Motor dysfunction in mildly demented AD individuals without extrapyramidalsigns

Background: Although not as prominent as cognitive decline, motor dysfuncti on occurs in AD, particularly in the later stages of the disease. Objective : To determine whether early-stage AD is also characterized by motor impair ment. Methods: We examined very mildly (Clinical Dementia Rating [CDR] 0.5) and mildly (CDR 1) demented AD individuals in comparison with healthy elde rly control individuals (CDR 0) on a variety of nonmotor cognitive and psyc homotor measures and on four motor measures (gait velocity, finger tapping, reaction time, movement time). To minimize the possibility of extrapyramid al dysfunction contaminating the groups, only individuals who were clinical ly free of extrapyramidal signs were included in the study. Results: Mildly demented AD individuals were slowed on all motor measures except for finge r tapping. No evidence of motor dysfunction was found in the very mildly de mented AD group. As expected, both AD groups were impaired on the nonmotor cognitive and psychomotor tests. Conclusions: These results indicate that A D alone, in the absence of clinically confirmed extrapyramidal dysfunction, is associated with motor slowing in a stage-dependent manner. It remains t o be determined whether this motor slowing represents a general characteris tic of mild AD or indicates other neuropathology such as PD or the Lewy bod y variant of AD.