The side effects and functions of psychiatric drugs are often little known or understood, presenting something of a problem for society as more and more people find themselves proscribed a wide variety of drugs. These drugs can be very useful, allowing people who once would have had no place in mainstream society to function and interact in a relatively normal way and have productive lives. This does not mean that there is no cost to balance against the possible benefits.
The term tardive dyskinesia was first coined in 1964 to describe a form of dyskinesia – or movement disorder – which appeared in people who had taken either high doses or long term doses of certain kinds of drugs called dopamine antagonists. People who take these drugs are at risk of developing tardive dyskinesia. Dopamine antagonists are used in the treatment primarily of neurological disorders, commonly as antipsychotics. Along with that, they may be used in the treatment of some gastrointestinal disorders.
The symptoms of tardive dyskinesia involve any number of repetitive movements that a person experiences outside of their control and to no particular purpose. These movements may be any numver of things, ranging from small unobtrusive tics to the rapid, involuntary movement of the extremities, and can include rapid blinking, grimacing, tongue protrusion, lip smacking, pursing or puckering. Symptoms of tardive dyskinesia can continue even after the drugs which brought it on are no longer being used, which is what “tardive” means in this context. Taken together, tardive dyskinesia is nothing but a descriptive term for the experience of the people who develop it – lasting uncontrolled movement. Tardive dyskenisia may be similar to other related diseases, such as tardive dystonia, tardive tourettism, and tardive akathisia. Parkinson’s could be viewed as an opposite of tardive dyskinesia in terms of presentation; where Parkinson’s patients have difficulty moving, tardive dyskinesia patients have difficulty not moving.
Despite the fact that tardive dyskinesia has been around and identified for the better part of the last fifty years, the exact underlying causes for it are less well known. The best theory at present for what causes the symptoms of tardive dyskinesia is damage to the systems within the human body which use and process dopamine. Dopamine is a neurotransmitter which occurs in a wide variety of animals, from invertebrates to vertebrates, and including humans. Dopamine serves many functions within the body, among them helping to regulate movement. By changing the body’s sensitivity to dopamine, dopamine antagonists change how a person moves, which in theory, leads to tardive dyskinesia.
Tardive dyskinesia normally occurs within people with psychiatric disorders who have been treated with antipsychotic medications for several years. Several studies have been done investigating the rate at which people develop tardive dyskinesia. The data from these studies shows that, among other factors, not everyone responds the same to the same dosage of the same medication. This means that for whatever reason, not everyone on dopamine antagonists for an extended period of time will develop tardive dyskinesia. However, some studies have indicated that over years of use, as many as nearly a third of patients may show signs of tardive dyskinesia after five years of antipsychotic drug use. The rate at which people develop tardive dyskinesia increases over time, and so far studies have not indicated an upper limit.
The best treatment for tardive dyskinesia is prevention. Using the lowest effective dosages of antipsychotic drugs for the least time, and discontinuing or diminishing use of those drugs when symptoms begin to show. Unfortunately, for some people prevention is impossible. The benefits of psychiatric medications outweigh the risks of twitching or rapid blinking, making the trade off worthwhile. For people in those situations, there are some medical treatments which have been shown to improve the symptoms of tardive dyskinesia.
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