Gait speed, handgrip strength, and cognitive impairment among older women - A multistate analysis

Cognitive impairment imposes substantial psychological, emotional, and economic burdens on affected individuals, families and society. A better understanding of potentially modifiable risk factors that may be used in the prevention of cognitive impairment is therefore a high priority in aging research.

This study included 9268 community-dwelling women aged 65 years or older from the Study of Osteoporotic Fractures launched between 1986 and 1988 in the US. Participants were followed for 20 years. Modified Mini-Mental State Examination (m-MMSE) was administered up to 6 times. Six updated measurements of gait speed and handgrip strength at the same visit time when m-MMSE was administered were used. The m-MMSE score was used to define cognitive impairment states (normal, mild, and severe impairment). A multi-state model (MSM) was used to estimate the transitions between different states of cognitive function.

Faster gait speed (one unit increase of meter/s) was associated with lower risk of transition from cognitively normal status to mild cognitive impairment (HR = 0.50, 95 % CI: 0.37-0.67), and from mild impairment to severe impairment (HR = 0.52, 95 % CI: 0.37-0.72). Higher gait speed was associated with increased risk of cognitive transition from severe impairment to mild impairment (HR = 2.56 95 % CI: 0.97-6.77), although the result did not reach statistical significance. Similarly, we observed greater handgrip strength (per kg increase) was associated with lower risk of transition of cognitive status from normal to mild impairment (HR = 0.96 95 % CI: 0.95-0.97), and from mild to severe impairment (HR = 0.98, 95 % CI: 0.96-0.99). Greater handgrip strength was associated with increased risk of cognitive transition from severe to mild cognitive impairment (HR = 1.05, 95 % CI: 1.01-1.09). In addition, we also observed that both faster gait speed and greater handgrip strength were associated with lower risk of transitions from normal or mild cognitive impairment status to death.

Our results confirmed that screening for slow gait speed or weak handgrip strength may be useful for identifying older adults at risk for cognitive decline when they are still cognitively normal or only mildly impaired. Exercise programs to improve gait speed and muscle strength may delay or prevent transitions into cognitive impairment in older adults.