Ludvig Dahl's psychiatric genetic studies in his 1859 monograph: “Contribution to the knowledge of insanity in Norway”

Abstract

In 1859, Ludvig Dahl, a Norwegian alienist, wrote a rarely referenced book entitled "Contribution to The Knowledge of Insanity." In it, he describes a highly innovative psychiatric genetics research project with severable notable features. First, while the vast majority of 19th century psychiatric genetic studies were based on asylum hospital records, Dahl did field work to find cases of mental illness in certain defined areas within Norway, using census data, key-informants, record reviews, and personal interviews especially of suspected affected individuals. Second, for the first time in the history of psychiatric genetics, and perhaps more broadly in medical genetics, Dahl studied and graphed extensive pedigrees covering up to seven generations demonstrating a high density of psychiatric illness. Third, he proposed and conducted the first controlled investigation of familial aggregation of insanity. A 126 member 5-generation pedigree that he studied contained 8 individuals with confirmed insanity compared to 16 cases in the remaining 2,974 individuals in the Parish, a relative risk of nearly 12. Dahl also noted the co-segregation within pedigrees of mental handicap, deaf-mutism, and insanity. He evaluated familial-environmental sources of familial aggregation and noted, among nonpsychotic family members in his pedigrees, personalities that might reflect a "disposition" to insanity. | INTRODUCTIONThis essay provides a detailed description of the contributions to the history of Psychiatric Genetics of Ludvig Dahl contained in his 1859 book entitled "Bidrag Til Kundskab om De SindssygeINorge" [Contribution to The Knowledge of the Insane in Norway] (Dahl, 1859) accompanied by the first English translation of the relevant text in an AppendixS1. This article is divided into four parts. First, we provide, the historical context of Dahl's work with respect to the general development of Psychiatry and particularly that of the very young science of psychiatric genetics. Second, we give a brief biography of Dahl. Third, we review the sections of his book dealing with his findings in the genetics of insanity. Finally, we review the prior material, seeking to place Dahl within the broader history of the field of psychiatric genetics.2 | HISTORICAL CONTEXT Nineteen years before the publication of Dahls' monograph, the pupil of Pinel (1745-1826) and the last great figure in early 19th century French Psychiatry, Jean-Etienne Dominique Esquirol (1772-1840), died. Five years earlier in 1854, the French alienist Falret published an article describing a syndrome that would evolve into what we now term bipolar disorder (Sedler, 1983). Three years earlier, in 1856, Emil Kraepelin (1856-1926), to be the dominant figure in late 19th and early 20th century European psychiatry, was born. In the same year as Dahl's publication, in 1859, the first edition of the most influential psychiatric textbook in mid-19th century Britain "A Manual of Psychological Medicine" by John Bucknill (1817-1897) and Daniel Tuke (1827-1895) was published (Buc...

The examination of Kraepelin's diagnoses of dementia praecox and manic‐depressive insanity in pedigrees: Studies of Schuppius in 1912 and Wittermann in 1913

“…First, these papers instantiated a major methodological shift in psychiatric genetics. Most psychiatric genetic studies of the 19th century, with some important exceptions (e.g., Dahl, 1859; Kendler et al, 2022) and by Doutrebente (1869), focused on aggregate hereditary burden and did not report the disease status of individual relatives at a particular place in the pedigree. This point is best demonstrated by a paper published by Wolfsohn in 1907, only 5 years prior to the report by Schuppius, which studied genetic risk for Kraepelin's new diagnostic category of DP but used aggregate measures of hereditary burden and did not, in the entire detailed report, consider individual relatives or pedigrees (Wolfsohn, 1907).…”

“…Unlike the approach advocated by the Rüdin school of focusing on one class of relatives at a time, these investigators, working in clinical positions and lacking the resources of a research institute, studied pedigrees of probands ascertained through the asylums at which they worked. The first study of large pedigrees focusing on psychiatric illness was performed in rural Norway by Ludvig Dahl in 1859 (Dahl, 1859; Kendler et al, 2022), followed by Doutrebente in France in 1869 (Doutrebente, 1869). As outlined by Gausemeier (2015), pedigree studies became particularly popular at the end of the 19th century in Germany, in part as a result of the publication of Ottokar Lorenz's “Handbook of Scientific Genealogy” in 1898 (Lorenz, 1898).…”