Much of the mystery surrounding drug action can be cleared up by recognizing that drugs affect only the rate at which biologic functions proceed; they do not change the basic nature of existing processes or create new functions. For example, drugs can speed up or slow down the biochemical reactions that cause muscles to contract, kidney cells to regulate the volume of water and salts retained or eliminated by the body, glands to secrete substances (such as mucus, gastric acid, or insulin), and nerves to transmit messages. How well the drug works generally depends on how well the targeted processes respond.
Drugs can alter the rate of existing biologic processes. For example, some antiepileptic drugs reduce seizures by sending the brain an order to slow down production of certain brain chemicals. However, drugs can't restore systems already damaged beyond repair. This fundamental limitation of drug action underlies much of the current frustration in trying to treat tissue-destroying or degenerative diseases such as heart failure, arthritis, muscular dystrophy, multiple sclerosis, and brain tissue detroying neurological diseases.
All of the prescription drugs presently available are designed to treat only the symptoms of degeneration diseases of the brain such as Alzheimer's and Parkinson's. They neither cure the diseases nor are they known to slow or change their eventual course.
There are some neurological diseases where no prescription drugs have been accepted as being effective in treating symptoms. Still doctor's, in an attempt to offer some help, will "try" these medications mostly in the hope they will help. There is no guidance available for them in their search for a viable treatment and so one doctor may retry a medication that has been found by another doctor to offer little or no help for a specific condition.
The results of these "trials" vary. Sometimes it will appear that the condition of the patient hasn't changed. Other times the patient may acquire new symptoms caused by the side-effects of the medications and thus cause the original disease diagnosis to be questioned. And there is always the risk that the medication will speed-up the progression of the disease, increase the possibility of dementia or/and causing additional unrepairable brain damage. Remember too that the body must be able to neutralize all medications and remove them from the body or they will be stored in the body and eventually rise to harmful levels.
Still, sometimes these "trials" appear to help some symptoms for a time for some even though for others they may be ineffective or seem to have adverse side-effects. Whether the improvement is real or imagined is often debatable.
It other cases the improvement in the quality of life is real and can be traced directly to the use of the medication. It's entirely possible in these instances that the "untreatable" disease has been misdiagnosed and is something whose symptoms can be treated with the trial medication.
So, it's important to study any recommendation concerning the used of any medication used to treat the symptoms of a neurological condition otherwise considered to be "untreatable". It's important to learn all you can about all your medications, what they are intended to treat and what adverse side-effects they can cause. Check all the available information closely and get the best available current advice before you agree to any particular course of treatment.
Some conservative doctors prefer not to prescribe drugs to treat any parkinsonian or neurological symptom unless they are extremely necessary because of the possible side-effects and the belief that any relief is temporary, the danger of side-effects is too great or that their use may eventually speed up the progression of the disease.
Sometimes less treatment is really the best treatment.
When in doubt ask your doctor! Also remember second opinions are usually available.