Abstract
Hypertension and depression affect substantial proportions of the population, especially older individuals. They correlate with significant changes in the gut microbiome, implicating microbiome composition as a possible therapeutic target. However, little exploration has been done on gut microbiome diversity and composition between hypertension and depression comorbidities. It is unknown how demographic variables such as age and sex affect microbiome diversity, particularly in the context of hypertension and depression comorbidities. We aimed to characterize the compositional changes in the gut microbiome between hypertension-only, depression-only and hypertension and depression comorbidities when stratified by sex and age. Using a 16S rRNA amplicon sequencing dataset, we conducted alpha diversity, beta diversity, taxonomic abundance, differential abundance and functional pathways analysis to determine the differences between the three health conditions, as well as sample stratification by sex and by age. Patients 60 years of age and over showed significant differences in their gut microbiome between conditions. An increase in evenness compared to control, which were patients without hypertension or depression, was found in the hypertension and hypertension and depression comorbidities, leading to the conclusion that a decrease in beneficial taxa, such as Faecalibacterium, occurred in healthy controls, along with an increase in rarer taxa. However, the enriched taxa in hypertension, depression and hypertension and depression cohorts showed both similar and opposing differential abundance to what was previously published. Studies using clinical diagnosis with larger sample sizes would benefit further exploration of microbial changes that occur in older patients with hypertension, depression and hypertension and depression comorbidity.