A number of data support the involvement of immunological mechanisms in the etiology of psychiatric disorders. The nervous and immune systems are physiologically integrated and influence each other's functioning.

    Clinical studies have reported a larger number of psychiatric symptoms consecutive to immunomodulating interferon therapy. The most frequent are depression, suicidal behavior, manic syndrome, anxiety disorders, psychotic disorders and delirium associated with an array of unspecific psychiatric symptoms: fatigue, irritability, psycho-motor retardation, decreased libido, insomnia, concentration difficulties and attention deficit. Another undesired consequence of interferon therapy is the worsening of a preexistent psychiatric disorder. Thus, a history of psychiatric disorder is currently one of the contraindications of interferon therapy. 

    Psychiatric adverse events may occur either shortly after the initiation of therapy, or as a result of ongoing treatment, but most adverse events occur after 3 weeks of treatment. 

    Although there are relatively few studies on statistically significant patient samples, current data underline the importance of managing these effects and also the most indicated treatment strategies. Therefore, an improved psychiatric management of these adverse effects may change the gastroenterologist's decision to exclude from treatment high – risk patient categories such as those with mood disorders, alcohol or drug abuse, or other addiction.


interferon, depression, neurotoxicity