A laboratory study of patients with chronic allergic rhinitis: antihistamine effects on skilled performance

Twenty-four patients with chronic allergic rhinitis participated in a study of antihistamine effects on skilled performance. They were tested while experiencing symptoms and when they were free of symptoms. Within each symptom condition, they attended two sessions; each patient received a placebo capsule at one session and a 50 mg diphenhydramine capsule at the other. Subjects performed a battery of skilled performance tests, which included the Divided-Attention, Visual Backward Masking, Stimulus Response Conflict, and Vigilance tests. They rated the treatments and their performance. Affective states were assessed with the Profile of Mood States. Symptoms did not affect performance. Diphenhydramine impaired vigilance performance and measures of Divided Attention and Stimulus Response Conflict. Visual Backward Masking performance was not affected. The largest performance changes occurred when diphenhydramine was administered to subjects when they were free of symptoms.