A Missing Link: Serotonin, Inflammation and Psychiatric Illness
We have previously looked at the extraordinarily high rates of inflammation in psychiatric illnesses, as well as the evidence implicating disturbances in the serotonin transporter and an array of psychiatric and physical illnesses, including fibromyalgia and irritable bowel syndrome. Disturbances in serotonin homeostasis as well inflammation-promoting (pro-inflammatory) cytokines have both been implicated as causative factors in major mental illness. So the hunt has been on to see if there’s some way of uniting these two causative pathways.
There’s an exceptional important paper out this week in the journal Neuropsychopharmacology.
Investigators from the Vanderbilt University School of Medicine in Nashville, Tennessee, have established that the pro-inflammatory cytokines interleukin-1beta and tumor necrosis factor-alpha activate serotonin transporters. Using rat cells, they were able to show the precise mechanism by which these cytokines could regulate the activity of the serotonin transporter.
So why is this so important? Not only does it open up several new options for treating mental illness, but it may also explain some puzzles.
It’s recently been shown that mental illness is more common in overweight people. Large amounts of fat in the abdomen act as a kind of inflammation factory, soaking the circulation in inflammatory mediators. So here we have a link between ever expanding waistlines and the increasing rates of mental illness in the population. It’s not just stress and environmental overload; it is likely also fat causing inflammation.