title: Irritability rather than depression during interferon treatment is linked to increased tryptophan catabolism.
abstract: OBJECTIVE
  Treatment with recombinant interferon is associated with high rates of psychiatric comorbidity. We investigated the relation between catabolism of the essential amino acid tryptophan, being rate-limiting of peripheral and cerebral serotonin formation, and psychiatric symptoms in patients undergoing combination treatment with interferon-alpha and ribavirin.
  
  
  METHODS
  Eighteen patients with viral hepatitis C who received interferon were included. A psychiatrist screened patients before and while on interferon-alpha treatment for 2 months, using a structured diagnostic interview. Fasting plasma tryptophan and platelet serotonin levels were measured at each visit.
  
  
  RESULTS
  At baseline no evident psychopathology was observed. After 2 months of interferon treatment, 10 patients experienced increased irritability. No other structural psychopathology was observed. Decreased plasma tryptophan level correlated with the presence of irritability (p = .047). Platelet serotonin levels were found to be decreased during treatment (p = .002).
  
  
  CONCLUSIONS
  Aggressive impulse dysregulation is highly prevalent in patients receiving interferon treatment. This is associated with decreased plasma tryptophan levels which may lead to attenuated peripheral and central serotonergic neurotransmission.
authors.affiliation: Department of Biological Psychiatry, University Hospital Groningen, Groningen, The Netherlands. s.r.russo@acggn.azg.nl
authors.forename: Sascha
authors.initials: S
authors.lastname: Russo
authors.forename: Ido P
authors.initials: IP
authors.lastname: Kema
authors.forename: Elizabeth B
authors.initials: EB
authors.lastname: Haagsma
authors.forename: Jim C
authors.initials: JC
authors.lastname: Boon
authors.forename: Pax H B
authors.initials: PH
authors.lastname: Willemse
authors.forename: Johan A
authors.initials: JA
authors.lastname: den Boer
authors.forename: Elisabeth G E
authors.initials: EG
authors.lastname: de Vries
authors.forename: Jakob
authors.initials: J
authors.lastname: Korf
mesh_terms: D000328:Adult; D000998:Antiviral Agents / Q000009:adverse effects* / Q000627:therapeutic use; D001792:Blood Platelets / Q000737:chemistry; D003866:Depressive Disorder / Q000139:chemically induced / Q000175:diagnosis / Q000453:epidemiology*; D004359:Drug Therapy, Combination; D005260:Female; D006526:Hepatitis C / Q000188:drug therapy* / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D015994:Incidence; D016898:Interferon-alpha / Q000009:adverse effects* / Q000627:therapeutic use; D007372:Interferons / Q000009:adverse effects* / Q000627:therapeutic use; D007508:Irritable Mood / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D011994:Recombinant Proteins / Q000009:adverse effects / Q000627:therapeutic use; D012254:Ribavirin / Q000627:therapeutic use; D012701:Serotonin / Q000032:analysis / Q000378:metabolism / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology; D014364:Tryptophan / Q000097:blood / Q000187:drug effects / Q000378:metabolism*
chemical_list: D000998:Antiviral Agents; D016898:Interferon-alpha; D011994:Recombinant Proteins; D012701:Serotonin; D012254:Ribavirin; D014364:Tryptophan; D007372:Interferons