It's Fair To Describe Schizophrenia As Probably Mostly Genetic
Feb 9, 2024
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Schizophrenia researcher E. Fuller Torrey and philosopher Awais Aftab discuss the genetic origins of schizophrenia. They question whether schizophrenia should be categorized as 'mostly genetic' and explore biases in twin studies and the interpretation of heritability numbers. They also explore the role of genetic and environmental factors in schizophrenia and debunk the misconception that genetic causes are less desirable. The podcast concludes by discussing different perspectives on classifying schizophrenia as an autoimmune, viral, or genetic disease.
Schizophrenia should not be solely labeled as a genetic disease, even if studies show it to be 80% heritable.
Acknowledging the primarily genetic nature of schizophrenia can be a meaningful approach amidst its complex and multifactorial causes.
Deep dives
Schizophrenia is primarily genetic
The podcast discusses the arguments surrounding the heritability and genetic factors of schizophrenia. It explores the views of E. Fuller Tory, a famous schizophrenia researcher, who questions the dominant narrative that schizophrenia is mainly genetic. However, the podcast presents a counterargument by Oaius Aftab, who suggests that even if the studies show schizophrenia to be 80% heritable, it should not be solely labeled as a genetic disease. Nevertheless, the podcast asserts that given the various possible causes of schizophrenia and the prevalence of genetic factors, it is reasonable to consider schizophrenia as primarily genetic.
Genes as risk factors and causes
The podcast examines the distinction between risk factors and causes in the context of smoking and lung cancer. It questions whether this distinction is applicable to schizophrenia and its genetic factors. While some argue that genes are merely risk factors, the podcast highlights that smoking is considered both a risk factor and a cause of lung cancer. Similarly, the podcast suggests that genetic factors should be recognized as causing schizophrenia, even though they may also contribute to other conditions. The analogy drawn is that just as smoking is colloquially seen as the main cause of lung cancer, genetics can be acknowledged as playing a significant role in schizophrenia.
The multifactorial nature of schizophrenia
The podcast explores the multifactorial nature of schizophrenia, emphasizing that it is a complex condition with various possible causes. It draws an analogy with kidney disease, explaining how kidney disease can result from different causes, and the term 'kidney disease' serves as a catch-all term for any factor negatively impacting kidney function. Similarly, the podcast proposes that schizophrenia may be conceptualized as cumulative damage to a computational system in the brain, caused by a combination of genetic and environmental factors. Although specific causal processes are yet to be fully understood, the podcast suggests that acknowledging the predominantly genetic nature of schizophrenia can be a meaningful approach in the absence of a singular, more satisfying cause.
Famous schizophrenia researcher E. Fuller Torrey recently wrote a paper trying to cast doubt on whether schizophrenia is really genetic. His exact argument is complicated, but I feel like it sort of equivocates between “the studies showing that schizophrenia are genetic are wrong” and “the studies are right, but in a philosophical sense we shouldn’t describe it as ‘mostly genetic’”.
Awais Aftab makes a clearer version of the philosophical argument. He’s not especially interested in debating the studies. But he says that even if the studies are right and schizophrenia is 80% heritable, we shouldn’t call it a genetic disease. He says:
Heritability is “biologically vacuous” (Matthews & Turkheimer, 2022), and I think we would be better off if more of us hesitated to assert that schizophrenia is a “genetic disorder” based predominantly on heritability estimates.
I think about questions like these through the lens of avoiding isolated demands for rigor. There are always complicated ways that any statement is false. So the question is never whether a statement is perfectly true in every sense. It’s what happens when we treat it fairly, using the same normal criteria we use for everything else.