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Abstract:
GOALS: Alzheimer's Disease (AD) patients typically display a
disturbance in their ability to draw geometric figures. We compared
the process by which they and normal controls (NC) made simple
drawings to characterize these disturbances better. METHOD: 30 AD
and 30 NC subjects copied freehand simple figures presented to them
on stimulus cards onto a piece of paper placed on a digitizer
tablet sampling position at 100 Hz. From the resulting x/y
trajectories we extracted measures of drawing structure (e.g.,
stroke order and direction), speed, precision, and fluency.
RESULTS: AD subjects drew the figures more slowly with less
fluency, precision, and stability across repetitions than the NC
group. ADs also often structured the drawing of a figure
differently. For example, they did not adhere to customary choices
for stroke order and direction. In addition, ADs were more likely
to separate lines, which NCs produce continuously into multiple
strokes. CONCLUSIONS: The AD subjects exhibit general deficits such
as being slower and less fluent than the NC subjects. The drawing
behavior of the ADs suggests that their planning behavior is
different from the NC group; in particular, AD subjects appear to
parse figures differently from NCs. NIH Grant 1Ro1 AG13967
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