- Research Applied to Clinical Practice by Robert C. Knies, RN MSN CEN Section Editor SSRIs and Discontinuation Events Depression has been described as, a disease state characterized by complex alterations in several CNS neurotransmitters and receptor systems (Leonard, 1992). Part of the treatment involves antidepressant drugs that are known to cause adaptive changes in several CNS receptor ...enw.org/Research-SSRI.htm