Recent research suggests that social anhedonia may represent a prodrome of psychotic disorders. These syndromes may or may not be preceded by a prodrome. Describing the schizophrenia prodrome has been useful in promoting early intervention. An antecedent viral prodrome occurs in approximately one-third of cases. Each episode is divided into four phases&colon; inter-episodic, prodrome, vomiting, and recovery. Roughly 30% of patients have experienced an associated viral prodrome. Some reports point to a prodrome of several years for RRMS and decades for PPMS. Heart related causes also often have little history of a prodrome.