Convulsive therapy
Convulsive therapy is the deliberate and controlled induction of a seizure or other disturbance of brain function for the purpose of psychiatric treatment.  Convulsive therapy attempts to produce this state artificially and under controlled conditions, on the premise that seizures can induce improvement in the patient's mental state once the patient recovers.

# History
Physicians have noticed for thousands of years that a person's mental state sometimes changes dramatically following recovery from a seizure whether induced by a head injury, an intense febrile illness such as malaria, or chemically induced loss of consciousness or convulsions.  In the time of the Roman Empire, for instance, electric fish were used to provide electric shocks to ill patients. For example, Scribonius Largus used it in AD 47 for treating persistent headaches. It is said that the Emperor Claudius himself was one of his patients.
Other instances of medical use of convulsive therapy were Paracelsus, who used seizures induced by camphor to treat psychosis in the 16th century; Drs. Jean LeRoy (France, 1745), Robert Whytt (London, 1751) and Leonard Yealland (London, 1917), all of whom used weak (non-convulsive) faradic electrical shocks to treat various "nervous, hypochondriac, or hysteric" cases as well as men suffering "shell-shock."
The rationale which supported the convulsive treatment strategy may also have been partly related to the 18th century rational in medicine which saw the 'breaking of the will' of the patient as necessary to cure insane persons.
With the rise of more biological explanations for mental disease at the end of the 19th century, the search for biological treatments also increased. In a short decade between the 1920s and the 1930s, several methods were developed by scientists who started to experiment with seizure-inducing techniques. Due to the absence of any effective therapeutic approaches to mental disease, and because it sometimes lead to remarkable immediately observable changes in patients, in the next two or three decades convulsive therapy became one of the most widely used tools of psychiatry. Hundreds of thousands of patients were subjected to it, including many important personalities, such as writers Ernest Hemingway and Janet Frame, poets Sylvia Plath and Robert Lowell, performer Paul Robeson, rock star Lou Reed, film actresses Frances Farmer, Vivien Leigh, Clara Bow and Gene Tierney, pianists Vladimir Horowitz and Oscar Levant, talk show host Dick Cavett, mathematician John Forbes Nash, author and philosopher Robert Pirsig and politician Thomas Eagleton.
Though popular in the first half of the 20th century, most convulsive therapies are now considered ineffective or too risky for general use. Only electroconvulsive therapy- also referred to as ECT- is still used today. It is reserved for particularly severe, treatment-resistant and life-threatening mental illness.

# Methods
Various types of convulsive therapy were common until the mid or late 20th century. However, doubts over long-term benefits, ethical concerns, and advances in psychiatric drugs, psychotherapies and supportive services led to decreased use. Under this definition of convulsive therapy, which excludes similar treatments involving the passage of current through the body for therapeutic ends such as cardioversion and defibrillation, electroconvulsive therapy is the only type of convulsive therapy still practiced in the 21st century, though controversial and intended to be mainly restricted to severe cases of depression and bipolar disorder which have not responded to other kinds of therapies.
- Electroconvulsive therapy or ECT, involves inducing a grand mal seizure in a patient by passing an electrical current through the brain. It was discovered by Italian researchers Ugo Cerletti (1877-1963) and Lucio Bini (1908-1964). It is used today, albeit with restricted indications, such as usually treatment resistant depression or bipolar affective disorder and obsessive-compulsive disorder or anxiety disorders. In these cases, it is considered a safe and effective procedure, when carried out under a clinical protocol which involves EEG monitoring, application of muscle blocking agents and general anesthesia or sedation.  A typical course of ECT involves between six and twelve treatment sessions spaced every other day.  The number of treatments is determined by the rate of the patient's response.
- Malarial fever therapy involves the inoculation of malarial protozoa into the bloodstream of patients, in order to provoke episodes of intense fever and unconsciousness, which are sometimes followed by convulsions. The method was discovered by an Austrian physician Julius Wagner-Jauregg (1857-1940) in the 1910s, who got the Nobel Prize for his discovery in 1927. For a while, it was used for treating the general paresis of the insane, caused by tertiary syphilis. It is no longer used.
- Insulin shock therapy involves injecting a patient with a large amount of insulin, which causes convulsions and coma by provoking brain hypoglycemia. It was discovered by Polish physician and researcher Manfred Sakel (1900-1957) in 1933 and was used well until the 1950s for the treatment of depression and psychosis. However, the insulin coma could become irreversible, and a 1939 report found the procedure had a 1.3% mortality from this cause . It is also rarely used now.
- Metrazol shock therapy involves injecting a patient with Metrazol (cardiazol), a drug that quickly induces powerful brain seizures. It was discovered by Hungarian physician and researcher Ladislas J. Meduna (1896-1964) in 1934 and further researched by Francis Reitmann  It was soon superseded by electroconvulsive therapy, because it was difficult to control and had many adverse effects. The violence of the convulsions produced hairline fractures in the vertebrae of many patients, especially those who already suffered from vitamin D deficiency due to the poor diet in psychiatric hospitals .
- Pharmacological shock was a general term for convulsive therapy by injecting chemicals such as insulin or metrazol .  Psychiatrists in the 1930s also experimented with other chemicals including camphor  or ammonium chloride  to induce convulsions in their patients.

# Mechanisms of action
The mechanism of action by which convulsive therapies might exert any lasting effect is unknown. A generic defense mechanism might be at work following a seizure. Alternatively a post-traumatic stress reaction might be induced. Long-standing neural networks or cognitive-behavioural patterns, associated with psychopathology, could potentially be disrupted.
When convulsive therapies were most used, science had no effective tools to study their effects. Studies about the underlying mechanism of electroconvulsive therapy, commonly known as ECT, still continue. Many hypotheses have been proposed, including potential effects on neurotransmitters, but the precise mechanism remains elusive.