Reduction in salivary α-amylase levels following a mind-body intervention in cancer survivors--an exploratory study

Abstract

Objective: The main aim of this exploratory study was to assess whether salivary α-amylase (sAA) and salivary cortisol levels would be positively modulated by sleep-focused mind-body interventions in female and male cancer survivors.

Methods: We conducted a randomized controlled trial in which 57 cancer survivors with self-reported sleep disturbance received either a Sleep Hygiene Education (SHE; n=18) control, or one of two experimental mind-body interventions, namely, Mind-Body Bridging (MBB; n=19) or Mindfulness Meditation (MM; n=20). Interventions were three sessions each conducted once per week for three consecutive weeks. Saliva cortisol and sAA were measured at baseline and 1 week after the last session. Participants also completed a sleep scale at the same time points when saliva was collected for biomarker measurement.

Results: Our study revealed that at post-intervention assessment, mean sAA levels upon awakening ("Waking" sample) declined in MBB compared with that of SHE. Mean Waking cortisol levels did not differ among treatment groups but declined slightly in SHE. Self-reported sleep improved across the three interventions at Post-assessment, with largest improvements in the MBB intervention.

Conclusion: In this exploratory study, sleep focused mind-body intervention (MBB) attenuated Waking sAA levels, suggesting positive influences of a mind-body intervention on sympathetic activity in cancer survivors with sleep disturbance.

Trial registration: ClinicalTrials.gov NCT00935376.

Keywords: Biomarker; Cancer survivor; Mind–body intervention; Salivary cortisol; Salivary α-amylase; Sleep disturbance; Stress; Sympathetic nervous system.

Copyright © 2013 Elsevier Ltd. All rights reserved.

Figures

Figure 1

Baseline mean (and SEM) levels of sAA (closed circles) and salivary cortisol (closed squares) depicting changes in biomarker levels across a 24-hr period, comprising four collections on Day 1, Post-awake (30 min after awakening), Noon, Afternoon (5 pm), Evening (before bedtime, ~10 pm) and the fifth sample collected upon awakening (Waking) on the following day, Day 2, as separated by the vertical dotted line (see main text for further information). The data represent baseline (PRE) levels for all 57 participants.

Figure 2a and b

Waking (a) sAA and (b) salivary cortisol levels showing sample means at PRE and POST (solid circles) and their standard errors (vertical bars) relative to the change expected in the absence of treatment effects (empty circles and dashed lines). The observed changes include the biasing effects of regression to the mean and chance baseline differences resulting from randomization. Arrows show magnitude and direction of systematic change corrected for this bias, and correspond to the estimated group treatment differences in the statistical analysis. Horizontal dashed line is overall observed mean at PRE. Figure shows raw values; statistical tests were based on log-transformed values to reduce skew and meet normal theory test assumptions. In Figure 2a, the mean Waking sAA level in MBB at POST was lower than that in SHE (p=.019, test of equal MBB and SHE treatment effect, see text).

Figure 3

MOS-SS Sleep Problems Index II scores showing sample means at PRE and POST (solid circles) and their standard errors (vertical bars) relative to the change expected in the absence of treatment effects (empty circles and dashed lines). The observed changes include the biasing effects of regression to the mean and chance baseline differences resulting from randomization. Arrows show magnitude and direction of systematic change corrected for this bias, and correspond to the estimated group treatment differences in the statistical analysis. Horizontal dashed line is overall observed mean at PRE. While all interventions indicated significant reductions in sleep problems at POST, MBB was lower than SHE (p=.001, test of equal MBB and SHE treatment effect, see text).