Journal Article Annotations
2017, 1st Quarter
Annotations by Natalia Ortiz, MD, FAPM, FAPA, and Allison McKimm, MD
Taking probiotics may decrease depressive symptoms by the proposed mechanism of decreasing inflammatory markers and/or increasing the availability of serotonin by increased production of free tryptophan.
This is a systematic review that analysed ten studies investigating the effects of taking probiotics on depressive symptoms. Three out of the five studies that assessed the effects of probiotics on mood reported improvement in mood symptoms. Five out of the seven studies that assessed the effects of probiotics on stress and anxiety reported improvement in stress/anxiety symptoms. Three out of three studies that assessed the effects of probiotics on cognition reported improved effects on cognition.
The review used a heterogeneous set of studies with inconsistent measures of depression and anxiety (various scales were used among the different studies). Seven out of the ten studies used a healthy control population, one study assessed a depressed population, and two studies assess patients with stress/chronic fatigue syndrome. There was no consistency in the strain, dose or duration of probiotic use.
The review explored the role of the effects of probiotics on psychiatric symptoms of depression, anxiety, and cognition. There is increased interest in investigating the “gut-brain-axis,” or the linkage between the GI tract and the CNS, ANS, ENS, neuroendocrine, and immune systems. The findings in the study suggest a possible beneficial relationship of the use of probiotics for these symptoms, with greatest effect seen in anxiety symptoms. There is increasing interest in investigating other therapies for depression and anxiety, as current therapy with antidepressants has its own set of limitations. Antidepressants may take weeks to take effect, side effects may contribute to compliance, and there may be a stigma associated with taking psychotropic medications.