Neurotransmitters

• According to the Mayo Clinic, depression has been treated successfully by increasing low levels of certain neurotransmitters with antidepressant medication.
  
  

Hippocampus

• According to the National Academy of Sciences, there is a nearly 20-percent reduction in the volume of the hippocampus, a region of the brain controlling memory and learning, in individuals affected by depression.
  
  

Pineal Gland

• The University of Maryland Medical Center reports depressed individuals do not produce adequate amounts of melatonin, a neurotransmitter produced by the pineal gland.
  
  

Thalamus

• Depression sufferers possess roughly 30 percent more neurons in the thalamus, an area of the brain controlling fear and other emotions, according to the U.S. Department of Veterans Affairs.
  
  

Cerebral Cortex

• Depressed individuals exhibit thinning of the right-side cerebral cortex, influencing mood, attention, and more, according to a report by the New York Times.