The microbiome is the collective name for the trillions of bacteria and other microorganisms that normally live peacefully in and on humans (the skin and the gut are major reservoirs), and many of which, through their rich array of genes , perform functions that support our existence in diverse ways. There are said to be 100 trillion bacteria residing in the gut alone. Some of them help humans dig
Why Does Microbiome Develop?
Understanding what causes microbiome is essential for prevention and treatment. Research consistently shows that microbiome arises from a complex interplay of biological, psychological, and social factors — rarely from a single cause.
What Researchers Have Found
Research into microbiome has identified multiple contributing pathways. Studies using neuroimaging, genetics, and longitudinal data reveal that no single factor fully explains why microbiome develops.
Biological Factors
Biological contributors to microbiome include:
- Genetics: Family history increases risk; certain genes influence vulnerability
- Brain chemistry: Neurotransmitter imbalances (serotonin, dopamine, norepinephrine) play key roles
- Brain structure: Differences in the prefrontal cortex, amygdala, and hippocampus are documented
- Physical health: Chronic illness, hormonal changes, and sleep disruption can trigger or worsen microbiome
Psychological Factors
- Early experiences: Childhood adversity, attachment disruption, and trauma shape psychological vulnerability
- Cognitive patterns: Negative thinking styles, perfectionism, and rumination increase risk
- Coping skills: Limited emotional regulation skills make microbiome more likely under stress
- Personality: Certain traits (neuroticism, harm avoidance) are associated with higher risk
Social and Environmental Factors
Environmental factors — including chronic stress, relationship problems, financial difficulty, and major life events — can trigger microbiome in vulnerable individuals.
What Triggers an Episode?
Even in people with predisposing factors, microbiome often requires a triggering event:
- Major life transitions (job loss, relationship breakdown, bereavement)
- Prolonged stress without adequate recovery
- Substance use or withdrawal
- Physical illness or injury
- Social isolation or conflict
Protective Factors
Not everyone with risk factors develops microbiome. Protective factors include: strong social support, effective coping skills, physical health maintenance, access to care, and psychological resilience built through prior challenges.