Heart rate variability is related to pain severity and predominant bowel pattern in women with irritable bowel syndrome.

This study examined heart rate variability (HRV) in women with irritable bowel syndrome (IBS) to determine its association with gut pain and predominant bowel pattern. Women with IBS (constipation predominant n = 45, diarrhoea predominant n = 64, alternating n = 56) and healthy controls (n = 50) were recruited from the community. Severity of gut pain was measured retrospectively. The HRV (24 h) was summarized as high-frequency (HF) power and the ratio of low-frequency (LF) power to HF power. Among those women with IBS who have severe gut pain, the 15 constipation-predominant women had lower (P = 0.01) HF power and higher (P = 0.003) LF/HF ratio (geometric means 70 and 7.5, respectively) than the 21 women with diarrhoea-predominant IBS (286 and 3.1) and controls (224 and 3.9). In contrast, among women without severe pain, there is a smaller and not quite significant difference in the opposite direction. Using a broader definition of pain severity based on several questions nearly doubles the number of subjects in the severe pain group and shows even more significant results. The relationship of predominant bowel pattern to HRV is qualitatively different in the subgroup of patients with more severe pain than in the subgroup with less severe pain.

Autonomic nervous system function in women with irritable bowel syndrome.

Autonomic nervous system (ANS) balance was assessed in women with and without irritable bowel syndrome (IBS) using laboratory tests of function (ie, expiratory/inspiratory ratio, Valsalva, posture changes, and cold pressor) and spectral and nonspectral measures of heart rate variability (HRV). Women with (N = 103) and without IBS (N = 49) were recruited, interviewed, then completed a laboratory assessment and wore a 24-hr Holter monitor Analysis using the entire sample showed little difference between IBS and control women and between subgroups with IBS on either laboratory measures or 24-hr HRV measures. However, analysis restricted to those women with severe IBS symptoms showed quite pronounced differences between two IBS subgroups on 24-hr HRV measures. Parasympathetic tone was significantly lower and ANS balance was significantly higher in the constipation-predominant compared to the diarrhea-predominant group. Subgroups of women with IBS do differ in ANS function as measured by 24-hr HRV; however, these differences are only apparent among women with severe symptoms. These findings point out the importance of considering symptom severity when interpreting studies of IBS.

Sleep disturbance influences gastrointestinal symptoms in women with irritable bowel syndrome.

This analysis evaluated the association between sleep disturbance and gastrointestinal symptoms in women with and without irritable bowel syndrome (IBS), and examined the role of psychological distress in this relationship. Women with IBS (N = 82) reported considerably higher levels of sleep disturbance compared to controls (N = 35), using both retrospective seven-day recall and daily diary recall for two menstrual cycles (P < 0.05 on 8 of 10 measures). We used daily diary data to estimate the association between sleep disturbance and gastrointestinal symptoms, both across women (ie, whether women with high average sleep disturbance have higher average gastrointestinal symptoms) and within woman (ie, whether poorer than average sleep on one night is associated with higher than average gastrointestinal symptoms the following day). The regression coefficients for the across-women effect are large and highly significant in both groups (IBS, beta +/- SE = 0.46 +/- 0.08, P < 0.001; controls, 0.57 +/- 0.13, P < 0.001). The regression coefficients for the within-woman effect are considerably smaller and statistically significant only in the IBS group (IBS, 0.06 +/- 0.02, P = 0.006; control, 0.01 +/- 0.03, P = 0.691). These regression coefficients showed little change when daily psychological distress or stress was controlled for, the one exception being the coefficient for the across-women effect in the IBS group, which decreased substantially but still remained highly significant. Because it is possible that gastrointestinal symptoms could, in fact, cause poor sleep, we also fitted the temporally reversed model to evaluate the association between gastrointestinal symptoms on one day and sleep disturbance that night. The within-woman regression coefficients were nonsignificant in both the IBS and control groups. In conclusion, these results are consistent with the hypothesis that poor sleep leads to higher gastrointestinal symptoms on the following day among women with IBS.

Bone resorption levels by age and menopausal status in 5,157 women.

OBJECTIVE: The purpose of this study was to describe bone resorption activity using a biochemical marker according to the categories of age, menopausal status, and selected drug/supplement use in middle-aged and elderly community-based women. DESIGN: This was a cross-sectional study that assessed urinary cross-linked N-telopeptide of type I collagen (NTx) and used self-report data to group women as premenopausal (Pre), perimenopausal (Peri), postmenopausal without hormone replacement therapy (Post), and postmenopausal with hormone replacement therapy (HRT). RESULTS: Mean NTx values were found to be significantly different by group and controlling for age (p = 0.001), with post hoc tests showing all pairwise group comparisons as significantly different (p = 0.001), except that the Pre and HRT groups were not significantly different. Both the Peri and the Post NTx levels were significantly higher than the Pre and the HRT groups'. NTx values in the Peri group varied with age-the youngest Peri women were similar to Pre women, and the oldest Peri women were similar to Post women. Significantly lower NTx levels were found only in the Post (p = 0.009) and HRT (p < 0.001) groups using diuretics compared with nonuse and only in the HRT group using calcium supplements compared with nonuse (p = 0.006). No differences by thyroid use were found. With a biochemical marker, the results showed that bone resorption activity differences could be demarcated in women according to age, estimated menopausal stage, and selected drug/supplement use. CONCLUSIONS: These results support the usefulness of NTx assessment for indicating bone resorption activity and therefore the potential for osteoporosis or for monitoring the efficacy of antiresorptive therapies.

Evidence for autonomic nervous system imbalance in women with irritable bowel syndrome.

Autonomic nervous system function was assessed in women with and without irritable bowel syndrome using frequency domain measures of heart rate variability. Women were interviewed and placed into the irritable bowel syndrome (N = 25) group based on history of diagnosis and self-report of current gastrointestinal symptoms. Women in the control group denied a history of chronic gastrointestinal symptoms (N = 15). Women were followed for one menstrual cycle with a symptom diary, and during mid-luteal phase they wore a Holter 24-hr electrocardiograph monitor. Women with irritable bowel syndrome demonstrated significantly lower vagal tone as measured by the high frequency spectrum relative to control women. In addition, women with irritable bowel syndrome had a flattened 24-hr pattern of heart rate variability, with significantly lower levels of vagal tone during sleep. These results suggest that systemic sympathovagal balance may be shifted in a subset of women with irritable bowel syndrome.