Table 2. Associations of Gait Speed and Activity Fragmentation With the Hazard of MCI or AD.

Modela	HR (95% CI)	P value
Model 1
Gait speed, per 0.05 m/s	1.073 (1.002-1.149)	.04
Model 2
Activity fragmentation, per 6% (SD)	0.832 (0.563-1.229)	.35
Model 3
Gait speed, per 0.05 m/s	1.097 (1.023-1.176)	.009
Activity fragmentation, per 6% (SD)	1.059 (0.693-1.617)	.79
Interaction between gait speed and activity fragmentation	0.924 (0.868-0.984)	.01

Abbreviations: AD, Alzheimer disease; HR, hazard ratio; MCI, mild cognitive impairment.

^a Includes 520 participants. All Cox proportional hazards regression models were adjusted for baseline age, sex, race and ethnicity, educational level, body mass index, total daily activity, and apolipoprotein E ε4 carrier status. Because models 1 and 3 included gait speed, they were additionally adjusted for height. For interpretation purposes, values of gait speed were scaled to 0.05 m/s, and the original value of gait speed (positive, with higher values indicating better performance) was flipped such that a higher value indicated slower gait and a lower value, faster. Values of activity fragmentation were standardized z scores (mean [SD], 27% [6%]).