Trait Openness and serotonin 2A receptors in healthy volunteers: A positron emission tomography study

Recent research found lasting increases in personality trait Openness in healthy individuals and patients after administration of the serotonin 2A receptor (5-HT_2A R) agonist psilocybin. However, no studies have investigated whether 5-HT_2A R availability as imaged using positron emission tomography (PET) is associated with this trait. In 159 healthy individuals (53 females), the association between 5-HT_2A R binding in neocortex imaged with [¹⁸ F]altanserin or [¹¹ C]Cimbi-36 PET and personality trait Openness was investigated using linear regression models. In these models the influence of sex on the association was also investigated. Trait Openness was assessed with the NEO Personality Inventory-Revised. No significant associations between neocortical 5-HT_2A R binding and trait Openness were found for [¹⁸ F]altanserin (p = 0.5) or [¹¹ C]Cimbi-36 (p = 0.8). Pooling the data in a combined model did not substantially change our results (p = 0.4). No significant interactions with sex were found (p > 0.35). Our results indicate that differences in 5-HT_2A R availability are not related to variations in trait Openness in healthy individuals. Although stimulation of the 5-HT_2A R with compounds such as psilocybin may contribute to long-term changes in trait Openness, there is no evidence in favor of an association between 5-HT_2A R and trait Openness.