Decreased parasympathetic activity in patients with functional dyspepsia

Functional dyspepsia (FD) can be described as the presence of symptoms such as bothersome postprandial fullness, early satiation, epigastric pain, and burning without any evidence of structural disease. The aim of this study was to evaluate the autonomic nervous system using heart rate variability (HRV) in patients with postprandial distress syndrome and epigastric pain syndrome.

The study population included 64 consecutive patients with a diagnosis of FD and 62 age-matched and sex-matched healthy control individuals with no clinical evidence of gastrointestinal, systemic, or cardiovascular diseases. All patients underwent upper gastrointestinal endoscopy and 24 h Holter monitoring.

There were 30 patients with postprandial distress syndrome and 34 with epigastric pain syndrome. Twenty-four hour square root of the mean squared differences of the successive normal to normal intervals (RMSSD) (30.5 ± 12.4, 35.8 ± 13.9; P=0.047), 24 h proportion derived by dividing the number of interval differences of successive normal to normal intervals greater than 50 ms (PNN50) (9.8 ± 3.9, 14.1 ± 7.3; P=0.017), daytime PNN50 (6.8 ± 1.6, 18.4 ± 13.8; P<0.001), night SD of the normal to normal intervals (SDNN) (111.4 ± 39.9, 133.4 ± 29.8; P=0.001), and night RMSSD (31.7 ± 12.4, 38.2 ± 17.5; P=0.019) were significantly lower in patients with FD than controls. Other HRV parameters were not significantly different between the two groups. Changes in these parameters showed a decreased parasympathetic tone and discordance in sympathovagal activity in FD.

Our study showed decreased parasympathetic activity in the patients with FD. Further studies are required to evaluate the significance of HRV parameters and to clarify the mechanism of decreased parasympathetic activity in patients with FD.