Low-dose interferon-α is standard therapy for hepatitis C. Psychotic disorders have been described as a scarce complication of the treatment that resolves with its termination.

we present a patient with negative personal and familial psychiatric history who developed serious chronic psychotic disorder with persistent cognitive impairment on the level of dementia after seven month interferon-α therapy. Profound parkinsonian side-effects of neuroleptic treatment accompanied the disturbances.

Potentially severe brain consequences of long-term low-dose interferon-α therapy for hepatitis C in a susceptible individual may emerge. The underlying cause of the susceptibility remain obscure, however dopaminergic, opioid, serotoninergic and glutaminergic pathways as well as HPA axis hypersensitivity might be supposed. This biological vulnerability might interact with the cytokine's action on brain. Relatively frequent and in some cases serious neuropsychiatric adverse effects of interferon-α therapy indicate the necessity of regular psychiatric consultations during the treatment.