Amphetamines may slow Parkinson’s disease
Amphetamines, including the party drug Ecstasy, have reversed the effects of Parkinson’s disease in mice, a new study suggests.
Their finding does not suggest the use of illegal drugs to treat the incurable brain disease, but may offer a way forward in helping patients, they said.
The team at Duke University in Durham, North Carolina treated mice that were genetically modified to develop Parkinson’s-like symptoms with more than 60 types of amphetamines.
Fourteen of the drugs helped reverse the symptoms of the mice, including the tremors and rigidity that mark the disease - raising the possibility of exploring related treatments for humans.
“We hope to find new drugs that are close chemically, but safe,” Marc Caron, who led the research, said in a telephone interview.
Parkinson’s disease is caused by the death of brain cells that control physical movement and produce the essential chemical dopamine.
According to the American Parkinson’s disease Association, there are about 1.5 million Americans with the disease.
The new research shows that dopamine replacement, so far the most common but only partly effective Parkinson’s treatment, may not be the only viable option, Caron said.
Amphetamine-like drugs, not unlike those now given to children with attention deficit disorder, could eventually be used for Parkinson’s disease, he said.
“We give these drugs in low doses to children, so it’s not so terrible to say some day we should give similar drugs to Parkinson’s patients,” Caron said.
Parkinson’s disease Symptoms
Parkinson’s disease usually begins as a slight tremor or stiffness involving the arm or leg on one side of the body. The tremor is prominent at rest and is regular, typically occurring at a rate of three to six times per second. The Parkinson’s disease tremor usually worsens under stress, improves when the arm or leg is moved voluntarily, and may disappear entirely during sleep. In the earliest stages, Parkinson’s disease may be evident only as a tremor involving the thumb and index finger. This tremor sometimes is called “pill-rolling” tremor because it looks as if the person is manipulating a small object such as a pill.
As the illness progresses, the tremor may become more widespread, and eventually affect limbs on both sides of the body. Handwriting may become small, shaky and eventually illegible. In addition to the classic tremor, Parkinson’s disease often causes stiffness or rigidity in the muscles of the arms or legs and a slowing of body movements (bradykinesia).
The rigidity and bradykinesia can be the most disabling aspects of the disease. They can impair the person’s ability to walk and to perform activities of daily living, such as washing, dressing or using eating utensils. Problems with unsteady balance and posture may make it hard for a person with Parkinson’s disease to sit down in a chair or to rise from one. Walking is accomplished with small, shuffling steps and a stooped posture, usually without the normal arm-swinging motions. Bradykinesia can affect the facial muscles, decreasing spontaneous facial expressions and normal eye blinking.
The effects of another stimulant, coffee, have been cited in the past as easing Parkinson’s symptoms by keeping dopamine levels high.
But Caron said coffee is only effective in early stages of the disease, when some dopamine is still present. His new study reflects treatment during advanced stages, when there is no longer any dopamine present.
Ecstasy, also know as MDMA, proved the most effective of the amphetamines used at counteracting Parkinson’s symptoms in the mice, said Raul Gainetdinov, who also worked on the study. He said he is not sure exactly why.
“We do not advocate self-medication with Ecstasy,” Gainetdinov added in a telephone interview. He said that apart from being illegal and controversial, the drug can be more damaging to human nerve tissue than it is to mice.
Caron and Gainetdinov’s findings were published in the August edition of Public Library of Science Biology.
Revision date: July 9, 2011
Last revised: by Janet A. Staessen, MD, PhD