Tardive Dyskinesia Pathology
The practice of using pharmaceutical drugs for the treatment of mental illness is fairly new practice, dating back approximately 60 years. The widespread and growing use of psychoactive drugs to treat mental illness is arguably a case in which the "cure" may be worse than the "disease."
Today, increasing numbers of ethical psychiatrists, such as Dr. Peter Breggin, are realizing that such drugs can be extremely dangerous medications.
Tardive dyskinesia can be a severe side effect of antipsychotic medications. Symptoms such as facial tics and jerking, spasmodic movements are commonly expressed in patients with tardive dyskinesia..
Think of the nervous system as the body's wiring and the neurons as a delivery system. The brain uses this wiring to send electro-chemical signals to various parts of the body, controlling its functions. The space between neurons and between neurons and cells is called a synapse. In order to transmit electro-chemical signals across these synapses, another biochemical, called dopamine, is necessary.
Neuroleptic drugs used to treat psychosis are also called dopamine antagonists. They work to slow or block the action of dopamine. There are actually different types of dopamine receptors used by the nervous system and the medications implicated in the development of tardive dyskinesia are used to target what is known as dopamine receptor D2. The problem with early psychoactive drugs such as Reglan is that they were not particularly selective. The medications would affect a whole range of "D2-like" receptors that may or may not have been a factor in the patient's mental disorder.
Dopamine must be carefully regulated. Too much (which can be caused by overuse of stimulants) and the patient may lose interest in pleasurable activities or suffer from a shortened attention span. Too little (due to the use of depressants and certain psychoactive drugs) and the result can be hyperactivity, including the tics and spasms associated with tardive dyskinesia.
This is a simplified explanation, of course, but to carry the machine analogy further, the situation might be compared to what happens when an electrical appliance rated at 40 watts suddenly receives a surge of 100 watts. The machinery will operate in an erratic manner and ultimately burn out if the current is not regulated properly.