A case of "pfropfschizophrenia": Kraepelin's bridge between neurodegenerative and neurodevelopmental conceptions of schizophrenia.

Abstract

The notion that schizophrenia, as conceived by Kraepelin, is a neurodegenerative disorder has been challenged by new research on the nature of the cognitive impairment in this disease; instead, schizophrenia is increasingly described as a neurodevelopmental disorder (1). For Kraepelin, the unifying observation among the catatonic, hebephrenic, and paranoid types of dementia praecox was a continued decline of intellectual function. However, empirical findings have demonstrated that cognitive function does not universally decline in patients with schizophrenia. Some authors have suggested that low intellectual functioning is a premorbid and fixed feature (2). Others have sought to separate patients according to different “trajectories” of lifetime intellectual function that include subsets of schizophrenic patients with intellectual functioning that was either compromised from a very early age or preserved at normal premorbid levels (3, 4). Finally, there have been attempts to determine if there are differences in change among cognitive functions (intellect, memory, executive, and attention) in schizophrenia (3). These data seem to be mutually exclusive of some of Kraepelin’s most important observations, and they generally support the “static encephalopathy” concept that asserts that schizophrenia is due to a stable neurodevelopmental brain lesion (5). The increasing dominance of the neurodevelopmental paradigm is illustrated by the American Academy of Child and Adolescent Psychiatry’s declaration that “schizophrenia is a neurodevelopmental disorder” (6) and also by Prusiner’s exclusion of schizophrenia (7) from the neurodegenerative disorders, all of which, in his perspective, “result from abnormalities in the processing of proteins.” One wonders whether this dichotomous landscape has room for only one perspective at a time. However, neurodegeneration was not so monolithic in Kraepelinian thought. In fact, Kraepelin did recognize and appreciate cases in which low intellectual functioning existed long before the onset of psychotic thought and did not worsen with the onset of the psychosis. That is, Kraepelin described a type of schizophrenia that resulted from a disruption in neurodevelopment. Kraepelin’s “Pfropfschizophrenie” referred to the 3.5% (8) to 7.0% (9) of cases of dementia praecox that were “engrafted” (pfropf, “to engraft” in German) upon, or the result of, “imbecility” during development. (The antique terms “imbecility” and “feeblemindedness” refer to mild and moderate mental retardation; “idiocy” refers to severe and profound mental retardation.) This concept was a recurrent idea in Kraepelin’s textbooks and should not be seen as a historical anomaly. It was an active piece of his view of dementia praecox and was recognized and discussed by Bleuler and others in the field for many years. This diagnostic entity is important because it suggests that at some level Kraepelin accepted a model of schizophrenia that was not simply neurodegenerative. His observations of pfropfschizophrenics, in fact, may be compatible with the ideas of the neurodevelopmental model. Of more importance, the modern reification of the concept of many schizophrenias, rather than just one, might rely on the demonstration of variations in cognitive impairment that reflect one of these paradigms and not the other. We suggest that this dichotomous relationship allows for coexistence, as Kraepelin did, and we propose that future study of this group in this manner would benefit both psychopathology as well as the clinical status of this vulnerable population. In this article, we present a case of a patient who might have been diagnosed with pfropfschizophrenia. His case provides compelling evidence for the diagnosis of both mental retardation and schizophrenia. With the benefit of formal neuropsychological testing performed while the patient was both in the preand postmorbid states, as well as some prenatal and childhood medical records, we review the difficult differential diagnosis of the case, the current literature on the relationship between intelligence and psychopathology, and the history of pfropfschizophrenia and its importance both to this case and to current thought about schizophrenia.