Torrey & Miller: Our goal was to make readers aware that severe psychiatric illnesses, such as schizophrenia and manic-depressive illness, are comparatively recent diseases, less than 250 years old. By understanding this, we may also better understand historical events such as the Salem witch trials, the eugenics movement, and restrictions on immigration, as well as books such as Dracula and Dr. Jekyll and Mr. Hyde. We may also better understand why so many psychiatrically disordered individuals are now filling our streets, public parks, and jails.

Q: Why do you call the epidemic “invisible”?

Torrey & Miller: The epidemic is invisible because it came about over many decades and virtually nobody has noticed it. It is like a river that has risen very, very slowly.

Q: When did you first become interested in the topic and why?

Torrey:  In 1959, as a college student, I had a job delivering frozen foods to state psychiatric hospitals in New York State. At that time, Rockland State Hospital had over 9,000 patients and Pilgrim State had over 16,000. It appeared to me that some kind of epidemic had occurred; the psychiatric hospitals reminded me of the tuberculosis sanitariums of a slightly earlier era.

Q: Why did you decide to write this book?

Torrey:  In 1972, I submitted a paper on this topic for publication, but it was rejected. Since then, the visibility of psychiatrically ill individuals has markedly increased as hospitals have been emptied and patients have ended up homeless on the streets. It thus seemed like a good time to again try to raise awareness of this issue.

Q: Why did you choose 1750 as the starting point of your research?

Torrey & Miller: We chose 1750 because that was around the time when Samuel Johnson and a few other Englishmen first claimed that insanity was increasing. We believe that was the beginning of the epidemic.

Q: What do you mean by “insanity” and why do you use the term?

Torrey & Miller: “Insanity” was commonly used for three centuries to refer to individuals with brain diseases, including those we now diagnose as having schizophrenia, manic-depressive illness (bipolar disorder), and severe depression. It is thus a useful term and reflects the era about which we are writing.

Q: Throughout the book, you cite examples of insanity as it was reflected in literature. Why did you include such analyses?

Torrey & Miller: Literature provides an insight into the concerns of each era. Thus, when writers such as Dickens, Poe, Melville, and Hawthorne focused their stories on insanity, it was primarily because their reading public was intrigued by the subject. There was, in fact, widespread concern about rising insanity in the nineteenth century.

Q: Your examination of Lewis Carroll's “The Hunting of the Snark” is especially interesting. Can you briefly describe your thoughts on that work?

Torrey & Miller: The meaning of this poem has been one of the greatest mysteries in English literature. We believe that Carroll was writing about insanity and the death of his beloved uncle, who was killed by an insane man. 

Q: Why do you think so many famous writers were either personally affected by mental illness or fascinated by it?

Torrey & Miller: We note in the book that many writers had episodes of insanity, including William Collins, Christopher Smart, William Cowper, Charles Lamb, John Clare, and Virginia Woolf. One reason for this is simply that insanity was becoming increasingly prevalent during that period. Another possible reason is that some types of insanity, especially manic-depressive illness, may produce more creativity. The relationship between insanity and creativity has been debated since ancient times.

Q: What is causing the epidemic of insanity?

Torrey:  No one, of course, knows for certain. But in looking at the pattern of increase over the past two centuries, it seems clear that the increase was unrelated to social and economic crises—wars, depressions, etc. The increase does appear to coincide with industrialization and especially urbanization in general and is almost certainly biological. Our own research has investigated infectious agents as a cause of schizophrenia and manic-depressive illness, and that theory fits nicely with the observed rise in insanity. Other biological factors that should be considered include changes in diet and exposure to toxins.

Q: Are you saying that Michel Foucault’s Madness and Civilization as well as Thomas Szasz, Andrew Scull, David Rothman, et al. are wrong?

Torrey & Miller: Yes, Foucault, Szasz, Scull, Rothman, and other writers who have claimed that insane asylums were built merely to put away troublesome people got it completely wrong. The evidence we discuss in the book makes it clear that insane asylums were built in response to a perceived need to accommodate increasing numbers of insane persons.

Q: What can we do to stop this epidemic?

Torrey & Miller: First, we need to recognize the reality of the epidemic. For example, when we look at the increasing numbers of homeless mentally ill persons, we should view them as the consequence of 250 years of rising insanity, not as some recent social aberration. Second, we need to develop data to track the numbers of insane persons over time; remarkably, we are not now doing this. Third and most important, we need to markedly increase our research efforts on the causes and treatment of schizophrenia and manic-depressive illness. The National Institute of Mental Health has failed badly in these efforts. Can you imagine having ignored the epidemics of tuberculosis or AIDS, and failing to do research on these diseases? That is the situation with epidemic insanity, which is why we call it an invisible plague.