Getting dirty may lift your mood
14 June 2007
Identifying how the immune system can signal to the brain to influence behaviour and emotional state.
The authors hypothesise that this small group of serotonin neurons normally increases the ability to cope with stressful life events, but when the system is over-activated, for example by prolonged immune activation or chronic stress, it can desensitise, leading to an inability to effectively cope with everyday stress (a common feature of major depression). The work raises interesting questions relating to how the body communicates with the brain to regulate our behaviour and our emotions. It also help us understand how the body communicates with the brain and why a healthy immune system is important for maintaining mental health.
This research makes us wonder if we shouldn't spend more time playing in the dirt
The interest in M.vaccae arose following its discovery in soil samples from the shores of Lake Kyoga in Uganda when colleagues were looking for a bacterium that could help the human immune system respond to virulent bacteria like M. tuberculosis, which causes tuberculosis. Subsequently, they found that M. vaccae was also an effective vaccine for leprosy and could improve the autoimmune symptoms of leprosy patients free from bacterial infection. Since then, M. vaccae-based products have been evaluated in clinical trials for the treatment of asthma, cancer and tuberculosis.
Interest in the antidepressant qualities of M.vaccae emerged after human cancer patients treated with M. vaccae unexpectedly reported increases in their quality of life. Lowry and his colleagues reasoned that this effect could be mediated by activation of serotonin-containing neurons in the brain. The new research supports this hypothesis but future studies will be designed to determine if M. vaccae or other bacteria have antidepressant properties, through activation of this group of serotonin neurons.