We often see people on the streets who appear seriously mentally ill – arguing with the voices in their heads, yelling at all who pass by, unable to keep themselves clean. Especially with “deinstitutionalization,” the closing down of psychiatric hospitals about 50 years ago, the psychologically damaged seem everywhere. Their presence suggests that rates of acute mental illness have soared in recent generations. Have they? Being able to track actual rates of mental illness is quite difficult, but the bits of evidence we have suggest that serious psychological illness — let’s bracket neuroses for another time — were probably greater in earlier centuries than in recent decades.
Start with an anecdote: Abraham Lincoln was famously a melancholy soul and not only because of the war. Even as a young man, Lincoln frightened his friends with spells of depression and intimations of suicide. Distress was all around him. Lincoln’s father had episodes of the “blues”; the violent madness of a 19-year-old neighbor impelled Lincoln to write a poem about the “howling, crazy man”; and the widowed Mary Todd Lincoln attempted suicide. Lincoln’s story illustrates historian Page Smith’s thesis that “anxiety and despair, as much as confidence and optimism, have characterized our history from the beginning.”
One might try to track mental illness historically in rates of admissions to mental institutions. But changes in those rates more closely reflect changing policies toward mental illness than illness itself. Between 1903 and 1940, the number of Americans in state mental hospitals roughly tripled mainly because officials began the institutions to house the elderly poor or other bothersome people. In the 1960s, state governments emptied out the mental hospitals as part of a yet newer reform.
Changes in how doctors diagnose people also shape our counts of the mentally ill. In the 1810s, Philadelphia doctors replaced many diagnoses of insanity with “delirium tremens” (alcohol withdrawal) as a label more suitable for middle-class men. In the 1970s, the American Psychiatric Association decided that homosexuality was no longer to be classified as a disorder; instantly, millions were no longer “ill.” More recently, diagnoses of bipolar disorder increased 4,000 percent in just one decade; obviously it was not the illness that increased. Recent controversies over the latest Diagnostic Manual (e.g., here) illustrate the point.
Still, we can get some broad sense of the long-term historical trends. Mental illness was well-known in colonial and 19th-century America. Page Smith points to the “cosmic loneliness” of life in the wilderness, to anxieties about salvation, to common reports of upset stomachs, and to high rates of alcoholism among early Americans. 
Often, the disturbed were simply tolerated: a Watertown, Mass. schoolmaster in the 1740s, for example, occasionally strode about town naked and sometimes had to be dragged out of meetings for creating a disturbance; a Carolina man lived in a hollow log, ranted about witches, and pulled out fourteen of his teeth because he thought his kinfolk were hiding inside them.
To get officially noticed as insane, people had to really act out or repeatedly endanger lives. Thus unlisted in any records were the many more Americans whose functioning was not so impaired (they may have been “blue” like Lincoln’s father or even suicidal as Lincoln may have been) and those who, even if quite ill, found care among relatives. The family of John Wells, a South Carolina farmer, kept him chained and handcuffed for ten years before sending him to an asylum. During the religious fervor of the Great Awakening, families sometimes locked up relatives at home for becoming “furiously insane” on faith. 
Such stories, of course, do not give us any clear sense of how frequent disorders were. Still, biographies, passing accounts, and literary references suggest that serious mental illness was probably more common in the 18th and 19th centuries than in the 20th.
Of more substance are reports that farm women, particularly in the sparsely settled West, suffered greatly from mental distress; their depression became one of the key “Country Life” problems investigated in the 1900s during the Theodore Roosevelt administration. At about the same time, in the bursting cities, native migrants and foreign immigrants contributed substantially to the national tally of mental illness. Their distress appears in well-publicized suicides then. The overall rate of suicide has not, however, in net changed since. (See this recent post on suicide.)
Addiction is both a psychological problem itself and often a reflection of yet deeper ones. Alcohol addiction was rampant in early America. Although it abated over the 19th century, many Americans, notably middle-class women and Civil War veterans, became addicted to drugs – morphine, opium, laudanum, and cocaine.
Many, if not most, probably got hooked after their doctors prescribed one to treat any of a vast array of common physical and psychological symptoms. For example, an opium dealer remarked in 1877 that “since the close of the [Civil] War, [Southern] men once wealthy, but impoverished by the rebellion, have taken to eating and drinking opium to drown their sorrows.” Medical practice changed, new laws curtailed some drugs, and eventually drug addiction in the twentieth century declined, at least among the middle class.
Against this background, psychological disturbance in modern America, although certainly significant and important, is relatively muted. (The last few years of economic distress has, however, spiked emotional distress.) In Made in America, I discuss the trends of the last few decades, trends that we can better measure. I conclude that, despite the psychotics in the streets and the ever-broadening diagnoses of mental illness, overall rates of serious psychological disorder are no higher and probably lower than they were in earlier centuries. (See this post on depression.)
Not that knowing this makes the street encounters any less disturbing.
 Much of what follows draws from Ch. 6 of Made in America.
 Smith, “Anxiety,” Wm. & Mary Quart., 1969.
 McCandless, Moonlight, Magnolias, & Madness, p. 21.
Cross-posted from Claude Fischer’s blog, Made in America: Notes on American life from American history.