His son Jules Falret (1824-1902), with psychiatrist Ernest-Charles Lasègue (1816–1883), identified a shared psychotic disorder sometimes referred to as "Lasègue-Falret syndrome" ("folie à deux"). The syndrome is characterized by the coincidental appearance of psychotic symptoms in family members while living together, as well as retention of the symptoms when the individuals are separated. This syndrome can also involve a situation where a diseased family member transmits psychotic symptoms to healthy members of the family. The two doctors published their findings in a treatise called "La folie à deux ou folie communiquée".