The effects of antidepressants on obstructed and unobstructed gait in healthy elderly people

Elderly patients treated with antidepressants for depression are at high risk for injury due to falling. The primary purpose of this study was to determine the effects of amitriptyline, desipramine, and paroxetine on the gait of healthy elderly subjects during unobstructed and obstructed (i.e., stepping over obstacles) gait. Psychomotor and mood tests were also performed.

A randomized, crossover, four-period, double-blind, placebo-controlled laboratory trial was performed. Twelve healthy elderly subjects (average age, 67 years; range, 65-72 years) were tested. Subjects were assigned the three antidepressant drugs or a placebo in a random order. Single doses of amitriptyline 50 mg, desipramine 50 mg, paroxetine 20 mg, or placebo were given 4 hours prior to gait testing. Temporal-distance measures and kinematics of the lower trailing limb (i.e., limb going over obstacle last) were obtained.

Compared with placebo, amitriptyline significantly reduced gait velocity by as much as 8.0% (p = .028), cadence by as much as 4.9% (p = .012), angular velocity of hip flexion by as much as 10.0% (p = .004), and angular velocity of knee flexion by as much as 8.3% (p = 018) during the crossing strides when stepping over obstacles. Except for knee flexion angle, unobstructed gait was not affected. Amitriptyline affected integrative capacity of the central nervous system (CNS) and ability to concentrate as measured by psychomotor and mood tests.

The results for amitriptyline suggest that the subjects slowed their obstacle crossing speeds as a result of reduced CNS integrative capacities. Neither paroxetine nor desipramine significantly affected gait, psychomotor function, or mood.