Cognitive motor interference during dual-task gait in essential tremor.
BACKGROUND
Functional ambulation requires concurrent performance of motor and cognitive tasks, which may create interference (degraded performance) in either or both tasks. People with essential tremor (ET) demonstrate impairments in gait and cognitive function. In this study we examined the extent of interference between gait and cognition in people with ET and controls during dual-task gait.


METHODS
We tested 62 controls and 151 ET participants (age range: 72-102). ET participants were divided into two groups based on median score on the modified Mini Mental State Examination. Participants walked at their preferred speed, and performed a verbal fluency task while walking. We analyzed gait velocity, cadence, stride length, double support time, stride time, step width, step time difference, coefficient of variation (CV) of stride time and stride length.


RESULTS
Verbal fluency performance during gait was similar across groups (p=0.68). Velocity, cadence and stride length were lowest whereas step time difference (p=0.003), double support time (p=0.009), stride time (p=0.002) and stride time CV (p=0.007) were highest for ET participants with lower cognitive scores (ETp-LCS), compared with ET participants with higher cognitive scores (ETp-HCS) and controls. ETp-LCS demonstrated greatest interference for double support time (p=0.005), step time difference (p=0.013) and stride time coefficient of variation (p=0.03).


CONCLUSIONS
ETp-LCS demonstrated high levels of cognitive motor interference. Gait impairments during complex tasks may increase risk for falls for this subgroup and underscore the importance of clinical assessment of gait under simple and dual-task conditions.
Program in Physical Therapy and G.H. Sergievsky Center, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA. akr7@columbia.edu
Ashwini K
AK
Rao
Jasim
J
Uddin
Arthur
A
Gillman
Elan D
ED
Louis
D000368:Aged; D000369:Aged, 80 and over; D001288:Attention; D016022:Case-Control Studies; D003071:Cognition; D003072:Cognition Disorders / Q000150:complications / Q000503:physiopathology*; D020329:Essential Tremor / Q000150:complications / Q000503:physiopathology*; D005260:Female; D005684:Gait; D020233:Gait Disorders, Neurologic / Q000150:complications / Q000503:physiopathology*; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D011597:Psychomotor Performance
Cognitive-motor interference; Dual-task; Essential tremor; Gait