Karl Grassmann's 1896 paper “critical overview of contemporary theories of the heredity of the psychoses”

Abstract

Four years before the rediscovery of Mendel's work in 1900, Karl Grassmann published a detailed, scholarly review of the heredity of psychosis which we here review.A full translation is in the appendix. We emphasize seven major conclusions from this review. First, while recognizing the key importance of heredity in the etiology of psychosis. Grassmann was critical of many of the highly speculative extant theories. Second, he reviewed most of the major methodologic concerns in the literature from what kinds of heredity to investigate to the problems with the global use of insanity as a diagnostic category. Third, he discussed in detail genetic theories associated with Degeneration theory, maintaining considerable skepticism. Fourth, he recognized nongenetic contribution to familial transmission. Fifth, he reviewed evidence for both homogeneous and heterogeneous transmission of forms of mental illness in families, suggesting that both were important. Sixth, while he noted that mania, melancholia, and cyclothymia commonly replaced each other in families, Verrücktheit (delusional psychoses) rarely co-segregated in families with these mood disorders. Seventh, Grassmann, like other 19th century writers, saw relatives to be of value only in assessing the level of hereditary predisposition in patients and had limited appreciation of the need for controlled studies.

William Boven's 1915 thesis “Similarity and Mendelism in the heredity of dementia praecox and manic‐depressive insanity”

“…In prior papers, we have reviewed four key articles from this period. The first was a brief summary of a thesis by Ryssia Wolfsohn published in 1907 under the direction of E. Bleuler which used the concept of “hereditary burden” similar to 19th‐century asylum‐based studies but performed them, for the first time to our knowledge, to cases diagnosed at the Burghölzli hospital in Zurich as DP (Kendler & Klee, 2023b). The second was published in 1911 by Ernst Rüdin—a central figure in much of this work—and contained his vision for a highly ambitious, Mendelian‐based research program in psychiatric genetics (Kendler, 2021a).…”