[Cerebral dysfunction after prolonged use of opioids].

Cerebral dysfunction due to long-term treatment with opioids is a problem of increasing relevance because of the rapidly growing use of opioids. A review of psychomotor and cognitive test methods is given, including their application in patients on long-term opioid treatment. The findings of the most valid studies on cancer patients in long-term treatment with opioids are an increase in continuous reaction time and subjective sedation score regardless of the routes of administration. Studies of drug addicts in long-term treatment with opioids seem to reflect a lowering of the general level of activity. According to recent studies, patients with chronic non-malignant pain conditions are responsible for the major part of the total opioid consumption. So far, no studies of cerebral dysfunction have been performed on this group of patients. Further research should concentrate on the use of few valid psychomotor and cognitive tests and should include patients with chronic non-malignant pain conditions.