Neuropsychological assessment of chronic non-malignant pain patients treated in a multidisciplinary pain centre.

The aim of the study was to investigate the influence of pain, sedation, pain medications and socio-demographics on cognitive functioning in chronic non-malignant pain patients. Chronic non-malignant pain patients (N=91) treated in a multidisciplinary pain centre were compared with age and sex matched healthy volunteers (N=64). Furthermore four subgroups of patients were examined: Group 1 (N=21) received no pain medications, group 2 (N=19) were in long-term oral opioid treatment, group 3 (N=18) were treated with antidepressants and/or anticonvulsants and group 4 (N=33) were treated with a combination of long-term oral opioids and antidepressants and/or anticonvulsants. Assessments comprised pain (PVAS) and sedation (SVAS), Continuous Reaction Time (CRT) testing for sustained attention, Finger Tapping Test (FTT) testing for psychomotor speed, Paced Auditory Serial Addition Task (PASAT) testing for information processing and working memory and Mini Mental State Examination (MMSE). CRT and FTT were impaired in the total patient sample. Treatment with opioids was associated with poorer performance of PASAT. High scores of PVAS and SVAS were associated with poor performance of PASAT and CRT, respectively. MMSE seems to be too insensitive for detecting the milder forms of cognitive impairment found in chronic non-malignant patients.