Dj. Libon et al., FURTHER ANALYSES OF CLOCK DRAWINGS AMONG DEMENTED AND NONDEMENTED OLDER SUBJECTS, Archives of clinical neuropsychology, 11(3), 1996, pp. 193-205
In a previous article we described a 10-point scoring system (i.e., sc
ale I) to grade clock drawings to command and copy with hands set for
''ten after 11'' among demented patients. Alzheimer's subjects (AD) im
proved from the command to copy conditions, whereas subjects with isch
aemic vascular dementia (IVD) did not. To investigate the underlying c
ognitive deficits responsible for this profile, an additional scale wa
s developed (scale 2) that tallied errors in graphomotor functioning,
hand/number placement, and executive control. On an independent sample
of subjects, AD subjects, again, made significant improvement on scal
e I from the command to copy condition, whereas no such improvement oc
curred among the IVD subjects. On scale 2, IVD subjects made more grap
homotor errors in the command condition, and more executive control an
d more total errors in the copy conditions than AD subjects. A number
of positive correlations were noted between tests of language and memo
ry on scale 1. By contrast, scares on tests of executive control decli
ned as scale 2 errors increased. In addition, a principal component an
alysis indicated that scale 2 test performance loaded on a factor with
other tests related to executive control. These results suggest that
impairment in frontal systems functioning may explain why IVD subjects
do not improve from the command to copy conditions on scale 1. Such a
pattern of performance in clock drawing may also be helpful in making
a differential diagnosis between AD and IVD.