Abstract
Chronic non-cancer pain may impair numerous aspects of one's existence resulting in unemployment, disability, disruption of social roles, and impaired quality of life. In the last decade a rapidly increasing use of opioids for chronic non-cancer pain has been reported from several countries.
Concerns regarding opioid treatment of chronic non-cancer pain have primarily been based on the fear of addiction and diversion. However, other potentially important clinical issues such as dependency, tolerance development, abnormal pain sensitivity and dysfunction of the immune and reproductive systems may give rise to concerns.
One of the major worries of initiating long-term, sometimes life-long, opioid treatment in patients with chronic non-cancer pain is the potential introduction of cognitive dysfunction, manifested as e.g. impaired capacity for concentration, deficits in information processing and memory, slower psychomotor speed and reaction time. Empirical research exploring the opioid-cognition relationship exists across several patient groups including cancer pain, chronic non-malignant pain conditions, and healthy controls.
Outcomes measures include both global cognition and specific neuropsychological domains such as memory, processing speed, executive functioning, or driving ability. However, the opioid-cognition literature seems thus far equivocal: despite subjective reports of mental dullness and sedation, only a small number of studies have observed mild cognitive effects as a result of opioid therapy.
Many studies have not yet adequately demonstrated significant cognitive effects of opioid use, and a small body of research has actually demonstrated improvements in cognitive functioning. Previous reviews of the opioid-cognition literature highlighted such disagreement across studies.
The aim of this article is to review the neuropsychological sequelae of chronic non-cancer pain and opioid therapy, to clarify roles and benefits of neuropsychological assessment in a chronic pain population, and to provide recommendations for clinical practice and future research.