• Michiko Kano, Tomohiko Muratsubaki, Mao Yagihashi, Joe Morishita, Shunji Mugikura, Patrick Dupont, Kei Takase, Motoyori Kanazawa, Lukas Van Oudenhove, and Shin Fukudo.
• From the Frontier Research Institute for Interdisciplinary Sciences (Kano) and Behavioral Medicine, Graduate School of Medicine (Kano, Muratsubaki, Yagihashi, Morishita, Kanazawa, Fukudo), Tohoku University; Diagnostic Radiology (Mugikura, Takase), Tohoku University Hospital, Sendai, Japan; Laboratories for Cognitive Neurology (Dupont) and Brain-Gut Axis Studies, Translational Research Center for Gastrointestinal Disorders (Van Oudenhove), KU Leuven, Leuven, Belgium.
• Psychosom Med. 2020 Jan 1; 82 (1): 29-38.

ObjectiveFew 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).MethodsThe 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.ResultsTAS-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 = .008).ConclusionHigher alexithymia scores are associated with stronger physiological responses, but lower anticipatory fear ratings and higher discomfort thresholds, particularly in patients with IBS.

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