The effects on comprehension of presenting medical prescription information in a pictorial format were compared to a verbal format in healthy old adults and in patients suffering from Alzheimer disease (AD). Participants received medical prescription instructions in one of two formats: with verbal instructions only, or with verbal instructions associated with pictorial representations. The results indicated that comprehension for prescription information of healthy old subjects and AD patients was facilitated by the combined presentation. Furthermore, the pictorial instructions appeared acting on the capacity to work out a specific medication schemata, that is to say on their real, operational, understanding. These results suggest that analogical pictorial format leads more directly to the medical prescriptions' situation model and alleviates the particularization deficiency of the therapeutic schemata, independently of global cognitive functioning, visual perception, space perception and visual semantic analysis in AD. The presentation of illustrations representing medical prescriptions would allow to decrease doubts and errors, which are frequent in normal aging and even more in Alzheimer's disease, and contribute to a better medical compliency.