Pain Processing in Older Adults and Its Association with Prefrontal Characteristics

Abstract

Aging is known to affect nociceptive processing, e.g., the ability to inhibit pain. This study aims to investigate whether pain responses in older individuals are associated with prefrontal characteristics, namely (i) executive functioning performance and (ii) structural brain variations in the prefrontal cortex. Heat and pressure stimuli were applied to assess pressure pain sensitivity and endogenous pain inhibition in 46 healthy older individuals. Executive functioning performance was assessed in three domains (i.e., cognitive inhibition, shifting, and updating) and structural brain variations were assessed in both gray and white matter. Overall pain responses were significantly associated with the executive functioning domains cognitive inhibition and shifting. However, no specific type of pain response showed an especially strong association. Endogenous pain inhibition specifically showed a significant association with gray matter volume in the prefrontal cortex and with variations in white matter structure of tracts connecting the prefrontal cortex with the periaqueductal gray. Hierarchical regression analyses showed that these variations in the prefrontal cortex can explain variance in pain inhibition beyond what can be explained by executive functioning. This might indicate that known deficits in pain inhibition in older individuals are associated with structural variations in prefrontal areas.

Association between Self-Reported Pain, Cognition, and Neuropathology in Older Adults Admitted to an Outpatient Memory Clinic—A Cross-Sectional Study

“…Two studies that examined white matter integrity—a major correlate of EF [ 15 ]—in relation to self-reported pain in normal and pathological cognitive aging found that reduced white matter integrity (presumably reflecting worse EF) was related to higher self-reported, clinical pain levels [ 16 , 17 ]. These studies, therefore, corroborate experimental pain studies, in which worse EF was related to higher pain sensitivity [ 18 , 19 ]; these findings also support the results found in patients with VaD in whom higher pain reports and deficits in EF are concurrently present [ 8 ]. However, there are no studies that explored the roles of EF and white matter concurrently in self-reported, clinical pain in patients with cognitive impairment.…”

“…For instance, one study showed that cognitive inhibition explained 20% of the pain response variance in an experimental pain paradigm in pain-free older individuals. In fact, this study showed that a decreased cognitive inhibition and shifting ability were related to higher facial responses due to pressure pain [ 19 ]. This could reflect the involvement of EF in endogenous pain inhibition [ 48 ].…”

“…Based on previous studies, we expected an overall association between the performance on tests of EF and the self-reported occurrence (i.e., whether persons reported to be in pain) and level of pain. We explored whether this relationship was positive [ 11 ], or if the reversed relationship was present, in which worse EF is associated with a higher self-reported pain occurrence and higher self-reported pain levels [ 13 , 19 ]. We also hypothesized that an impairment in memory would be associated with lower self-reported occurrence of pain and lower self-reported pain levels as shown in another study [ 20 ].…”

Pain Processing in Cognitive Impairment and Its Association with Executive Function and Memory: Which Neurocognitive Factor Takes the Lead?

“…Furthermore, although the association between pain responses and executive functions in individuals with cognitive impairments (MCI and dementia) has appeared to be robust; there is some variability with regard to which subcategory of executive functioning plays the most important role. Abstract thinking, making plausibility judgments [10], cognitive inhibition, shifting [19], as well as cognitive flexibility (the present study) have been suggested as most important predictors for pain responses in MCI and dementia. Thus, a taxonomy is needed to differentiate between those executive functions that influence pain response and those not sharing this functional property.…”

“…Under this perspective, variations in neurocognitive functioning are always linked to variations in pain processing, even at nonpathological levels. There are several studies, which have tried to investigate this by using cross-sectional designs and correlated executive functioning and pain responses in cognitively healthy individuals [11,12,[16][17][18][19]. Using such designs, most studies (approximately 80%) did not find significant associations between the two functions [12].…”