A “chemical imbalance involving neurotransmitters” has become a common way of describing the underlying biology of depression and anxiety. However, neurotransmitters are just one part of a vast process of functions and structures that play a role in mood disorders.
Serotonin, norepinephrine, and dopamine are the primary neurotransmitters that play some role in MDD. They are chemical messengers that transmit signals in the brain and play crucial roles in regulating mood, emotion, motivation, sleep, and many other functions.