The Relationship Between Pain and Mental Flexibility in Older Adult Pain Clinic Patients

OBJECTIVE: Persistent pain and cognitive impairment are each common in older adults. Mental flexibility, memory, and information-processing speed may be particularly vulnerable in the aging brain. We investigated the effects of persistent pain on these cognitive domains among community-dwelling, nondemented older adults. SETTING: Older Adult Pain Management Program. DESIGN: A total of 56 new patients (mean age 76.1 years) were recruited to describe 1) rates of persistent pain conditions and pain intensity; 2) cognition (mental flexibility, short-term memory, and psychomotor speed); 3) severity of depression; and 4) sleep quality. All patients had nonmalignant pain for at least 3 months. Pain intensity was measured with the McGill Pain Questionnaire and depression severity with the 17-item Hamilton Rating Scale for Depression. Cognition was assessed with 1) Mini-Mental State Exam; 2) Number-Letter-Switching and Motor Speed subtests of the Delis-Kaplan Executive Function System Trail Making Test; 3) Digit Symbol Subtest (DSST) of the Wechsler Adult Intelligence Scales-III; and 4) free and paired recall of the DSST digit-symbol pairs. Multiple linear regression modeled whether these variables predicted poorer cognitive outcomes, after adjusting for the effects of opioids, sleep impairment, depression, medical comorbidity, and years of education. RESULTS: In univariate analysis, pain severity was associated with a greater impairment on number-letter switching (r = -0.42, P = 0.002). This association remained after adjusting for the effects of depression, sleep, medical comorbidity, opioid use, and years of education (t = -1.97, P = 0.056). CONCLUSIONS: In community dwelling older adults, neither pain nor mood was associated with measures of short-term memory or information-processing speed. However, pain severity was associated with decreased performance on a test of number-letter switching, indicating a relationship between pain and mental flexibility.