If your partner has depression, anxiety you could ‘catch’ it by kissing them, says new study

A new research states that depression and anxiety can spread between married couples through shared mouth bacteria or kissing.

Did you know that you could get depression and anxiety from your partner through mouth bacteria? Did we stump you? Well, a new study found that depression and anxiety can spread between partners if they kiss - a healthy spouse could show mental health symptoms after just six months of marriage to a depressed partner.

Each time you kiss, share food, or simply breathe near your spouse, you exchange millions of bacteria - the new research shows that this microbial sharing may also contribute to the transmission of mental health conditions.

Depression gets transmitted between partners by kissing?

A 2025 study of newlywed couples in Iran - published in Exploratory Research and Hypothesis in Medicine - found that when a partner suffers from depression and anxiety, they could potentially change their healthy partner's oral bacteria, leading to a shift in the healthy partner's mood and sleep patterns. “Oral microbiota transmission between individuals in close contact partially mediates symptoms of depression and anxiety,” the researchers said in the paper.

Just six months into marriage, previously healthy spouses were significantly more likely to experience depression, anxiety, and sleep disturbances if their partner was someone who had both mental health conditions, along with insomnia.

The study

The research, led by independent researcher Reza Rastmanesh, tracked 1,740 couples married for an average of six months, comparing 268 healthy spouses with 268 partners who had depression, anxiety, and sleep problems. They took standardised mental health tests, provided saliva samples to measure stress hormones, and had their mouth bacteria analysed using advanced DNA sequencing techniques.

At the start of the six months, the healthy spouses scored normally on depression, anxiety, and sleep quality tests. However, after living with a partner with mental health issues, their scores were significantly higher. Their mouth bacteria resembled that of their depressed and anxious partners.

Bacterial families like Clostridia, Veillonella, Bacillus, and Lachnospiraceae became more abundant in both partners. The bacteria are linked to brain disorders, including depression, anxiety, and sleep disturbances. Scientists believe that they affect the brain by compromising the blood-brain barrier.

Women affected more

Additionally, researchers found that women were more susceptible to this bacterial transmission; female spouses experienced more pronounced changes in both their oral microbiome and mental health scores.

They also measured cortisol levels during the study and found that the stress hormone in healthy spouses married to depressed and anxious partners showed a significant increase over six months, indicating their stress response systems were being activated.

Note to readers: This article is for informational purposes only and not a substitute for professional medical advice. Always seek the advice of your doctor with any questions about a medical condition.