The mydriatic effect of topically administered tropicamide was investigated as a possible diagnostic indicator for Alzheimer's disease. Although an initial series seemed to show a correlation between hypersensitivity to tropicamide and intellectual impairment, subsequent testing showed a greater inter- and intra-individual variation than that between the normal group and the group of patients with intellectual impairment. This procedure seems, therefore, to lack sufficient specificity to be useful for such a diagnostic purpose. Copyright © 1996 Elsevier Science Ltd