Background: There is a growing number of patients worldwide being treated with longterm opioids for chronic non-cancer pain, although there is limited evidence for their
effectiveness in improving pain and function. Opioid-use related adverse effects, especially
in cognitive functioning in these patients, are rarely evaluated.
Objectives: The present study investigated the cognitive functions of patients with chronic
back pain who underwent long-term opioid treatment in comparison with those patients
without opioid usage and healthy controls.
Study Design: A prospective, nonrandomized, cross-sectional study.
Setting: Multidisciplinary pain management clinic, specialty referral center, University
Hospital in Germany.
Methods: In a prospective cross-sectional design, 37 patients with chronic back pain who
underwent long-term opioid therapy (OP) were compared with 33 patients with chronic
back pain without opioid therapy (NO) and 25 healthy controls (HC). Assessment of primary
outcome included cognitive function such as information processing speed, choice reaction
time, pattern recognition memory, and executive function. Other data included pain, back
function, depression and anxiety, use of medication, and education status. The relationship
between cognitive functions and anxiety/depression was analysed.
Results: Both patient groups needed significantly longer time in information processing
when compared to HC (Group 1: 41.87 ± 20.47 Group 2: 38.29 ± 19.99 Group 3: 30.25 ±
14.19). Additionally, OP patients had significantly reduced spatial memory capacity, flexibility
for concept change, and impaired performance in working memory assessment compared
to NO patients and HC. The impaired cognitive outcomes were significantly associated with
pain intensity, depression scores, and medication use.
Limitations: Limitations include small number of patients with heterogeneous opioid
therapy and the nonrandomized observational nature of the study.
Conclusions: Our findings give a differential view into the cognitive changes from
chronic back pain with and without long-term opioids treatment. Chronic back pain itself
impairs some distinct cognitive functions. Long-term opioid therapy adds further cognitive
impairment.
Key words: Long-term opioid therapy, chronic back pain, cognitive dysfunction