Pre-Kraepelinian observations converged in Kahlbaum's and Hecker's description of Hebephrenia. For Kraepelin, Hebephrenia was an 'idiopathic incurable dementia whose onset is in adolescence'. It became the core of 'Dementia Praecox', and then Bleulerian 'Schizophrenia'. In recent decades, the resurgence of the 'late neurodevelopment' hypothesis of schizophrenia has brought into focus Hecker's clinical reports of adolescents who, as a result of a putative loss of psychic energy, showed a rapidly progressive cognitive impairment leading to functional and behavioural disorganization. This paper summarizes the nineteenth-century conceptualization of Hebephrenia as a developmental illness.
Keywords: Dementia praecox; Hebephrenia; Hecker; Kahlbaum; Schizophrenia; neurodevelopment; pre-Kraepelinan psychiatry.