Brain Anatomy of Major Depressive Disorder

During major depressive disorder, the brain's structures in the cerebral cortex do not control the emotions evoked by overactive emotional centers. As the brain functions abnormally, hormonal supports for good mood stay at too low a level.

Hypofrontality

• In persons with major depressive disorder, the higher cortex that includes the prefrontal cortex activates less. When activity is less, the brain does not adequately control negative emotions, and attention and memory lessen.

Brain Tissue Loss

• A severe and recurrent experience with depression can lead to loss of brain tissue in the underactive regions. Frontal cortex areas can decrease in size.

Hyperactive Brain Emotional Centers

• Blood flow and activity increase in the amygdala, a center that controls pleasure. The thalamus enlarges markedly.

Serotonin Deficiency

• In the neuron synapses in the brain centers, one of the important neurochemicals that elevates mood, serotonin, decreases to levels as low as below half the normal level. The brain's systems that are stimulated by serotonin, which keep the mind at ease so the mind can rest and sleep, become less active.

Poor Regulation

• The brain poorly regulates the systems with norepinephrine neurons that control adrenaline levels.