Study shows kissing may transmit depression and anxiety

A recent study published in the journal Exploratory Research and Hypothesis in Medicine suggests that kissing may contribute to the spread of depression and anxiety between partners. Conducted by independent researcher Reza Rastmanesh and a team from various countries including Italy, India, Iran, and Great Britain, the study focused on the oral microbiome of 268 newly married couples in Iran.

The researchers aimed to explore whether the exchange of oral bacteria between spouses could influence mental health symptoms. They conducted the study between February and October 2024, observing couples where one partner was in good mental health while the other experienced anxiety, depression, and insomnia.

On the first day of the study, researchers collected saliva samples to measure cortisol levels and analyzed the participants’ oral microbiomes using advanced DNA sequencing techniques. After six months, they repeated these measures and compared the results.

Findings indicated that previously healthy partners exhibited higher levels of depression, anxiety, and insomnia compared to their initial assessments. Specifically, their oral microbiome began to resemble that of their partner who was struggling with mental health issues. Researchers identified an increase in bacteria such as Clostridia, Veillonella, Bacillus, and Lachnospiraceae in both partners, which are associated with brain disorders and sleep disturbances.

The study also noted a rise in cortisol levels among the formerly healthy partners, linking the bacterial exchange through kissing to changes in mental health. The researchers concluded that the bacteria transferred during intimate contact could play a role in mediating symptoms of depression and anxiety.

However, the authors acknowledged limitations in their research, including the focus on Persian-speaking couples in Iran and the exclusion of other influencing factors like major life changes and diet. They stressed the need for further research to determine if the observed associations are indeed causal.

If validated, these findings could reshape our understanding of how close physical relationships may impact mental health, highlighting the importance of oral health in emotional well-being.