A certain type of brain cell may be linked with suicide, according to a recent investigation. People who take their own lives have more densely packed von Economo neurons, large spindle-shaped cells that have dramatically increased in density over the course of human evolution.

Researchers in Germany analyzed the roots of suicide in the brain by focusing on a neural network linked with psychological pain, which includes regions such as the anterior cingulate cortex and the anterior insula, where von Economo neurons are concentrated. These cells bear receptors for neuro­transmitters that help to regulate emotion, such as dopamine, serotonin and vasopressin. Because they are found in highly gregarious animals such as whales, elephants and apes—with humans possessing the highest densities—scientists believe they might specifically deal with complex social emotions such as shame.

The team compared the density of von Economo neurons in nine patients who died from suicide and 30 who died of natural causes, such as heart failure. All subjects had been diagnosed clinically with either schizophrenia or bipolar disorder. The researchers found the density of these neurons was significantly greater in those who died of suicide than in those who had not, regardless of what disorder they had. Evolutionary psychiatrist and neuroscientist Martin Brüne of University Hospital Bochum and his colleagues detailed these findings online June 22 in PLoS ONE.

If von Economo neurons do play a role in processing complex emotions such as empathy, guilt and shame, an overabundance may in some cases trigger emotional disturbances, potentially explaining the link seen with suicidal behavior, Brüne says. He adds that high densities of von Economo neurons do not necessarily cause suicide: “Having good empathetic abilities is certainly something that is advantageous in most situations but perhaps can have deleterious effects under very specific circumstances.” Future insights into the role of these cells in emotion and cognition might lead to ways of addressing suicidal tendencies, he says.

*Correction (11/1/11): The image in this story was changed after posting because the original did not display von Economo neurons.