Postural set for balance control is normal in Alzheimer's but not in XXXX .

@entity1 @entity303 @entity191 @entity74 @entity195 @entity21 @entity2798
BACKGROUND: It has been suggested that @entity1 with @entity303 of the Alzheimer type have @entity21 , and thus, may have similar sensorimotor problems as @entity1 with @entity21 from @entity191 . Whether the similarity extends to balance control is unknown. One distinguishing feature of @entity74 in @entity191 is difficulty with changing postural set in terms of adapting the amplitude of leg muscle activity as a function of support condition. We, therefore, tested whether @entity1 with @entity195 without @entity21 would show a similar problem in changing postural set as @entity1 with @entity191 . METHODS: The ability to quickly change postural set was measured by comparing leg muscle activity under two conditions of support (free stance, versus grasping a frame, or sitting) during backward surface translations, during toes up surface rotations, and during @entity2798 to toes. Results were compared among 12 healthy adults, 8 nondemented @entity191 @entity1 on their usual dose of medication, and 11 Alzheimer @entity1 without @entity21 . RESULTS: Subjects with Alzheimer's, but not @entity191 performed similarly to the healthy control subjects. They changed postural set immediately, by suppressing leg muscle activity to low levels when supported. Parkinson subjects did not change postural set immediately. They did not suppress the tibialis anterior in @entity2798 to toes when holding, nor the soleus in perturbed sitting as much as the healthy control and Alzheimer subjects in the first trial. Instead, the Parkinson subjects changed set more slowly, over repeated and consecutive trials in both protocols. The onset latencies of soleus responses to backward surface translations and perturbed sitting, as well as tibialis anterior responses to toes up rotations, were the same for all three groups. CONCLUSION: Alzheimer @entity1 without @entity21 , unlike nondemented @entity191 @entity1 , have no difficulty in quickly changing postural set in response to altered support conditions. Our results, therefore, do not support the hypothesis that @entity191 and uncomplicated @entity195 share common postural set problems that may contribute to disordered balance control.
