Few studies have investigated associations between alexithymia and physiological mechanisms in psychosomatic diseases
. We examined associations between alexithymia and 1) perception and brain processing of visceral stimulation and 2) the endocrine responses to corticotrophin-releasing hormone
(CRH) in healthy individuals and patients with irritable bowel syndrome (IBS).
The study included 29 patients with IBS and 35 age- and sex-matched healthy controls (HCs). Alexithymia was measured using the 20-item Toronto Alexithymia Scale
(TAS-20). Brain responses to rectal distention and its anticipation were measured by functional magnetic resonance imaging and analyzed at a voxel-level threshold of puncorrected
< .001 combined with a cluster-level threshold of pFWE-corrected
< .05. On a different day, plasma adrenocorticotropic hormone and cortisol responses after intravenous CRH administration were measured.
TAS-20 scores did not differ significantly between patients with IBS and HCs (p
= .18). TAS-20 scores correlated positively with the individual rectal discomfort thresholds (βrobust
= 0.49, p
= .03) and negatively with the rating of fear before rectal distention (βrobust
= −1.63, p
= .04) in patients with IBS but not in HCs. Brain responses to rectal distention in the right insula and other brain regions were positively associated with TAS-20 scores to a greater extent in patients with IBS than in HCs. Individuals with higher TAS-20 scores (both patients with IBS and HCs) demonstrated stronger adrenocorticotropic hormone responses to CRH administration (F
(4,224) = 3.54, p
Higher alexithymia scores are associated with stronger physiological responses, but lower anticipatory fear ratings and higher discomfort thresholds, particularly in patients with IBS.