The intestinal microbiota as a predictor for antidepressant treatment outcome in geriatric depression: a prospective pilot study.

OBJECTIVES: (1) To investigate if gut microbiota can be a predictor of remission in geriatric depression and to identify features of the gut microbiota that is associated with remission. (2) To determine if changes in gut microbiota occur with remission in geriatric depression. DESIGN: Secondary analysis of a parent randomized placebo-controlled trial (NCT02466958). SETTING: Los Angeles, CA, USA (2016-2018). PARTICIPANTS: Seventeen subjects with major depressive disorder, over 60 years of age, 41.2% female. INTERVENTION: Levomilacipran (LVM) or placebo. MEASUREMENTS: Remission was defined by Hamilton Depression Rating Scale score of 6 or less at 12 weeks. 16S-ribosomal RNA sequencing based fecal microbiota composition and diversity were measured at baseline and 12 weeks. Differences in fecal microbiota were evaluated between remitters and non-remitters as well as between baseline and post-treatment samples. LVM and placebo groups were combined in all the analyses. RESULTS: Baseline microbiota showed no community level α-diversity or ß-diversity differences between remitters and non-remitters. At the individual taxa level, a random forest classifier created with nine genera from the baseline microbiota was highly accurate in predicting remission (AUC = .857). Of these, baseline enrichment of Faecalibacterium, Agathobacter and Roseburia relative to a reference frame was associated with treatment outcome of remission. Differential abundance analysis revealed significant genus level changes from baseline to post-treatment in remitters, but not in non-remitters. CONCLUSIONS: This is the first study demonstrating fecal microbiota as a potential predictor of treatment response in geriatric depression. Our findings need to be confirmed in larger prospective studies.

Mindfulness Training Improves Cognition and Strengthens Intrinsic Connectivity Between the Hippocampus and Posteromedial Cortex in Healthy Older Adults.

Maintaining optimal cognitive functioning throughout the lifespan is a public health priority. Evaluation of cognitive outcomes following interventions to promote and preserve brain structure and function in older adults, and associated neural mechanisms, are therefore of critical importance. In this randomized controlled trial, we examined the behavioral and neural outcomes following mindfulness training (n = 72), compared to a cognitive fitness program (n = 74) in healthy, cognitively normal, older adults (65-80 years old). To assess cognitive functioning, we used the Preclinical Alzheimer Cognitive Composite (PACC), which combines measures of episodic memory, executive function, and global cognition. We hypothesized that mindfulness training would enhance cognition, increase intrinsic functional connectivity measured with magnetic resonance imaging (MRI) between the hippocampus and posteromedial cortex, as well as promote increased gray matter volume within those regions. Following the 8-week intervention, the mindfulness training group showed improved performance on the PACC, while the control group did not. Furthermore, following mindfulness training, greater improvement on the PACC was associated with a larger increase in intrinsic connectivity within the default mode network, particularly between the right hippocampus and posteromedial cortex and between the left hippocampus and lateral parietal cortex. The cognitive fitness training group did not show such effects. These findings demonstrate that mindfulness training improves cognitive performance in cognitively intact older individuals and strengthens connectivity within the default mode network, which is particularly vulnerable to aging affects. Clinical Trial Registration: [https://clinicaltrials.gov/ct2/show/NCT02628548], identifier [NCT02628548].

Compassionate Hearts Protect Against Wandering Minds: Self-compassion Moderates the Effect of Mind-Wandering on Depression.

Depression is associated with high levels of mind-wandering and low levels of self-compassion. However, little is known about whether and how these two factors interact with one another to influence depressive symptoms. The current study examined the interaction between mind-wandering, self-compassion and depressive symptoms in a depressed sample and tested the effects of an eight-week Mindfulness Based Cognitive Therapy (MBCT) program on these constructs. At baseline, mind-wandering was associated with higher depressive symptoms only among individuals with low self-compassion. Self-compassion additionally predicted depressive improvement. As expected, MBCT increased self-compassion and reduced mind-wandering compared to a treatment-as-usual control group. Overall, longitudinal changes in self-compassion produced a moderation effect similar to the one at baseline so that increases in mind-wandering were associated with increases in depressive symptoms only among those who decreased in self-compassion. Results provide the first evidence that self-compassion can protect against the deleterious effects of mind-wandering among depressed participants, both at baseline and longitudinally. Findings also suggest that self-compassion is an effective predictor of depressive improvement. Finally, MBCT is effective not only at reducing depressive symptoms, but also at targeting protective and risk factors associated with depression.