Cognitive impairment in neurofibromatosis type I (NF1) has only recently attracted interest. In addition to previous studies in children, our own investigation of 20 patients confirms the slightly lowered psychometric test scores also for adults with NF1. Molecular manipulation of the neurofibromin gene leads to learning disorders in the mouse model ("cognitive neurogenetics"). It is not just faulty brain development that underlies these findings: neurofibromin plays a role in signal transduction cascades that are active during learning and memory throughout the life span. Thus, it appears possible to cure the cognitive defects at least in the mouse ("cognitive enhancement"). In man, an early diagnosis of NF1 is presently essential in order to provide specific remedial education for children affected by the learning disorder of neurofibromatosis type I.