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.