Most drugs that alter mental function, whether for recreational purposes or to treat mental disorders, affect synaptic transmission. Some drugs reshape the action potential, altering release of neurotransmitter; others antagonize or enhance the effect of a neurotransmitter on its synaptic receptor protein. Still other drugs inhibit reuptake of the neurotransmitter from the extracellular space, thus prolonging its action at the synapse. This leads naturally to the idea that disorders of thought, attention, and mood are fundamentally disorders of the synapse. Moreover, it presents a rationale for treating mental disorders by pharmacotherapy of the synapse.
Sterling P. Homeostasis vs AllostasisImplications for Brain Function and Mental Disorders. JAMA Psychiatry. 2014;71(10):1192-1193. doi:10.1001/jamapsychiatry.2014.1043