Interferon-induced organic mental disorders associated with unsuspected pre-existing neurologic abnormalities.

Eleven patients ranging in age from 52 to 80 years, undergoing treatment for cancer with various preparations of interferon received neurobehavioral evaluations after experiencing unexpectedly severe organic mental disorders. The reactions ranged from delirium to extrapyramidal symptoms, mania, and neurasthenia with catatonic episodes. Computed tomographic (CT) scans of the brain disclosed unsuspected pre-existing neurologic abnormalities in all patients, including cerebral atrophy (6/11), brain metastases (4/11), and evidence of head injury incurred 40 years earlier (1/11). These findings suggest that cancer patients with pre-existing neurologic dysfunctions are at increased risk for severe interferon neurotoxicity.