Could Depression be caused by an Infection?

By U.S. Navy photo by Lt. Cmdr. Mike Morley [Public domain], via Wikimedia Commons

Around 1907, the time well before modern, randomized clinical research trials, American psychiatrist Henry Cotton started removing rotten teeth from his patients, in the hopes of curing whatever mental health disorder the person had. If that didn’t help, Dr. Cotton went on to more invasive excision of such organs as the ovaries, testicles, tonsils and in some situations, the colon.

Dr. Henry Cotton

Dr. Cotton was the newly appointed director of the New Jersey State Hospital for the Insane. He was acting on a proposed theory by Johns Hopkins psychiatrist Dr. Adolf Meyer, who Cotton had studied under.

Dr. Meyer believed that psychiatric illnesses were the result of a chronic infection. His ideas was founded on observations that patients with high fevers sometimes became delusional and hallucinated.
Cotton latched onto the idea and started to do removals and extractions of his own.

In 1921, Dr. Cotton published a book entitled “The Defective Delinquent and Insane: the Relation of Focal Infections to their Causation, Treatment and Prevention.” The book was publicly well-received.

A few years later, the New York Times wrote, “eminent physicians and surgeons testified that the New Jersey State Hospital for the Insane was the most progressive institution in the world for the care of the insane, and that the newer method of treating the insane by the removal of focal infection placed the institution in a unique position with respect to hospitals for the mentally ill.”

Dr. Cotton passed away in 1933 and interests in his methods and cures faded. The mortality rates of what Dr. Cotton did were around 45 percent and in all likelihood his treatments didn’t work. However, though his rogue tactics were probably misguided, there may be something to his thoughts of infection and inflammation being involved with mental illness.

The Symptoms of Mental Illness and Depression Can Overlap

In late 2014, Dr. Turhan Canli, an associate professor of psychology and radiology at Stony Brook University, published a research paper in the journal of Biology of Mood and Anxiety Disorders. His paper asserts that depression should be viewed as an infectious disease.

Dr. Canli stated, “Depressed patients act physically sick. They’re tired, they lose their appetite, they don’t want to get out of bed.” He notes that while Western medical practitioners like to focus on the psychological symptoms of depression, in many non-Western cultures, people who would receive a depression diagnosis report primarily physical symptoms, partially because of depression being so stigmatized.

Dr. Canli further stated, “The idea that depression is caused simply by changes in serotonin is not panning out. We need to think about other possible causes and treatments for psychiatric disorders.”


The concept of a relationship between depression and the immune system is nothing new. In the 1930s, autoantibodies were first reported in patients with schizophrenia. Subsequent research studies have detected antibodies to various neurotransmitter receptors in the brains of psychiatric patients.

In spite of all the study that’s been done, researchers have found associations, but this does not prove a cause and effect relationship between inflammation and mental health issues.


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