Persistent neurotoxicity of systemically administered interferon-alpha.

Fourteen cancer patients had evidence of persistent neurotoxicity of interferon-alpha therapy long after their treatment was discontinued. Although most of the cognitive symptoms were mild to moderate in severity, they were incapacitating to these individuals in their usual work. The neuropsychological test abnormalities were not attributable to subsequent therapy, disease status, or other medical problems. The pattern of deficits was consistent with frontal-subcortical dysfunction. Of the four patients who had follow-up assessment, two had improved and two had deteriorated. These findings suggest that in some cases interferon neurotoxicity is not reversible.