Horror, Sleaze and Trash.

Nash began to show signs of extreme paranoia and his wife later described his behavior as erratic, as he began speaking of characters like Charles Herman and William Parcher who were putting him in danger. Nash seemed to believe that all men who wore red ties were part of a communist conspiracy against him. Nash mailed letters to embassies in Washington, D.C., declaring that they were establishing a government.^[8][9]

He was admitted to the McLean Hospital, April–May 1959, where he was diagnosed with paranoid schizophrenia. The clinical picture is dominated by relatively stable, often paranoid, fixed beliefs that are either false, over-imaginative or unrealistic, usually accompanied by experiences of seemingly real perception of something not actually present — particularly auditory and perceptional disturbances, a lack of motivation for life, and mild clinical depression.^[10] Upon his release, Nash resigned from MIT, withdrew his pension, and went to Europe, unsuccessfully seeking political asylum in France and East Germany. He tried to renounce his U.S. citizenship. After a problematic stay in Paris and Geneva, he was arrested by the French police and deported back to the United States at the request of the U.S. government.

In 1961, Nash was committed to the New Jersey State Hospital at Trenton. Over the next nine years, he spent periods in psychiatric hospitals, where, aside from receiving antipsychotic medications, he was administered insulin shock therapy.^[10][11][12]

Although he took prescribed medication, Nash wrote later that he only took it under pressure. After 1970, he was never committed to the hospital again and refused any medication. According to Nash, the film A Beautiful Mind inaccurately showed him taking new atypical antipsychotics during this period. He attributed the depiction to the screenwriter (whose mother, he notes, was a psychiatrist), who was worried about encouraging people with the disorder to stop taking their medication.^[13] Others, however, have questioned whether the fabrication obscured a key question as to whether recovery from problems like Nash's can actually be hindered by such drugs,^[14] and Nash has said they are overrated and that the adverse effects are not given enough consideration once someone is considered mentally ill.^[15][16][17] According to Sylvia Nasar, author of the book A Beautiful Mind, on which the movie was based, Nash recovered gradually with the passage of time. Encouraged by his then former wife, de Lardé, Nash worked in a communitarian setting where his eccentricities were accepted. De Lardé said of Nash, "it's just a question of living a quiet life".^[18]

Nash dates the start of what he terms "mental disturbances" to the early months of 1959 when his wife was pregnant. He has described a process of change "from scientific rationality of thinking into the delusional thinking characteristic of persons who are psychiatrically diagnosed as 'schizophrenic' or 'paranoid schizophrenic'"^[19] including seeing himself as a messenger or having a special function in some way, and with supporters and opponents and hidden schemers, and a feeling of being persecuted, and looking for signs representing divine revelation.^[20] Nash has suggested his delusional thinking was related to his unhappiness, and his striving to feel important and be recognized, and to his characteristic way of thinking such that "I wouldn't have had good scientific ideas if I had thought more normally." He has said, "If I felt completely pressureless I don't think I would have gone in this pattern".^[21] He does not see a categorical distinction between terms such as schizophrenia and bipolar disorder.^[22] Nash reports that he did not hear voices until around 1964, later engaging in a process of rejecting them.^[23] Nash reports that he was always taken to hospitals against his will, and only temporarily renounced his "dream-like delusional hypotheses" after being in a hospital long enough to decide to superficially conform, behave normally or experience "enforced rationality". Only gradually on his own did he "intellectually reject" some of the "delusionally influenced" and "politically-oriented" thinking as a waste of effort. However, by 1995, he felt that although he was "thinking rationally again in the style that is characteristic of scientists," he felt more limited.^[19][24]