How Can Neurotransmitters Negatively Affect Psychological Functioning

How can neurotransmitters negatively affect psychological functioning?

A) when they are chemically transformed and not recognizable by the brain
B) when the wrong neurotransmitters come in contact with a neuron
C) when production of neurotransmitters is either excessive or insufficient
D) when an individual produces antibodies that make neurotransmitters ineffective