How kissing can actually spread depression and anxiety: study

Baby got bac!We all know that kissing and other close contact can transmit infections like the common cold, mononucleosis and herpes.A new study out of Iran suggests that depression and anxiety might be transmissible through kissing, too.Depression and anxiety can trigger the release of the stress hormone cortisol, which can disrupt the delicate balance of bacteria in the mouth.Spouses can transfer this bacteria while smooching — in fact, prior research found that as many as 80 million bacteria are transferred in just one 10-second kiss.The authors of the new study found that when one spouse had poor mental health and trouble sleeping, the healthy partner suffered similar symptoms after just six months.Bacteria were to blame.“Specifically, in couples where one partner had [depression/anxiety], the oral microbiota of the healthy spouse mirrored that of the affected partner,” the researchers wrote in the Exploratory Research and Hypothesis in Medicine journal.The team followed 268 newlywed Iranian couples.

One set of the honeymooners reported struggling with depression, anxiety and sleep problems while their spouses were healthy at the start of the study.Participants completed surveys about their mental health and provided saliva samples for cortisol measurement and oral bacteria swabs for DNA analysis.The researchers reported that the healthy spouses, particularly women, had significant increases in depression, anxiety and sleep difficulties after six months.These symptoms were not as intense as their partners’.Four types of bacteria — Clostridia, Veillonella, Bacillus and Lachnospiraceae — were relatively abundant in the samples.

Some species of these bacteria may be harmful to health.The researchers acknowledged several limitations to the study, including not taking into account underlying health issues and dietary factors that may influence oral bacteria.They suggest exploring whether bacteria play a role in other mental and brain-related conditio...