Published on Wednesday, 30 November -0001 00:00
Could an injury to a particular part of the brain "cure" depression?
The answer, from a long-running study of Vietnam War veterans, seems to be a qualified yes.
Neuroscientist Michael Koenigs and colleagues recently published a paper in the Journal of Neuroscience, showing that damage to the ventromedial prefrontal cortex (VMPC) seems to protect against depression. Damage to that section, located behind the eyes, makes people less likely than the general population to suffer depression. Conversely, damage to the dorsal prefrontal cortex (DPFC) is correlated with an increased likelihood that the person will suffer from depression.
The findings bolster existing evidence about which portions of the brain may be targets for surgical and electrical interventions, says Koenigs, an assistant professor of psychiatry at the University of Wisconsin School of Medicine and Public Health.
"It may help us develop anatomically focused treatment strategies for depression,' he said. "Treatments could be aimed at selectively inhibiting or stimulating certain parts of the brain."
The subjects in the study come from the Vietnam Head Injury Study (VHIS), a registry of hundreds of Vietnam veterans who sustained penetrating brain injuries during combat. Koenigs said these veterans suffered injury, usually from shrapnel, to particular portions of the brain. Because of stronger head gear, these injuries are less common in Iraq veterans, who have tended to suffer concussive brain injuries.
In an earlier study on the veterans, done when he was at the National Institutes of Health, Koenigs and colleagues showed that injury to the VMPC (along with the the amygdala) was also linked to lower rates of post-traumatic stress disorder. Koenigs said this region of the cortex is involved with social emotions and self-insight, controlling such feelings as shame, guilt, embarassment and regret. Since these emotions play a role in both depression and PTSD, not being able to experience them may protect against the cognitive/affective symptoms of depression. (The injuries did not change somatic depression symptoms, such as changes in sleep and appetite.)
Koenigs and colleagues compared the Vietnam veterans to another group of pre-frontal cortex-damaged patients who were part of a long-running study at the University of Iowa. While the Iowa patients differed from the veterans' group in age, sex and how they were injured, the effects of their brain injuries were the same.
In probably the most stunning example, the paper cited one woman who suffered from severe depression and inadvertently cured herself when she attempted suicide by shooting herself in the head. The gunshot destroyed most of her VMPC. The patient's neuropsychologist, neurosurgeon and long-term boyfriend agreed that her depression symptoms mostly vanished after the injury. Her neuropyschologist noted "she never shows distress, worry or anger."
Of course, such damage is not a cure-all. Koenigs was also involved in another University of Iowa study that showed that people with VMPC damage also had impaired moral judgment.
For example, when given the choice of killing their own child to save money the VMPC patients made the same decision--not to kill the child--as did uninjured people. But if the scenario was to smother their own child to prevent harm to others, the VMPC patients would more often approve of killing the child The researchers concluded that a working VMPC is needed for judging right from wrong.
The study points to areas of the brain that could be selectively targeted for therapy. Either inhibiting the VMPC or stimulating the DLPC may alleviate depression, Koenigs concludes.