Visuospatial deficits in Parkinson's disease assessed by judgment of line orientation test: error analyses and practice effects.

The Benton's Judgment of Line Orientation (JLO) is one of the tests most frequently used to assess visuospatial function. The aim of the present study was to analyze qualitative errors in Parkinson's disease (PD) following the method described by Ska, Poissant, and Joanette (1990) and to determine possible practice effects of this test. The JLO was administered to 76 idiopathic PD patients and 76 matched normal controls. The analyses of errors showed several qualitative differences between groups. Parkinson's patients made a greater proportion of complex intraquadrant errors and horizontal line errors, while they showed fewer simple intraquadrant errors than controls. The JLO test was also administered twice in an interval of 20 min in a subsample of 25 PD patients and 25 normal controls. The results did not show significant differences between the two administrations, indicating that the test is free of practice effects. In conclusion, these data provide further evidence for the existence of visuospatial deficits in PD. Moreover, the JLO has proved to be an appropriate test for the assessment of the visuospatial function in patients who require a neuropsychological follow up.