Amantadine has been used for Parkinson’ s since the 1960s. It can be effective against the PSP gait disorder even if Sinemet is not, possibly because it affects more than just the dopamine system. Its benefit generally lasts only a few months, however. Its principal potential side effects are dry mouth, constipation, confusion, swelling of the ankles, and a pink skin discoloration in a lacy pattern called livedo reticularis. In people with PSP, the dosage should be kept low, generally no more than 200 mg per day, because of the potential for confusion or agitation.
Drugs for dementia, including Aricept( donepezil), Reminyl( galantamine), and Exelon( rivastigmine), enhance the activity of the brain chemical acetylcholine and are modestly useful against the dementia of Alzheimer’ s disease. They can also be somewhat useful in Parkinson’ s disease and other forms of dementia. None of them has been found helpful in PSP, but rivastigmine is probably worth trying. A fourth anti- Alzheimer drug, Namenda( memantine), acts on a different brain chemical, glutamate. It works no better for PSP than the others and can cause confusion and agitation in patients with PSP.
Although the jury is still out, one possible success story is the dietary supplement Coenzyme Q-10( CoQ10), which is available without a prescription. It helps the body’ s cells produce energy from sugar and oxygen and is a normal constituent of the mitochondria, the tiny compartments in our cells where that chemical process occurs. One small study gave modestly favorable results. Another gave similar benefit but was too small to be sure that its outcome was not just the result of chance. The required dosage of the standard formulation of CoQ10 is probably at least 1,200 mg per day and perhaps as high as 2,400 mg. The newer liposomal form probably gives the same benefit at 300 mg per day. As a nonprescription item, CoQ10 is not covered by drug insurance and costs $ 50 to $ 100 month. Therefore, people with PSP should carefully consider the meager evidence to date for the benefit of CoQ10 before taking that long-term financial plunge. Their neurologists should do a careful exam upon starting the drug and repeat it two months later to determine whether the treatment is working, and if not, discontinue it.
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Botox or Myobloc, two types of botulinum toxin, are a different sort of drug that can be useful for people whose PSP is complicated by blepharospasm. A very dilute solution of the toxin, which is produced by certain bacteria that can contaminate food, can be carefully injected by a neurologist into the eyelid muscles as a temporary remedy for abnormal involuntary eyelid closure. Botox can also be used for involuntary turning or bending of the head that occurs in PSP, but injecting it into the neck muscles can sometimes cause slight weakness of the nearby swallowing muscles. In PSP, where swallowing is already impaired in many patients, caution should be used when considering use of Botox in neck muscles.
What about other experimental drugs?
In the past 20 years, many drugs have been tested in patients with PSP. Some of these are intended to actually slow the long-term brain cell loss, thereby slowing the progression of the disease. Unfortunately, none has helped. The most promising were riluzole, which modestly helps amyotrophic lateral sclerosis( ALS); davunetide, which is a fragment of a protein that helps maintain brain cells’ internal skeletons; and tideglusib, which prevents the abnormal attachment of phosphate to the tau protein, preventing it from clumping up in the brain cells.
The last drug, tideglusib, did show a glimmer of promise: MRI scans showed less loss of brain mass in the patients on tideglusib than in those on placebo. This may justify further study of the drug, but it is doubtful that any drug company will want to pursue it after it failed to slow progression of the actual symptoms of the disease.