Petra Suchankova Karlsson of the University of Gothenburg in Sweden says in her thesis inflammation is part of the immune system and is responsible for defending humans against infection and healing of injuries.
However, the inflammatory processes also influence mechanisms in the brain involving learning and memory.
"Previous studies have shown that individuals suffering from various mental illnesses have an increased peripheral inflammation, but the reason behind this increase is not known," Suchankova Karlsson says in a statement.
"It has been suggested that the stress that goes with mental illness activates the body's immune system, but it is also possible that inflammation in the body affects the brain, which in turn results in mental illness."
Suchankova Karlsson's thesis suggests several different genes linked to the immune system are associated with healthy people's personality traits, buy it also demonstrates some genes are linked to an increased risk of schizophrenia or suicidal behavior.
"One of the things we studied was a gene variant that increases impulsiveness in people who carry it," Suchankova Karlsson says. "We found that these patients more often carried the particular gene variant when compared to the general population which meant that this variant was not only associated with increased impulsiveness in healthy individuals but also with increased risk of suicidal behavior."