Interactive effects of age and brain disease on reaction time.

Simple visual and auditory reaction time (RT) was studied in younger (16 to 44 years old) and older (46 to 63 years old) control and brain-diseased patients. Differences in RT related to age were larger for brain-diseased than control patients. Differences in RT related to diagnostic category were larger for older than younger patients. Analysis indicated an interactive effect of age and brain disease on RT supporting the suggestion that acquired brain disease leads to a more pronounced retardation in RT in older patients.