In my initial post in 2018, a 2024 post, and a recent post, I faulted psychiatry for continuing its pursuit of brain diseases as causes for mental disorders when they have not found any in this century. But, in fairness, there’s a good reason for expecting a disease to cause mental disorders.
The Origin of Clinical Medicine’s Focus on Physical Disease
In the 17th century, Descartes’s mind-body split theory established medicine’s primary interest in the physical…
In my initial post in 2018, a 2024 post, and a recent post, I faulted psychiatry for continuing its pursuit of brain diseases as causes for mental disorders when they have not found any in this century. But, in fairness, there’s a good reason for expecting a disease to cause mental disorders.
The Origin of Clinical Medicine’s Focus on Physical Disease
In the 17th century, Descartes’s mind-body split theory established medicine’s primary interest in the physical body, which would later extend to its physical diseases. It also shunted aside the mind so that psychological and social issues and mental illnesses would be peripheral in medicine. But the theory had little initial impact on clinical care. Clinicians would continue to be guided by the ancient theory that explained disease as an imbalance of the four humors, which bloodletting could rebalance, until the 20th century.
But the first chink in the armor of the four humors idea came in the 18th century. Autopsies played the key role in replacing imbalances of the four humors as a disease explanation. Giovanni Battista Morgagni (1682–1771) launched this revolution1 by conducting 700 autopsies that he correlated with patients’ symptoms (obtained from clinical records).2,3 He recognized that the abnormal appearances of different body organs correlated with different symptoms, for example, cough and chest pain where the autopsy showed fluid and consolidation in a lung, or abdominal pain and vomiting where the autopsy showed growths in the stomach and an enlarged, bloody liver. Clinicians recognized, for the first time, that the abnormal appearing organs observed at autopsy represented disease and caused patients’ symptoms and death. This linkage of abnormal (diseased) organs to the patient’s symptoms was called clinical-pathological correlation (CPC) and would become the representation of the mind-body split in modern clinical medicine.
But medicine at this early point had not identified actual causes of any diseases, only that the organs were abnormal. Today’s more advanced knowledge and expertise would be required to make diagnoses like tuberculosis or cancer. At the end of the century, Francois Bichat (1771–1802) found that body organs consisted of many different tissues such as arteries, muscle, mucous membrane linings, and nerves. He then showed that an organ’s disease was restricted to its tissues rather than involving the whole organ, for example, the disease was in the arteries of the heart but not its muscle or membranous lining.1 While Rudolf Virchow (1821–1902) later established the cellular basis of disease,4 CPC had already been firmly established.
Philosopher Michel Foucault (1926–1984) insightfully articulated the first patient care implications of CPC.5* *The physician’s “gaze” changed. They no longer took an interest in the patient’s personal and social life. Rather, they restricted their interests to physical symptoms that might point to an abnormal organ or tissue in the body, that is, a disease. This is the provenance of what we unhappily often observe in today’s clinicians, ignoring our personal issues to focus on a physical symptom. And, understandably, doctors began to place more interest on the physical examination, for example, valuing palpation of an enlarged liver or hearing a heart murmur over the patient’s personal concerns. The patient simply became a mystery to solve. The die was cast for a modern medicine that would be impersonal but successful in controlling diseases.
The mind-body split and CPC would not come to full implementation by practitioners until the 20th century. Its successes came when it was complemented by the disease-oriented drug (penicillin, beta blockers, statins, GLP-1 agonists) and technological (MRI, genetics, AI) advances. These led to, for example, heart and kidney transplants, the cure of AIDS, the eradication of polio and smallpox, cures in cancer, and, most impressively, the doubling of life expectancy from 40 years to 80 years.
Psychiatry Embraces Physical Diseases
Although psychosocial and mental health issues faded out of sight for most of medicine, a small cadre of physicians, budding psychiatrists, took up the cause of mental illness in the 1800s. Picking up on successes in physical disease medicine, it was logical to conclude that brain diseases caused psychiatric symptoms and disorders. And they found an encouraging model in the autopsy changes in the brains of patients with neurosyphilis. But their many later efforts failed to find a brain disease in patients with what they then called melancholia, mania, idiocy, and dementia. Nor has an explanatory disease been found subsequently.
After flirting with patients’ more human psychological and social issues during the Freudian era early in the last century, psychiatry more fully embraced disease causation as advances in techniques to study the brain and genetics emerged. And the successes of lithium (with bipolar disorder) and chlorpromazine (with schizophrenia) suggested a chemical disease of the brain and led to a preferential interest in drug management that persists to this day.
Although modern psychiatry may appear stuck in still seeking a disease cause for mental illnesses, there is hope on the horizon for a new understanding. We’re hearing of evolutionary explanations that shun disease causation and favor the idea of adaptive or maladaptive responses to life stresses. And experts advise new ways to classify psychiatry that don’t entail disease explanations, and there’s a new focus on brain mechanisms (not diseases) for mental illnesses that reflect the brain’s role as an information-processing organ.
Psychiatry Essential Reads
While it’s time to change gears, it’s also understandable why a disease interest is so pervasive when we realize it’s been four centuries in the making and has worked for physical diseases.
Adapted from *Has Medicine Lost Its Mind?*6(Prometheus Books, 2025).
References
1. Nuland S. Doctors: The Biography of Medicine. Vintage Books, 1988.
2. Garrison F. An Introduction to the History of Medicine, With Medical Chronology, Suggestions for Study and Bibliographic Data. WB Saunders Company, 1929.
3. Porter R. The Greatest Benefit to Mankind: A Medical History of Humanity. W. W. Norton and Company, 2009.
4. Mukherjee S. The Song of the Cell: An Exploration of Medicine and the New Human. Scribner, 2022.
5. Foucault M. The Birth of the Clinic: An Archeology of Medical Perception (English translation).
6. Smith R. Has Medicine Lost Its Mind? Why Our Mental Health System Is Failing Us and What Should Be Done to Cure It. Prometheus Books (an imprint of The Globe Pequot Publishing Group, Inc.), 2025.