Line orientation judgment in normal elderly and subjects with dementia of Alzheimer's type.

Ninety-five normal controls divided into three subgroups (55-64 yrs, 65-74 yrs, and 75-84 yrs) and 11 subjects with early dementia of Alzheimer's type (DAT) were given a line orientation judgment task (Benton, Varney, & Hamsher, 1978). No difference appeared between the three control subgroups in global score but the difference between controls and DAT subjects was significant. However, some DAT subjects had a global score overlapping the scores of controls. Error types were also analyzed. Results of this analysis showed that some errors appeared in all subjects, normal and DAT, while others were specific to DAT subjects. It was speculated that these error types were a manifestation of a deeper visuospatial deficit, revealing a major problem of the DAT in spatial organization. Thus, this study suggests that an analysis of the error types observed in the line orientation judgment task may be helpful in differentiating normal elderly from early DAT.