Our aim is to explain the lack of clarity in the ways in which anxiety and depression, which are common in defecatory disorders (DD), may contribute to the disorder. In this study, we evaluate the effects of mental stress and relaxation on anal pressures and the mechanisms thereof.
In 38 healthy women and 36 DD patients, rectoanal pressures were assessed at rest and during mental stressors (ie, word-color conflict [Stroop] and mental arithmetic tests) and mental relaxation, before and after randomization to placebo or the adrenergic α1 -antagonist alfuzosin.
During the baseline Stroop test, the anal pressure increased by 6 ± 13 mm Hg (mean ± SD, P = 0.004) in healthy women and 9 ± 10 mm Hg (P = 0.0001) in constipated women. During mental arithmetic, the anal pressure increased in healthy (4 ± 8 mm Hg, P = 0.002) and constipated women (5 ± 9 mm Hg, P = 0.004). After relaxation, anal pressure declined (P = 0.0004) by 3 ± 4 mm Hg in DD patients but not in controls. Alfuzosin reduced (P = 0.0001) anal resting pressure (by 31 ± 19 mm Hg) vs placebo (16 ± 18 mm Hg). However, during the postdrug Stroop test, anal pressure increased (P = 0.0001) in participants who received alfuzosin but not placebo.
In healthy controls and DD patients, mental stressors likely increased anal pressure by contracting the internal anal sphincter; relaxation reduced anal pressure in DD patients. Alfuzosin reduced anal resting pressure but did not block the Stroop-mediated contractile response, which suggests that this response is not entirely mediated by adrenergic α1 receptors.