A validity study of the Working Group's Orientation Test for individuals with moderate to severe intellectual disability

Background Decline in orientation skill has been reported as an early indicator of Dementia of Alzheimer's Type (DAT). Orientation subtest of the Working Group's Test Battery was examined whether this test is useful to identify DAT patients among adults with moderate to severe ID. Methods Sixteen DAT patients and 35 non-demented normal controls with moderate to severe ID were followed for a year using Orientation Test. The scores on the baseline evaluation and the longitudinal changes over a 1-year period among the DAT patients and the normal controls were compared. The effects of age and etiologies of ID on the performance of Orientation were also examined. Results The DAT group's score was significantly poorer than that of the normal control group on the baseline evaluation. The score changes over the 1-year period were not significantly different between the groups. However, there was a considerable overlap between the score distributions of the two groups. The effects of age and etiologies of ID on the performance of Orientation were not significant. Conclusions Screening DAT patients based only on the score of the Orientation Test of the Working Group's Test Battery may produce a large number of diagnostic errors.