Advances in dementia research have shifted attention towards earlier stages in the natural history, such as Mild Cognitive Impairment. The current gold standard outcome measure, the Alzheimer’s Disease Assessment Scale-Cognitive Subscale, is not optimally responsive to changes in pre-dementia populations. Modifications to scoring methodology and content have improved the measurement performance of the ADAS-Cog. However, no published modifications have addressed a second key shift in the field towards understanding motor function as an important component of dementia and pre-dementia syndromes. This thesis used a Pooled Index approach to combine an ADAS-Cog-Proxy measure with assessments of gait velocity and dual-task cost. The responsiveness of the PI to baseline discrimination between older adults with normal cognition, Subjective Cognitive Impairment, and MCI was similar to the ADAS-Cog-Proxy. The PI demonstrated greater responsiveness than the ADAS-Cog-Proxy to change over 6mo. and 48mo., but not 36mo. of follow-up. Overall, motor function assessments improve ADAS-Cog responsiveness