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TEHRAN \u2014<\/strong> Marriage means sharing your life with someone special. But new research out of Iran reveals couples might be sharing more than they bargained for: the bacteria in their mouths \u2014 and potentially their mental health struggles along with it.<\/p>\n A study of newlywed couples in Iran found that when one spouse suffers from depression and anxiety, their partner\u2019s oral bacteria actually changes to mirror theirs. As those microbes shift, so do the healthy partner\u2019s mood and sleep patterns.<\/p>\n After just six months of marriage<\/a>, previously healthy spouses showed significantly higher rates of depression, anxiety, and sleep problems if their partner had what researchers called the \u201cdepression-anxiety phenotype\u201d \u2014 essentially, someone dealing with both conditions simultaneously along with insomnia.<\/p>\n \u201cOral microbiota transmission between individuals in close contact partially mediates symptoms of depression<\/a> and anxiety<\/a>,\u201d the researchers concluded in their paper published in\u00a0Exploratory Research and Hypothesis in Medicine<\/a>. The journal notes that exploratory research published by it \u201cdoes not necessarily need to be comprehensive and conclusive, but the study design must be solid, the methodologies must be reliable, the results must be true, and the hypothesis must be rational and justifiable with evidence.\u201d<\/p>\n How Bacteria Jump Between Partners<\/p>\n Every time you kiss your spouse<\/a>, share a meal, or breathe the same air in close quarters, you\u2019re potentially swapping millions of bacteria. Most bacterial exchange is harmless or even beneficial. But this study points to a pathway for mental health conditions to spread between intimate partners.<\/p>\n The research team, led by independent researcher Reza Rastmanesh, tracked couples married for an average of six months. They recruited 1,740 couples from two private sleep clinics in Tehran between February and October 2024, comparing 268 healthy spouses with 268 partners who had depression, anxiety, and sleep problems. Both groups took standardized mental health tests, provided saliva samples to measure stress hormones, and had their mouth bacteria analyzed using advanced DNA sequencing techniques.<\/p>\n At the study\u2019s start, healthy spouses scored normally on tests for depression, anxiety, and sleep quality<\/a>. After six months of living with an affected partner, their scores climbed significantly higher \u2014 not quite matching their troubled spouse, but moving in that direction.<\/p>\n Can depression or anxiety really be transmitted through a kiss? New research suggests the swapping of oral bacteria could make it possible (Photo by PeopleImages.com \u2013 Yuri A on Shutterstock)<\/p>\n More revealing was what happened to their mouth bacteria<\/a>. The oral microbiome\u2014the community of microorganisms living in our mouths\u2014of healthy spouses began resembling that of their depressed and anxious partners. Using a technique called linear discriminant analysis, researchers found that specific bacterial families like Clostridia, Veillonella, Bacillus, and Lachnospiraceae became more abundant in both partners.<\/p>\n These bacteria aren\u2019t random. Previous research has linked these same microorganisms to brain disorders, including depression, anxiety, and sleep disturbances. Scientists believe these bacteria may affect the brain by compromising the blood-brain barrier<\/a> or through what\u2019s called the \u201coral microbiota-brain axis\u201d\u2014essentially, a pathway of communication between mouth bacteria and the brain.<\/p>\n Women Show Stronger Effects<\/p>\n Female spouses appeared more susceptible to these changes than men, showing more pronounced increases in depression, anxiety, and sleep problems after six months, along with greater shifts in their oral bacteria composition.<\/p>\n The study also measured cortisol<\/a>, often called the \u201cstress hormone,\u201d in participants\u2019 saliva. Healthy spouses married to depressed and anxious partners showed significant increases in their cortisol levels over six months, indicating their stress response systems were being activated.<\/p>\n This bacterial transmission theory builds on existing research showing how couples synchronize biologically \u2014 their heart rates can align during conversations, sleep patterns often mirror each other, and they share similar daily cortisol rhythms. What\u2019s new here is the suggestion that mental health<\/a> conditions might spread through bacterial exchange.<\/p>\n What This Means for Treatment<\/p>\n These findings could reshape how we think about treating depression and anxiety in relationships. Instead of focusing solely on the individual patient, healthcare providers might need to consider the couple as a unit, potentially treating both partners even when only one shows obvious symptoms.<\/p>\n The research builds on compelling evidence from animal studies where scientists successfully transferred depression-like behaviors to healthy mice by transplanting gut bacteria from depressed animals. Other studies show that probiotics<\/a>\u2014beneficial bacteria\u2014can improve mood and reduce anxiety in both animals and humans.<\/p>\n Of course, this study has limitations. Researchers only followed couples for six months and didn\u2019t account for other factors like shared stress from major life events, similar diets, or lifestyle changes that come with marriage. Participants were also aware they were being studied, which could have influenced their responses to mental health questionnaires.<\/p>\n The research was conducted in Iran with Persian-speaking couples, so findings might not apply universally. While the study found strong correlations between bacterial changes and mental health symptoms, it can\u2019t definitively prove the bacteria caused the mood changes\u2014just that they occurred together.<\/p>\n For couples, the findings offer both concern and hope. While no one wants to think they might \u201ccatch\u201d their partner\u2019s depression<\/a>, understanding this potential mechanism could lead to better treatments. If bacterial imbalances contribute to mental health problems, then targeted probiotics or other microbiome interventions might offer new therapeutic options.<\/p>\n The research also reinforces what marriage counselors and therapists have long observed\u2014that mental health conditions affect entire families, not just individuals. This study provides biological evidence for that clinical experience.<\/p>\n![\"Newlywed](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2025\/05\/Newlywed-couple-kissing-1200x800.jpg\"\/)
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