TY - JOUR
T1 - Balance and gait represent independent domains of mobility in Parkinson disease
AU - Horak, Fay B.
AU - Mancini, Martina
AU - Carlson-Kuhta, Patricia
AU - Nutt, John G.
AU - Salarian, Arash
N1 - Publisher Copyright:
© 2016 American Physical Therapy Association.
PY - 2016/9
Y1 - 2016/9
N2 - Background. The Instrumented Stand and Walk (ISAW) test, which includes 30 seconds of stance, step initiation, gait, and turning, results in many objective balance and gait metrics from body-worn inertial sensors. However, it is not clear which metrics provide independent information about mobility. Objective. It was hypothesized that balance and gait represent several independent domains of mobility and that not all domains would be abnormal in individuals with Parkinson disease (PD) or would change with levodopa therapy. Design. This was a cross-sectional study. Methods. A factor analysis approach was used to identify independent measures of mobility extracted from the ISAW in 100 participants with PD and 21 control participants. First, a covariance analysis showed that postural sway measures were independent of gait measures. Then, the factor analysis revealed 6 independent factors (mobility domains: sway area, sway frequency, arm swing asymmetry, trunk motion during gait, gait speed, and cadence) that accounted for 87% of the variance of performance across participants. Results. Sway area, gait speed, and trunk motion differed between the PD group in the off-levodopa state and the control group, but sway frequency (but not sway area) differed between the PD group in the off-levodopa state and the control group. Four of the 6 factors changed significantly with levodopa (off to on): sway area, sway frequency, trunk motion during gait, and cadence. When participants were on levodopa, the sway area increased compared with off levodopa, becoming more abnormal, whereas the other 3 significant metrics moved toward, but did not reach, the healthy control values. Limitations. Exploratory factor analysis was limited to the PD population. Conclusions. The different sensitivity various balance and gait domains to PD and to levodopa also support neural control of at least 6 independent mobility domains, each of which warrants clinical assessment for impairments in mobility.
AB - Background. The Instrumented Stand and Walk (ISAW) test, which includes 30 seconds of stance, step initiation, gait, and turning, results in many objective balance and gait metrics from body-worn inertial sensors. However, it is not clear which metrics provide independent information about mobility. Objective. It was hypothesized that balance and gait represent several independent domains of mobility and that not all domains would be abnormal in individuals with Parkinson disease (PD) or would change with levodopa therapy. Design. This was a cross-sectional study. Methods. A factor analysis approach was used to identify independent measures of mobility extracted from the ISAW in 100 participants with PD and 21 control participants. First, a covariance analysis showed that postural sway measures were independent of gait measures. Then, the factor analysis revealed 6 independent factors (mobility domains: sway area, sway frequency, arm swing asymmetry, trunk motion during gait, gait speed, and cadence) that accounted for 87% of the variance of performance across participants. Results. Sway area, gait speed, and trunk motion differed between the PD group in the off-levodopa state and the control group, but sway frequency (but not sway area) differed between the PD group in the off-levodopa state and the control group. Four of the 6 factors changed significantly with levodopa (off to on): sway area, sway frequency, trunk motion during gait, and cadence. When participants were on levodopa, the sway area increased compared with off levodopa, becoming more abnormal, whereas the other 3 significant metrics moved toward, but did not reach, the healthy control values. Limitations. Exploratory factor analysis was limited to the PD population. Conclusions. The different sensitivity various balance and gait domains to PD and to levodopa also support neural control of at least 6 independent mobility domains, each of which warrants clinical assessment for impairments in mobility.
UR - http://www.scopus.com/inward/record.url?scp=84985952043&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84985952043&partnerID=8YFLogxK
U2 - 10.2522/ptj.20150580
DO - 10.2522/ptj.20150580
M3 - Article
C2 - 27034314
AN - SCOPUS:84985952043
SN - 0031-9023
VL - 96
SP - 1364
EP - 1371
JO - Physical therapy
JF - Physical therapy
IS - 9
ER -