Impaired Sensorimotor Processing During Complex Gait Precedes Behavioral Changes in Middle-aged Adults

Area of Science:

• Neuroscience
• Gerontology
• Biomechanics

Background:

• Gait impairment in older adults is linked to failed compensation for sensory input loss by central neural processes.
• The study hypothesizes that subtle declines in higher cerebral adaptations may exist in middle-aged adults before observable gait issues.

Purpose of the Study:

• To compare metabolic brain activity during complex gait (steering) versus simple gait (straight walking) in young and middle-aged adults.
• To investigate age-related differences in brain activation patterns during demanding locomotion tasks.

Main Methods:

• Positron emission tomography (PET) was used to assess cerebral distribution of [18F]-fluorodeoxyglucose, a marker of brain synaptic activity.
• Seven young adults (24 ± 3 years) and seven middle-aged adults (59 ± 3 years) underwent PET scans during overground straight walking and gait steering.
• Brain metabolic activity was analyzed in relation to walking conditions and age groups.

Main Results:

• Brain regions crucial for gait steering (posterior parietal cortex, superior frontal gyrus, cerebellum) were maintained in middle age.
• Despite similar walking performance, middle-aged adults showed altered brain activity during steering: increased activation in precentral and fusiform gyri.
• Middle-aged adults exhibited reduced deactivation in multisensory cortices (inferior frontal, postcentral, fusiform gyri) and reduced activation in the middle frontal gyrus and cuneus.

Conclusions:

• Preclinical decline in central sensorimotor processing is detectable in middle-aged adults during complex walking tasks.
• These findings suggest that subtle age-related changes in brain function during demanding motor tasks can precede overt gait impairment.