How does major depression affect the body?

Neurotransmitters, such as serotonin, are chemicals that send information to the brain and are responsible for mood. If the brain does not receive the information correctly from the neurotransmitters, the result may be major depression. Because neurotransmitters help control mood, these changes can cause you to feel sad for an extended time. Many of the medical treatments available for clinical depression regulate the levels of neurotransmitters in the brain in order to stabilize mood.