Deep Brain Stimulation Depression

Deep Brain Stimulation (DBS) involves implanting an small electrode like device into specific areas of the brain. The electrode sends controlled jolts of electricity to the brain and this can improve symptoms for a myriad number of disorders. The area of the brain with the best evidence for mood enhancement using a DBS device is Broadman Area 25. This area of the brain is located in a band that runs deep within the frontal lobes, down the midline. In healthy patients, feelings of profound sadness are associated with increased activation of this brain area. In depression this area shows increased blood flow in comparison to a person without depression and the area is activated for a longer period than in a healthy person. In one such study, 4 out of 6 depressed patients had a striking improvement in their symptoms when the DBS device was implanted in this specific area of the brain. The DBS device can reduce overactivity in that area. So stimulation of this area with a DBS device improves the crushing and despondent sadness that is often associated with major depression.

Currently, scientists are testing in clinical trials an implant device that sends electricity to the medial prefrontal cortex. The medial prefrontal cortex is located behind the bridge of your nose and is important for proper emotional functioning. This area of the brain is involved in attention, interest, emotion and also empathy. A deficit of activity here could concievably cause apathy, poor attention and emotional blunting. So targeted electrical stimulation of this area could lead to an overall improvement in a person's mood. In the future, it may be possible to amplify the experience of empathy so people are more empathatic and warm to each other using a DBS type device. Deficits in empathy are common in several disorders such as autism, asperger's, schizophrenia, anti-social/narcissistic personality disorders and sometimes depression. So a DBS device in this area of the brain might be able to improve those deficits in normal functioning. Interestingly, direct electrical stimulation of the medial prefrontal cortex is rewarding. This is another hedonic hotspot in the brain in comparison to the more well known brain region related to reward (the nucleus accumbens).

The nucleus accumbens has usually been considered the main reward related region in the brain and has been targeted by researchers. DBS devices have been implanted directly within this area of the brain. The nucleus accumbens is mostly involved with feelings of experienced pleasure and doesn't necessarily have a direct effect on many other symptoms of depression such as sad mood. Researchers have found that implanting a DBS device in this area of the brain alleviated refractory anhedonia. However, the other core symptoms of depression such as sad mood we're not changed significantly. DBS devices have been shown to induce euphoria when implanted in this area. So care must be taken by researchers so as not to make person too happy.

Several other areas of the brain have potential antidepressant properties. Scientists have reported on improved mood following a DBS device being implanted into the globus pallidus. The device was actually implanted to treat the movement disorder tardive dyskinesia, but the patient's depression also improved quite a bit. Stimulating the lateral habenula may also have antidepressant properties. Increased activation of the lateral habenular nucleus leads to the down regulation of the serotonergic, noradrenergic, dopaminergic systems and overactivty of the hypothalamic-pituitary-adrenal (HPA) axis. So decreasing activity in this area can decrease the stress response and increase several different mood improving neurotransmitters. Another group of scientists implanted a DBS device into the inferior thalamic peduncle. The researchers found that it had a good effect on the person's depression and that their mood improved progressively over an eight month period. The results for some of these areas are only preliminary. More rigorous clinical trials are needed to discern the true clinical benefit of doing this procedure. However, it could potentially improve the quality of many people's lives in the future.