Thermal Psychophysics and Associated Brain Activation Patterns along a Continuum of Healthy Aging

• Type of Material: Article
• Authors: Paul Beach, Emory University; Ronald L. Cowan, Vanderbilt University; Mary S. Dietrich, Vanderbilt University; Stephen P. Bruehl, Vanderbilt University; Sebastian W. Atalla, Ohio State University; Todd B. Monroe, Ohio State University
• Language: English
• Date: 2020-01-01
• Publisher: American Academy of Pain Medicine
• Publication Version: Final Published Version
• Copyright Statement: © 2019 American Academy of Pain Medicine.
• License: Creative Commons Attribution-NonCommercial 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1093/PM/PNZ281
• Title of Journal or Parent Work: Pain Medicine (United States)
• Volume: 21
• Issue: 9
• Start Page: 1779
• End Page: 1792
• Grant/Funding Information: The project described was supported by the National Center for Research Resources, Grant UL1 RR024975-01, and is now at the National Center for Advancing Translational Sciences, Grant 2 UL1 TR000445-06. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
• Keywords: Pain Threshold; Magnetic Resonance Imaging; Cross-Sectional Studies; Humans; Geriatric; Perception; Psychophysics; Aged; Magnetic Resonance Imaging (MRI); Healthy Aging; Pain Perception; Brain; Older Adults
• Research Categories: Health Sciences, Human Development; Health Sciences, Radiology; Biology, Neuroscience

Abstract

Objective. To examine psychophysical and brain activation patterns to innocuous and painful thermal stimulation along a continuum of healthy older adults. Design. Single center, cross-sectional, within-subjects design. Methods. Thermal perceptual psychophysics (warmth, mild, and moderate pain) were tested in 37 healthy older adults (65–97 years, median ¼ 73 years). Percept thresholds (oC) and unpleasantness ratings (0–20 scale) were obtained and then applied during functional magnetic resonance imaging scanning. General linear modeling assessed effects of age on psychophysical results. Multiple linear regressions were used to test the main and interaction effects of brain activation against age and psychophysical reports. Specifically, differential age effects were examined by comparing percent-signal change slopes between those above/below age 73 (a median split). Results. Advancing age was associated with greater thresholds for thermal perception (z ¼ 2.09, P ¼ 0.037), which was driven by age and warmth detection correlation (r ¼ 0.33, P ¼ 0.048). Greater warmth detection thresholds were associated with reduced hippocampal activation in “older” vs “younger” individuals (>/<73 years; beta < 0.40, P < 0.01). Advancing age, in general, was correlated with greater activation of the middle cingulate gyrus (beta > 0.44, P < 0.01) during mild pain. Differential age effects were found for prefrontal activation during moderate pain. In “older” individuals, higher moderate pain thresholds and greater degrees of moderate pain unpleasantness correlated with lesser prefrontal activation (anterolateral prefrontal cortex and middle–frontal operculum; beta < –0.39, P < 0.009); the opposite pattern was found in “younger” individuals. Conclusions. Advancing age may lead to altered thermal sensation and (in some circumstances) altered pain perception secondary to age-related changes in attention/novelty detection and cognitive functions.