Drapetomania

Drapetomania is a bit of racist, pre-Freudian quack psychology. This unusual psychological condition was only observed in black slaves during the early 1800s. Symptoms of drapetomania include a refusal to accept one's Biblically-ordained position as a sort of human livestock and the tendency to head northward at high speed in the middle of the night. The cure, unsurprisingly, was to rough up any slaves that show symptoms until symptoms disappear.

Origin
Data from a profoundly flawed 1840 US census apparently showed that free black people were more likely to be 'insane and idiotic' than enslaved black people. Based on this census, in 1842, physician wrote a paper in a well regarded medical journal titled "Insanity among the coloured population of the free states." Jarvis' report was the best known, but only one of many. After Jarvis' 1842 publication, 18 months later, he reexamined the data and decided that his initial conclusion was incorrect. Supporting the conclusion that the 1840 census was flawed, the 1850 census would show no such evidence that freedom was associated with insanity.

The idea that freedom caused madness was one that did not easily go away, however, because there was a lot of money to be made by slave owners who could use its existence as an argument against abolitionism. Drapetomania (from the Greek δραπέτης or drapetes, "a runaway [slave]" + μανία or mania, "madness, frenzy") was claimed to be a disease in a paper written by Samuel Adolphus Cartwright, a physician and early germ theory denialist practicing in America's antebellum South. Cartwright was a doctor with a strong support of the slave-holding South and threw his full intellectual weight into the support of slavery, writing essays in various magazines to champion segregation and slavery from political, social, Biblical and pseudoscientific angles.

Dr. Cartwright's first article on Drapetomania seems to have appeared in May 1851, in the New Orlean's Medical and Surgical Journal. It was referenced in several articles in the (pro-slavery) southern magazines Southern Quarterly Review and DeBow's Review, referenced in Fredrick Law Olmstead's The Cotton Kingdom: a Traveler's Observations on Cotton and Slavery in the American Slave States and sarcastically lampooned in the Buffalo Medical Journal.

What's The Deal?
Drapetomania is, at its heart, half-biological determinism, half-Biblical predestination rationalized through the utility of slavery in the contemporary social structure and economy. Since Cartwright saw black people as slaves and slaves as useful to the Southern economy, this became his context for normal function. Assuming Cartwright was sincere, he conflated normal with healthy and deviations from "normal" (coerced) activity as unhealthy.

A black person, as a "healthy organism", would operate contently in slavery. Departure from this norm was, then, "unhealthy".

This practice of creating mental disorders in the name of social or economic convenience continued on into the 20th century, when Soviet psychiatrists used "sluggish schizophrenia", an alleged mental disease with symptoms vague enough to cover virtually anything to justify locking up dissidents. There are still remnants of this practice today, though the qualifications of people who do this have declined dramatically. Now it's mainly relegated to media or internet blowhards who declare that feminism or liberalism is a mental disorder, for example.

The Wrong Samuel Cartwright
Due to the fast and loose exchange of information on the internet, websites and blogs mentioning drapetomania often give out the factoid that the discoverer of this bunk malady was actually a dentist, not a psychologist or physician.

This is not true. The discoverer of Drapetomania was a physician in private practice and with the Confederate medical corps. This misinformation comes from the conflation of Samuel Adolphus Cartwright (1793-1863), American/Confederate doctor with the similarly named (1789-1864), assistant dentist to King George IV of England (and all around sociable guy), who lived in roughly the same time period.