Pain expression in mild cognitive impairment: Its relation to frontal lobe involvement in non-verbal pain expression.

Background/Purpose: Pain is prevalent and often undertreated in elderly individuals suffering from cognitive impairments. Interestingly, such individuals may actually show an increase in facial expressions of pain. The reasons for this are unclear, but may possibly relate to disinhibition due to frontal lobe impairment. It was hypothesized that elderly individuals who suffer from mild cognitive impairments (MCI) would display higher levels of pain expression than normal controls, particularly if they have deficits in frontal lobe functioning. Methods: A sample of elderly individuals were recruited from the community and labeled as MCI' if they scored <26 on the Montreal Cognitive Assessment Task (MoCA). A comparison sample (control group) consisted of individuals scoring '~\u202226 on this test. Facial expressions were videotaped and then rated and scored for pain intensity at the time of an influenza vaccination and participants were subsequently questioned regarding their subjective experience of the painful stimulus. They also underwent neuropsychological testing of frontal lobe functions (in particular, executive functioning) including the Wisconsin Card Sorting Test (WCST), Stroop Test, and verbal fluency testing. Social inhibition was assessed through a self-disclosure interview. Results: There were 58 participants ranging in age from 56 to 92 yrs (M=69.7 SD=8.3). Of this group, 34 met criteria for MCI based on MoCA scores (i.e., MCI group) while 24 did not (control group). There were no significant differences between the two groups with respect to facial expressions of pain, subjective reports of pain, nor social inhibition scores. While executive functioning was relatively impaired in the MCI group, the degree of impairment did not correlate with facial expressions of pain not with social inhibition scores. Conclusion: Contrary to expectations, no significant differences were found between participants identified as having MCI and normal controls in their facial expressions of pain post-im