A new research report sheds fresh light on the processes in the brain that can lead to suicide. In tests on patients who have previously tried to take their own lives, researchers have measured high levels of quinolinic acid, a substance that strengthens glutamate signalling in the brain. Quinolinic acid is formed in the brain as a by-product of inflammation.
Swedish researchers have now presented new research findings that show that glutamate, which is also believed to play a role in depression, is linked to suicidal tendencies. Lena Brundin from Lund University and Sophie Erhardt from Karolinska Institutet have spent several years studying how inflammation can lead to mental illness, and the study is a result of these projects.
“The findings are very important because they show a chemical disease mechanism in the patients. There has been a major focus on another signal substance, serotonin, for 40 years. Our conclusions suggest that it is time to shift some of the focus to glutamate”, says Lena Brundin.
The researchers studied the activity of glutamate by measuring quinolinic acid – a chemical substance that increases the signal strength in the glutamate system – in the spinal fluid of 100 people. Around two thirds of the participants had been admitted to hospital following a suicide attempt, while the remainder were healthy. The results showed that the levels of quinolinic acid in the suicidal patients were over twice as high as those in the healthy subjects. The patients who were reported to show the most pronounced suicidal behaviour also had the highest levels.
“Anti-glutamate drugs are still under development and could become an important tool to prevent suicides. New clinical studies have shown that the anaesthetic substance ketamine, which blocks glutamate signalling, appears to be very effective against depression, even if its side-effects limit its application at present”, says Lena Brundin.
The research report, ‘Connecting inflammation with glutamate agonism in suicidality’, is a collaboration between researchers from Sweden, the USA and Australia.
Authors: Sophie Erhardt, Chai K. Lim, Klas R. Linderholm, Shorena Janelidze, Daniel Lindqvist, Martin Samuelsson, Kristina Lundberg, Teodor T. Postolache, Lil Träskman-Bendz, Gilles J. Guillemin and Lena Brundin.
Title: ‘Connecting inflammation with glutamate agonism in suicidality’ Neuropsychopharmacology, 2012; doi: 10.1038/npp.2012.248
Link to article