You can 'catch' depression and anxiety by kissing your partner; New study reveals shocking 'transmission'

“In sickness and in health.”

It’s not for nothing that these words are conventionally included in the standard wedding vows. Turns out, partners sometimes become way more than soulmates; at times, in sickness – especially in the case of mental health – they might share your health issues as well.

In a groundbreaking revelation, a recent study has revealed a surprising link between mental health and intimate acts between romantic partners. According to the study, your partner’s mental health could potentially impact yours through the mere act of kissing!


Read on to find out more about the ‘contagion’.


What does the study say?

As per a 2025 study of newlywed couples in Iran, published in Exploratory Research and Hypothesis in Medicine, your partner’s mental health could potentially impact your own through the exchange of oral bacteria. The study revealed that depression and anxiety can indeed be transmitted between partners through intimate interactions like kissing. This phenomenon, which was particularly highlighted in the research conducted amongst newlywed couples, showed that a mentally healthy spouse could start exhibiting signs of mental health issues after just six months of marriage to a partner struggling with depression.


The study followed the dynamics of 1,740 couples, all newly married for an average of six months. The research, led by independent researcher Reza Rastmanesh, focused on contrasting two groups: one consisting of 268 healthy spouses and another of 268 partners grappling with mental health challenges, including depression, anxiety, and sleep disturbances.


What are the findings?

At the start of the study period, the healthy spouses showed normal scores for depression, anxiety, and sleep quality. However, it became evident that after spending six months alongside a partner experiencing mental health issues, there was a marked deterioration in the mental well-being of the previously healthy individuals. Their mental health scores notably increased, reflecting symptoms of depression and anxiety, as well as sleep disturbances.


Analyzing their saliva samples through advanced DNA sequencing techniques, researchers discovered that the oral bacterial profiles of the healthy spouses mirrored those of their depressed partners.

This connection revealed that certain bacterial families, like Clostridia, Veillonella, Bacillus, and Lachnospiraceae, became more prevalent in both partners – which raised concerns due to their association with brain disorders such as depression and anxiety. As per the researchers, these bacteria might influence brain function by disrupting the blood-brain barrier, therefore compromising mental health.


What are the implications?

This groundbreaking study highlighted the profound impact of our microbiome, the vast community of microorganisms residing in our mouths, that we share with others through everyday activities such as kissing, sharing food, or even just being in close proximity.


The findings suggested that this microbial exchange could play a significant role in the transmission of mental health conditions. They also drew our attention to a significant gender difference in susceptibility to this bacterial transmission. Women, in particular, were found to be more vulnerable, as female partners exhibited more pronounced alterations in their oral microbiome and corresponding mental health scores than their male counterparts.

Moreover, the study monitored cortisol levels, the hormone associated with stress.

The results indicated that the stress response systems of healthy spouses married to partners with depression and anxiety were notably activated, as indicated by a substantial rise in cortisol levels over the six-month duration of the study. This accounts for the deep interconnection between partner relationships and mental health, underscoring the adage that we truly can “catch” our partner’s mood, not just emotionally – but also biologically.

Video