Walking in high-risk settings: do older adults still prioritize gait when distracted by a cognitive task?

When a cognitive and a motor task like walking or keeping one's balance are performed concurrently, performance usually deteriorates. Older adults have often been shown to prioritize their motor performance in such dual-task situations, possibly to protect themselves from falls. The current study investigates whether these prioritization behaviors can still be observed when several challenges are combined. Younger (20-30 years old) and older adults (60-70 years old; n = 24 in each group) were asked to walk through virtual environments with and without a cognitive load (3-back task). Walking difficulty was increased by walking on an elevated surface or on a narrow as opposed to a broad track, or both. Walking instructions emphasized speed and accuracy (avoiding missteps). No instruction was given concerning which performance dimension should be prioritized during dual-task trials. Participants decreased their 3-back performance while walking. Younger adults maintained their walking speed on elevated surfaces and were able to keep the number of missteps low, even when walking on a narrow track while performing the cognitive task. Older adults increased their walking speed on elevated relative to even surfaces and committed more missteps under cognitive load. Results suggest that task prioritization might fail in healthy older adults if several challenges are combined in high-risk settings.