I.) Decreased production of neurotransmitters due to:

• A deficiency of NT precursors (not enough “raw materials” in the body to correctly manufacture NT’s)
• Inborn errors of metabolism (an individual may have a genetic need for more of the “raw materials” used to build neurotransmitters)
• Toxic damage to portions of the brain or peripheral nervous system that produce NT’s

II.) Increased need for neurotransmitters due to:

• Toxic damage to or destruction of the nerve cells the respond to NT input
• Excess degradation of existing NeuroTransmitters due to reuptake inhibiting drugs or recreational drugs