Pain and cognitive functioning in community-dwelling older adults

Summary Introduction Chronic pain is frequently reported in older adults and the prevalence will only increase with the rising number of older adults as a result of the baby-boom generation. The aim of our studies was to clarify the association between pain and several domains of cognitive functioning in older adults, which may shed light on potentially modifiable risk factors for cognitive impairment in aging. Pain and cognition cross-sectionally We found that pain severity was associated with impaired memory, executive functioning, and general cognitive performance and pain interference (with daily activities) with impaired attention, memory, executive functioning and general cognitive performance, after adjustments for age, gender, race and education. However, many of these associations were not statistically significant anymore after additional adjustments for chronic conditions and psychiatric medications. The association between pain interference and memory and general cognitive performance in older adults persisted, even after adjusting for demographics, chronic conditions, behaviors, and psychiatric medication. We also found that the observed relationships between pain and cognitive performance were partly explained by the effect of pain on attentional resources. Therefore we focused on the association between pain and attention in the next chapters. First we found that the Test of Everyday Attention (TEA), which was only validated to measure attention in adults 18-80 years old, is also a valuable tool to measure attention in the very old (chapter 3). However, the Visual Elevator Test, which measures the domain of attentional switching, was the most challenging test for these older participants. In chapter 4 we showed that higher pain severity was associated with poorer scores in measures of selective and sustained attention. Pain interference scores were also significantly inversely associated with selective attention. These cross-sectional results in the previous chapters suggest that pain demands attention and takes precedence over other attention-demanding cognitive tasks. Pain and cognition longitudinally Longitudinal studies about the associations between pain and multiple domains of cognition are mostly lacking. In chapter 5, we found that the presence of severe pain at baseline increases the risk of developing incident memory impairment in older adults in our study. We found no associations between pain and incident attention or executive functioning impairments. Potential mechanism In chapter 6, our aim was to study if CPR plays a mediating role in the association between severe pain and cognition. The association we found between severe pain and impaired cognition was not significant anymore after adjustment for several possible confounders and therefore we were not able to establish a possible mediating role of CRP. Pain and MCR Finally, in chapter 7, we analyzed the cross-sectional and longitudinal associations between pain and the Motoric Cognitive Risk Syndrome (MCR). We found that older adults with severe pain had an increased risk of prevalent MCR, compared to those without pain, after adjusting for demographic, peripheral, central or biological risk factors. Also, in an independent cohort, we showed that older adults with severe pain had a more than five times increased risk of developing incident MCR, compared to those without pain. Discussion To conclude, the association between pain and cognition is complex. Cross-sectionally, pain is associated with impaired memory, impaired specific domains of attention, and impaired general cognitive performance, after adjustments for multiple confounders. Longitudinally, severe pain is associated with incident memory impairment and incident MCR. Health care providers evaluating patients with pain should be aware of the possible changes in cognition and might refer patients for further neuropsychological assessments in case of uncertainty about cognitive performance. Future research should evaluate whether cognitive impairment in pain patients is reversible and whether treatment of pain leads to improved cognitive functioning.