response to the step rather than the response size itself.
Key findings
01APA size and the percentage of trials with an APA were not significantly larger in the PD+FOG group compared to the PD-FOG group.
02The relationship between freezing severity and APA size was non-significant for both forward and backward stepping.
03Direction of protective stepping did not impact APA size or frequency.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The sample size was small and no a-priori power calculations were conducted, so the study may be underpowered. Participants had mild to moderate freezing, and actual freezing events during the protective steps were rare. Participants stood with feet together, which may have reduced the size of the postural adjustments and masked group differences.
The easy way to misread this
Do not assume that larger anticipatory postural responses cause freezing of gait. The study found no difference in response size between people who freeze and those who do not, suggesting the issue may lie in how the response is coupled to the step.