Deakin University researchers have found a connection between poor dental health and depression.
Using data from a comprehensive health survey of more than 10,000 people aged 20—75 years living in the United States, the Deakin IMPACT Strategic Research Centre researchers found that poor dental health (as measured by the number of dental conditions a person had) increased the likelihood of being depressed.
"Not only did we find a connection between dental health and depression, we also demonstrated that a dose-response exists between the two conditions, meaning that the more dental conditions one had the greater the severity of their depression," said Deakin's Dr Adrienne O'Neil.
"This relationship held true even after accounting for other factors that could potentially explain the association, such as high body mass index and CRP, a protein that is often used as a general marker of inflammation in the body."
Depression is considered an inflammatory disorder, meaning that sources of inflammation such as bad dietary habits, being overweight or the presence of other medical conditions can contribute to the biological processes that induce mental disorders from a very early age. Poor dental health, which is a source of inflammation, has not been investigated extensively in the context of its links with mental health. The researchers therefore analysed the data from the National Health and Nutrition Examination Survey from the United States to investigate the possible connection.
They found almost two thirds of participants reporting depression (61 per cent) also reported having an aching mouth in the past year and more than half (57.4 per cent) considered their teeth to be in fair or poor condition.
While the researchers were able to demonstrate that depression is linked to poor dental health, through this study they were not able to determine why.
"The relationship between dental health and depression is not well understood, with previous studies investigating poor dental health as a by-product of depression, rather than a precursor," Dr O'Neil said.
"Although the results of this study provide only a snapshot of this association, they add to emerging theories around the importance of oral health and bacteria in mental health.
"This is an exciting area of research Deakin is exploring further with longitudinal data collected here in Australia. Specifically, we are currently conducting a study of how microbiota and the bacteria in the mouth, as well as the gut, may be related to inflammatory disease, including depression.
"If poor dental health is a risk factor for depression, this may have implications for depression management, as well as depression prevention from a public health perspective."
The results of this study are published in the online version of the journal General Hospital Psychiatry.