title: [Opioids and cognition in patients with chronic pain: a systematic review].
abstract: OBJECTIVE
  The increasing use of opioids by patients suffering from chronic pain caused by different etiologies, and the possible effects of those substances on everyday activities, require careful evaluation of their effects. For this purpose, a systematic review was developed to assess the influence of opioids on the cognitive function in patients with chronic pain.
  
  
  METHODS
  Eleven databases were analyzed using the following descriptors: opioids, opiates, narcotics, cognitive impairment, cognitive dysfunction, cognitive disorders and pain. The inclusion criteria were: clinical trials or case reports which included patients with chronic pain in treatment with opioids, cognitive assessment by specific tests and publication in English, Spanish or Portuguese.
  
  
  RESULTS
  Sixteen surveys published between 1980 and 2004 met the criteria: six controlled trials, two randomized trials, and 10 studies of a lower scientific evidence level. All better quality controlled trials did not show cognitive impairment of patients under opioid therapy.
  
  
  CONCLUSIONS
  These results must be confirmed by additional randomized trials including a greater number of patients with chronic pain.
authors.affiliation: Saúde do Adulto, Escola de Enfermagem, Universidade de São Paulo. geanakurita@yahoo.com
authors.forename: Geana Paula
authors.initials: GP
authors.lastname: Kurita
authors.forename: Cibele Andrucioli de Mattos
authors.initials: CA
authors.lastname: Pimenta
authors.forename: Moacyr Roberto Cuce
authors.initials: MR
authors.lastname: Nobre
mesh_terms: D000701:Analgesics, Opioid / Q000009:adverse effects*; D002908:Chronic Disease; D002986:Clinical Trials as Topic; D003071:Cognition / Q000187:drug effects*; D003072:Cognition Disorders / Q000139:chemically induced*; D006801:Humans; D010146:Pain / Q000188:drug therapy*; D012107:Research Design / Q000592:standards; D016896:Treatment Outcome
chemical_list: D000701:Analgesics, Opioid