Psychological factors, such as anxiety, depression, and pain catastrophizing, may affect how healthy individuals experience experimental pain. However, current literature puts forth contradictory results, possibly due to differing study methodologies, such as the type of psychophysical measure or survey. To better understand such results, this paper analyzed the relationships between psychological factors and experimental pain outcomes across eight different studies (total n= 595) conducted in different populations of healthy adult and adolescent participants. Analyses were conducted with and without controlling for sex, age, and race. Each study was analyzed separately and as part of an aggregate analysis. Even without correction for multiple comparisons, only a few significant relationships were found for the individual studies. Controlling for demographic factors had minimal effect on the results. Importantly, even the few statistically significant models showed relatively small effect sizes; psychological factors explained no more than 20% of the variability in experimental pain sensitivity of healthy individuals. The aggregate analyses revealed relationships between anxiety and PPT / cold pain ratings and between pain catastrophizing and PPT. Sample size calculations based on the aggregate analyses indicated that several hundred participants would be required to correctly detect relationships between these psychological factors and pain measures. These overall negative findings suggest that anxiety, depression, and pain catastrophizing in healthy individuals may not be meaningfully related to experimental pain outcomes. Furthermore, positive findings in the literature may be subject to small group effects and publication bias towards positive findings.
Heritability of pain catastrophizing and associations with experimental pain outcomes
