Unilateral spatial neglect in AD: significance of line bisection performance

Unilateral spatial neglect has been rarely reported in patients with AD, although they often have right and left asymmetry of temporoparietal dysfunction.

To investigate if patients with AD would show unilateral spatial neglect in the line bisection test, and to reveal the relationship between their neglect and the area of cerebral dysfunction.

Thirty-two patients with mild to moderate AD and 32 age-matched healthy control subjects underwent an extensive line bisection test. SPECT was also obtained for the patients.

Rightward bisection errors exceeded the normal range in 25% of patients with AD. They exhibited greater rightward errors for the longer lines in the left hemispace than in the right hemispace, and with the right hand than with the left hand; this corresponds to the characteristics of neglect seen after right hemisphere lesions. All patients who bisected 200 mm lines with errors over 10 mm showed disproportionate lowering of performance IQ and asymmetric right hemisphere hypoperfusion, especially in the temporoparietal region. Seventy-five percent of the patients performed normally in the center presentation but erred slightly toward the body midline in the right and left hemispaces.

Left unilateral spatial neglect in mild to moderate AD may be rather common if tested with the line bisection test. Rightward errors over 10 mm suggest right temporoparietal dysfunction. In AD, three or more bisections of 200 mm lines in the center presentation are recommended for detection of neglect. Patients with AD but without neglect may have difficulty in shifting attention into the peripheral sector of the egocentric space.