Objective The Autonomous Nervous System (ANS) is an important route of brain-gut communication.
Aberrant ANS functioning, reflected in abnormalities in Heart Rate Variability (HRV)
has been described in irritable bowel syndrome (IBS). Gut-directed hypnotherapy (GHT)
leads to symptom reductions in IBS and is supposed to increase parasympathetic regulation.
To date, the role of therapeutic modulation of the ANS through GHT has been rarely
examined. Aim of this pilot study was to assess the impact of GHT on ANS functioning
as reflected in HRV.
Methods Nine patients (8 female, 1 male, Mean age 46,8 years) with IBS (Rome IV criteria)
were assessed via 24h-electrocardiogram before and after 10 sessions GHT, administered
in groups. Time and Frequency measures of HRV were extracted as indicators of ANS
regulation. Questionnaires were utilized to assess IBS symptoms (IBS-SSS) and psychological
distress (HADS-D).
Results No significant change in HRV measures was detectable after GHT (all p’s>.52). Trends
of lowered standard deviation of the normal-to-normal interval (SDNN) (157,2 [125;
170,9] vs. 145,1 [108,4; 160,3]) and high frequency power (HF) (2,83 [2,61; 2,84]
vs. 2,56 [2,23; 2,70]) indicated reduced HRV and vagal activity after hypnosis. Courses
of HRV indices were either increasing (4 patients) or decreasing sharply (5 patients)
with no overlap. IBS symptoms (254 ± 78,7 vs. 190,0 ± 85,7, p = .026) and psychological
distress (Anxiety 9,50 ± 2,07 vs. 6,36 ± 3,25, Depression 7,63 ± 3,07 vs. 5,29 ± 2,50,
p = .038 respectively) decreased significantly in the whole sample.
Conclusion While HRV remained relatively stable overall, the courses of HRV pre-post therapy
were either increasing or decreasing, with two distinct clusters of patients. Symptom
improvements were observed in the majority of patients, possibly pointing a more psychological
impact of GHT. Better powered studies are warranted to examine the effects of hypnosis
on HRV in IBS.
