They cite work showing that "oral microbiota dysbiosis is significantly correlated with various neuropsychiatric disorders, including autism spectrum disorder,

They cite work showing that "oral microbiota dysbiosis is significantly correlated with various neuropsychiatric disorders, including autism spectrum disorder, dementia, Parkinson’s disease, schizophrenia, anxiety, epilepsy, and depression." No claims are made that oral microbiota cause depression and anxiety. I find it easy to believe that after marriage, couples converge in depression and anxiety absent any kissing. And because of kissing, their oral microbiota will also converge. But that doesn't imply that kissing is the cause of the convergence in depression and anxiety. Maybe I am missing something.