Did you know that powerful magnetic pulses applied to the scalp can bring fast relief to severely depressed patients for whom standard treatments have failed?
This treatment is known as Transcranial magnetic stimulation (TMS).
Although TMS works, no one knew how it changes the brain to alleviate depression — until now.
A new study by Stanford Medicine scientists discovered that TMS works simply because of how depression affects the brain.
How does depression affect the brain? Depression and brain changes
Depression affects the brain by reversing how brain signals are sent. In healthy people, the anterior insular sends brain signals to the anterior cingulate cortex. But in depressed individuals, brain signals are sent from the anterior cingulate cortex to the anterior insular.
These brain changes caused by depression is why depressed individuals no longer enjoy activities that once brought them excitement.
That's because the anterior cingulate cortex governs emotions. When this region receives brain signals, it responds according to the stimuli. That is, you feel happy when you receive positive signals.
But when this same region governing emotions becomes the one sending out signals, the mood you're already experiencing (depression) overshadows everything else.
But here's the good news.
TMS alleviates depression by reversing the direction of brain signals back to normal.
More brain changes, more severe depression
The researchers noticed that the more signals traveling the wrong way, the more severe the depression. This indicates that where brain signals are sent and received plays a significant role in depression.
Also, people with more severe depression and misdirected brain signals are more likely to benefit from the TMS treatment.
Until now, the biological mechanisms involved in depression have been a mystery.
When someone has a fever, a blood test can reveal what's wrong at the biological level, letting us know what medication to give them. But it's different with depression because we don't know exactly what's going on.
Thankfully, this breakthrough research brings us closer to understanding depression on a biological level. The researchers believe that the abnormal flow of neural activity between brain regions could serve as a biomarker for depression.
This biomarker may help determine which patients are likely to respond well to TMS treatment, leading to more personalized and effective depression interventions.
Read the full research here.