A neuromechanical model characterizing the motor planning and posture control in the voluntary lean in Parkinson's disease.
Niromand Jasimi Zindashti, Zahra Rahmati, Abolfazl Mohebbi and 1 others
PMID 38360634WHAT IT FOUND
PD patients lean slower and with stiffer ankles, especially backward.
They also make smaller preparatory movements before leaning. These model parameters correlate with clinical scores like UPDRS and Functional Reach, offering a way to quantify specific balance deficits.
Key findings
01PD patients showed significantly higher feedback control gains (stiffer ankle strategy) than healthy subjects in all directions, particularly when leaning backward.
02PD patients exhibited significantly lower feedforward control gains (smaller anticipatory postural adjustments) compared to healthy subjects.
03Temporal parameters like reaction and reaching times were significantly longer in PD patients, except for anticipatory postural adjustment duration which showed no difference.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
The healthy control group was not gender-balanced (all male), while the PD group had both men and women. The PD patients were in early-to-moderate stages of disease (Hoehn and Yahr 1-3), so results may not apply to more advanced stages. This is a modeling study; the parameters are derived from a specific mathematical framework and not directly observable clinical measures.
Declared interests
The authors declare no competing interests. The study was approved by the Iran University of Medical Science ethics committee.
The easy way to misread this
Do not interpret the model parameters (feedback/feedforward gains) as direct physiological measurements like EMG or stiffness. They are abstract control variables derived from the mathematical model that fit the observed center-of-pressure data. Also, the correlation with clinical scores does not prove causation or that these specific parameters are the sole cause of the balance deficits.