The Physiology of Depression

The physiology of mood disorders is complicated, and not particularly well understood. What we do know comes from brain imaging and looking at the levels of different chemicals in the brain. There may be some long, confusing words you've never heard of here, but stick with it, because what this stuff tells us is important.

In unipolar depression, the physical problem is believed to be an imbalance of either serotonin, noradrenaline or dopamine in the brain; or two or all three of those. Exactly how we don't know, and the exact imbalance is probably different for everybody, but generally speaking, most people with depression have less serotonin, or noradrenaline in their brain than healthy people do. The pathophysiology of Bipolar Disorder is poorly understood, but it is probably linked to the same three neurotransmitters as well as some structural abnormalities in the amygdala, basal ganglia and prefrontal cortex.1

PET (Positron Emission Topography) and SPECT (Single Proton Emission Computed Topography) scans are two types of brain scans which show how active or inactive the different areas of the brain are. PET scans of depressed brains compared to normal ones show a significant reduction in overall brain activity. This is why everything seems ten times harder when you're depressed and why it's much harder to concentrate and remember things. People with depression are like cars running on half a tank of gas, or in some cases hardly any gas at all. You can barely get out of the driveway, let alone make it around the block. In other words, if you're depressed, you can't expect yourself to carry on with your normal life while you are ill. So give yourself a break!

In people with Bipolar Disorder, PET and SPECT imaging usually shows decreased activity in the prefrontal cortex, which is involved in emotion and planning, the amygdala, which is associated with mood regulation, and the hippocampus2. This may explain the intense highs and lows bipolar sufferers experience. Patients in the depressed phased of a cycle show very similar scan results to patients with unipolar depression. In the manic phase, imaging shows both left-right and dorso-ventral asymmetry in the basal temporal cortex. I have absolutely no idea what that means.

But whether you have any idea of what a basal temporal cortex is or not, the important thing to understand is that...

[in serious mental illness] Your brain is physically injured, and like any other part of the body that has received a physical injury, it needs the proper care to heal... The problem that far too many people have is that they can't see the injury, therefore it is not a real injury... - Jerod Poore, Crazy Meds 3

Whether you suffer from a mood disorder or not, you should know that they are genuine medical conditions with physical manifestations in the brain. Just because you can't see the physical problem, it doesn't mean that it's not there. If you could have one of those fancy brain scans yourself, you would see it. Use this information to accept the fact that you're ill, and you need rest and medical treatment. You're not weak or selfish or any of the other things people may accuse you of. You're not well. Got it? Good.

Sources:
1. Internet Mental Health
2. Rachel Pollock, PhD & Irving Kuo, MD - "Neuroimaging in Bipolar Disorder"
3. Jerod Poore, Crazy Meds
4. Karl Hempel, MD - "Depression: What You Need To Know"
5. Amen Clinics SPECT Imaging