The Potential Impact of Age on Gut Microbiota in Patients with Major Depressive Disorder: A Secondary Analysis of the Prospective Observational Study

Abstract

We aimed to investigate the impact of aging on the relationship among the composition of gut microbiota, gastrointestinal (GI) symptoms, and the course of treatment for major depressive disorder (MDD) by analyzing the datasets from our previous study. Patients with MDD were recruited, and their stools were collected at three time points (baseline, midterm, and endpoint) following the usual antidepressant treatment. Gut microbiota were analyzed using 16S rRNA gene sequencing. Patients were categorized into two groups based on their age: the late-life group over 60 years and the middle-aged group under 60 years. GI symptoms were assessed with scores of item 11 of the Hamilton Anxiety Rating Scale. One hundred and ninety samples were collected from 32 patients with MDD. Several gut microbes had higher relative abundances in the late-life group than in the middle-aged group. In addition, the late-life group showed significantly higher diversity in the Chao1 index at baseline compared with the middle-aged group. We further found possible microbial taxa related to GI symptoms in patients with late-life depression. The abundance of several bacterial taxa may contribute to GI symptoms in the late-life depression, and our findings suggest that the therapeutic targets for the application of gut microbiota may differ depending on the age group of patients with depression.

The relationship between sleep, gut microbiota, and metabolome in patients with depression and anxiety: A secondary analysis of the observational study

“…In support of our finding, Li et al [ 32 ] reported an increased relative abundance of Bacteroides in insomnia patients compared with HCs; in contrast, another previous studies showed a lower proportion of Bacteroides in the insomnia group compared with HCs [ 34 , 50 ]. These discrepancies could be due to differences in the methods of genetic analysis (e.g., 16S rRNA sequencing, region, qPCR) and age of target subjects (i.e., young, middle-aged) [ 21 ]. Given that the correlation between sleep conditions and the gut microbiota remains controversial, further studies focusing on the relationship between the gut microbiota and sleep in patients with psychiatric disorders are needed.…”

“…First, the sample size of this study was small. To evaluate the more complex associations between gut microbiomes/metabolomes and sleep, and to avoid beta errors, a large cohort study would be necessary [ 14 , 20 , 21 ]. Second, we did not consider the impact of environmental factors on the composition of gut microbiota in each patient.…”

“…In this study, only data from the baseline assessment was used. The longitudinal data from the midterm and endpoint assessments was presented in our previous papers [ 14 , 20 , 21 ].…”