Effect of a single dose of diazepam on balance measures in older people.
OBJECTIVE
This study examines the effect of a single dose of diazepam on a spectrum of balance measures in healthy older subjects. The measures include static (postural sway), dynamic (anterior tibialis muscle activation latency), and a complex self-initiated task of balance (functional reach) in addition to neuropsychological tests of attention.


METHODS
A double-blind, two-period, cross-over trial.


METHODS
The community surrounding a university hospital.


METHODS
Community-dwelling, nonsmoking volunteers 65 years of age and older.


METHODS
Measures included response to unexpected perturbation (platform/EMG muscle latency), self-initiated perturbation (functional reach), and a static measure of balance (postural sway). Neurocognitive tests (digital symbol substitution test, card sorting) were included to document the cognitive effect.


RESULTS
Twelve nonsmoking healthy subjects (average age = 70.4 years (66-76 years)) participated. The anterior tibalis muscle latency increased in response to a sudden perturbation with diazepam compared with placebo (TA latency 149 ms vs 142 ms, P < .001). Neurocognitive tests were adversely affected for 90 minutes after diazepam administration compared with placebo (P < .05). Other measures did not demonstrate significant effect of diazepam.


CONCLUSIONS
This is among the first reports showing that benzodiazepines affect neuromuscular processing related to balance control. Increased muscle latency to sudden perturbations may represent an effect of diazepam upon the oligosynaptic spinal reflex distinct from the sedation. Surface electromyography may be a valuable noninvasive tool for future studies of drug effect on balance and falls risk among older people.
Cutson
T M
TM
Geriatric Research, Education, Clinical Center, Durham Veterans' Affairs Medical Center, North Carolina, USA.
Gray
S L
SL
Hughes
M A
MA
Carson
S W
SW
Hanlon
J T
JT
D000368:Aged; D014151:Anti-Anxiety Agents / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D001288:Attention / Q000187:drug effects; D003071:Cognition / Q000187:drug effects; D018592:Cross-Over Studies; D003975:Diazepam / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D004311:Double-Blind Method; D004576:Electromyography / Q000187:drug effects; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D004856:Postural Balance / Q000187:drug effects*
D014151:Anti-Anxiety Agents; D003975:Diazepam