Infections up risk of mood disorders

A new research found that every third person who is diagnosed for the first time with a mood disorder has been admitted to hospital with an infection prior to the diagnosis

The study is the largest of its kind to date to show a clear correlation between infection levels and the risk of developing mood disorders.

Anyone can suffer from an infection, for example in their stomach, urinary tract or skin. It would now appear that their distress does not necessarily end once the infection has been treated.

"Our study shows that the risk of developing a mood disorder increases by 62 percent for patients who have been admitted to hospital with an infection. In other words, it looks as though the immune system is somehow involved in the development of mood disorders," said Michael Eriksen Benros, MD and PhD from Aarhus University and Psychiatric Centre Copenhagen.

The study is a register study, which has involved following more than 3 million Danes. Between 1977 and 2010, more than 91,000 of these people had hospital contact in connection with a mood disorder. It transpired that 32 percent of the patients had previously been admitted with an infectious disease, while 5 percent had been admitted with an autoimmune disease.

According to Benros, the increased risk of mood disorders can be explained by the fact that infections affect the brain.

"Normally, the brain is protected by the so-called blood-brain barrier (BBB), but in the case of infections and inflammation, new research has shown that the brain can be affected on account of a more permeable BBB," he stated.

Benros hopes that knowing more about this connection will help to prevent mood disorders and improve future treatment.

The findings have just been published in the prestigious international journal JAMA Psychiatry.