Can the gut microbiome influence personality?

Chemicals from the gut have complex interactions with the rest of the body

Trillions of bacteria live in our guts, producing a wide range of molecules, hormones, and more. This review underscores the immune system’s pivotal role in the microbiota–gut–brain axis. Gut microbes influence immune cells and metabolites, which in turn modulate neurodevelopment, neural signaling, mood, and neuroinflammation—highlighting immune pathways as central mediators in gut‑brain communication.

How the microbiome affects your health

The gut microbiome is so influential to overall human health that some researchers consider it a separate organ. Its conditions, influenced by environmental and lifestyle factors such as medication and exercise, contribute to immunity, metabolism, inflammation, medical treatment efficacy, brain development and function, and the development of disorders and diseases, including asthma, depression, inflammatory bowel disease, and Alzheimer's.

Listen to how the gut microbiome influences your emotions

The gut-microbiome connection may involve the enteric nervous system, a collection of hundreds of millions of neurons throughout the gut that transmit signals up the vagus nerve to the brain.

Bacteria in our intestine influence the brain via the gut-brain axis

The gut-brain axis refers to the physical connection between the central nervous system and the digestive tract. Signaling molecules and hormones produced in the gut directly affect brain functions via this internal highway.

Can the gut microbiome drive addiction?

New research suggests an imbalance of gut microorganisms may influence the likelihood of addiction and addictive behaviors by increasing the severity of withdrawal symptoms, triggering brain inflammation in regions of impulse control, and more.

The gut microbiome's role in chronic diseases

Research shows that the microbial makeup of one's gut microbiome is associated with chronic diseases ranging from asthma to schizophrenia. Understanding these associations may reveal new ways to prevent or treat chronic diseases. In the meantime, nutritional changes—such as including more dietary fiber and unsaturated fat—appear to be the "most obvious, noninvasive, and immediate" way to alter the gut's microbiota makeup and functions.

Some dementia cases may be linked to microorganisms in the brain

Researchers now know that, much like the gut, the brain is home to an ecosystem of microorganisms—the brain microbiome. While this area of study is still new, some scientists believe 50% of bacteria-caused dementia cases could be treated. (Some users may encounter a paywall.)

What happens when the gut microbiome is out of whack?

An imbalance in gut microbiome flora can lead to a condition known as dysbiosis. This condition is typically characterized by a drop in microbiota diversity and an increase in harmful unicellular and acellular organisms, such as viruses, that can negatively impact the host's immune system and overall health. Genetics, infections, dietary choices, antibiotics, food additives, artificial sweeteners, and other lifestyle and environmental factors can cause dysbiosis.

What is the gut virome?

The gut microbiome's community of viruses is collectively known as the virome. It has been found to affect immune system development—important to the gut-brain axis—and has been implicated in the development of inflammatory bowel disease and Type 2 diabetes. As of early 2023, less than half of the viral sequences in the gut had been identified. Further study is needed to understand the virome's influence and therapeutic potential.

How the gut microbiome can affect heatstroke risk

Some research suggests that our gut microbiome influences our risk of exertional heatstroke. If exercise boosts our body temperatures to unsafe levels, increasing gut permeability, that can cause a "leaky" gut—allowing bacteria and other gut microbes to leak into the bloodstream and potentially trigger endotoxemia, a potentially life-threatening inflammatory response that can occur with heat exhaustion and heatstroke.

Some animals have little or no bacterial populations in their gut

Gut microbiomes are essential to human health, but many animals have a much smaller, transient, or even nonexistent microbiome. The discoveries have advanced our understanding of the evolution of the human microbiome.

What's next for gut microbiome science?

A Stanford microbiologist explores what we don't yet know about the gut microbiome—such as whether we can engineer the bacterial species within it—and the current scientific advances in the field.

Can microdosing improve mental health?

Animal studies involving microdoses of psilocybin, the psychoactive component in magic mushrooms and ketamine, found it helped to alleviate anxiety and inflammation, an immune response that can cause damage when chronically active. Human studies are ongoing. In at least one double-blind study, where researchers and patients don't know who got a placebo versus the real thing, about half of the participants incorrectly guessed they had been given placebos.

Inflammation appears to cause specific symptoms of depression

A large analysis of existing studies published in 2021 found that systemic inflammation is associated with fatigue, appetite changes, and sleep disruption, rather than some of depression's broader symptoms including hopelessness about the future, or feeling fearful. This may suggest that inflammation influences specific symptoms of the condition, rather than the disease as a whole.

Are probiotics a scam?

Probiotics are microbes meant to benefit the gut microbiome's health when consumed. This internal cityscape is packed with thousands of species of microbes whose roles and impacts have yet to be untangled. The odds are low that the probiotics have the effects they're marketed to have, and most of the gut helpers on grocery shelves have little to no evidence of impacting gut microbiome health.

JJ Schildkraut theorized depression is linked to brain chemical imbalances—in 1965

Schildkraut was one of the first to put forward this idea, which stemmed from lab animal research. A decade later, researchers published the first landmark paper on fluoxetine—better known by trade name Prozac—which increases serotonin levels in the brain.

Circadian rhythm disruption can influence various mental health disorders

This 2020 research overview surveys the relationship between disrupted circadian clocks and disorders including schizophrenia, anxiety, and bipolar disorder. It incorporates findings and therapeutic approaches drawing from human night shift studies and jet lag studies alongside animal research.

Scientists seeking gut insights are attaching flatulence sensors to volunteers' underwear

This fart-tracking device detects gas generated in the gut, providing insights about gut microbial activity. The underwear sensors measure a component of what is technically called flatus—digestive system gas.

Stress can be contagious—and scientists want to learn more about it

Researchers have shown that being around someone who is stressed can trigger a stress response in your body, such as elevated cortisol levels and elevated heart rate. One way this was recently studied was by having people watch stressful activities, like a recorded job interview or solving challenging math problems, and then sampling hormones in observers' spit.

Yoga is believed to improve mental health, but studies are not definitive

Many think that yoga's combination of stretching, focused breathing, and contemplation help treat depression and anxiety, but the data has often relied on small, homogenous sample sizes.

Could all mental health disorders have a unifying 'p-factor'?

Some researchers have argued in the past couple decades that all mental health disorders may have a unifying dimension—a theoretical "p-factor" that is common across mental illness, but life experiences and behaviors influence if and how illness manifests. Proponents point to similarities across different disorders, while detractors argue that such connections are largely exaggerated.

How frontotemporal dementia changes your personality

Significant changes in personality later in life are often attributed to psychological factors. But Dr. Bruce Miller, long-time researcher of FTD, argues this shift is most often attributable to changes in the brain.

Can music alter your memories?

You’re familiar with music’s ability to transport you to a past experience, but new research suggests that music can even alter how you remember your past experiences. A team of psychology researchers and music experts recently published a study that demonstrates how music can help shift our emotional recollection of a memory. Read to learn more about the study’s findings and how it could influence therapy practices.

Studies suggest only 9% of a dog's personality comes from its breed

While all dogs descend from wolves domesticated and bred for specific tasks by humans at least 15,000 years ago, most behavioral characteristics result from a mix of genetics and environment, which result in diverse canine dispositions within the same breed.

How menopause affects mental health

Menopause, a natural biological process, occurs in three stages: perimenopause (hormone fluctuations), menopause (end of menstrual cycles), and postmenopause (12 months without menstruation). Hormonal shifts during this time can affect neurotransmitters, increasing the risk of mood disorders.

Hookworm infection, though risky, may help fight certain autoimmune conditions by tamping down the immune system's inflammatory response.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

About 12.5% of US adults experience a phobia in their lifetime, a diagnosis that hinges on the intense fear interfering with daily life and persisting for at least six months.

Explore an interactive map built from more than 100,000 survey responses on where people find joy in their lives

Read a deep dive on the 'all-purpose healing' peptide BPC-157.

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

The hormonal disorder PCOS was renamed PMOS in 2026, a move designed to improve care and research by shifting the focus to the hormonal causes of this condition that affects 1 in 8 women.

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

Coral reefs get their colors from zooxanthellae—microorganisms that line corals' digestive tracts and provide them with sugars in exchange for a home within this protective tissue.

Use this calculator to find the dollar value of your mental load, from meal planning to coordinating after-school care for your children.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

Astronauts have repaired genetic damage in space using CRISPR—a molecular tool that can make precise changes to DNA and is used in single-celled organisms to attack invasive viruses.

An investigation suggests a Scottish island became awash in forever chemicals via seafoam and seaspray—raising questions about what that means for the safety of other coastal areas.

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

SpongeBob exemplifies Aristotle's philosophy for living well because he understands that happiness doesn't come from external factors like money, recognition, or power.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

After her fellow cult members tried to kill her with an LSD-infused hamburger, one member of the Manson Family, the murderous cult led by Charles Manson, decided to testify against the group's leader.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

Clever Hans was a 1900s horse that was believed to be able to solve math equations, tell time, and read and comprehend German, until a psychology student discovered how he got his answers.

Poison ivy is in the same family as mangoes, cashews, and pistachios—and they all produce oily urushiol in their raw, unprocessed state—but they are typically prepared in ways to avoid causing human discomfort.

Fast-casual restaurant Chili's is experiencing a resurgence, with its parent company recently reporting a nearly 32% increase in sales, thanks to passionate Gen Z fans on TikTok.

The price of gas is a composite made up of several different factors, with the federal gas tax making up less than 20% of what drivers pay at the pump.

The power and influence of the American presidency have expanded significantly over time—far beyond what the founders envisioned.

One of the most famous portraits ever taken is 'Afghan Girl' (1984) by Steve McCurry, yet the subject Sharbat Gula went much of her life without being identified or benefitting from the image's success.