Treatment for pain and related conditions has been identified as the most common reason for Emergency Department (ED) visits. Concerns exist regarding the effects of opioid pain medications on cognition and patient ability to consent for procedures, hospital admission, or to refuse recommended medical interventions. This study was undertaken to identify cognitive skills before and after opioid pain medication in the ED setting.

This was a prospective study comparing performance on the Mini-Mental Status Examination (MMSE) and Montreal Cognitive Assessment (MoCA) before and after administration of opioid pain medications. Eligible participants included ED patients with pain, who received opioid treatment. Participants were randomized to receive either the MMSE before pain medication and the MoCA after medication, or the reverse. MoCA scores were converted to MMSE equivalent scores for comparison.

Among 65 participants, the median age was 36 and median triage pain score was 8. 35% of patients were considered cognitively impaired based on their MMSE score prior to any opioid medication (MMSE<27). There was a median decrease in pain scores of 1 point following pain medication, p-value<0.001. There was a median decrease in MMSE scores of 1 point following pain medication, p-value=0.003. The range of change in scores (post minus pre) on the MMSE-equivalent was −7 to 3. 35 patients (56%) had a decrease in scores, 6 (10%) had no change, and 21 (34%) had an increase. After medication, 31 (48%) were abnormal (MMSE score<27). No differences in MMSE scores were identified by gender, ethnicity, mode of arrival, insurance, age, triage pain scores, opioid agent given, or ED diagnosis.

There is an association between opioid pain medication and decrease in cognitive performance on the MMSE. Because of the wide range of cognitive performance following opioid pain medication, assessment of individual patients' cognitive function is indicated.