Clinical studies (also called clinical trials) are studies that involve human subjects with informed consent. In the case of HD, these studies have been critical in identifying the various symptoms that doctors now use to diagnose the disease (For more information on symptoms of HD, click here). In fact, the very name “Huntington’s Disease” comes from Doctor George Huntington, who was the first to notice that many of his patients’ symptoms were part of the same disease.
Now that the symptoms and typical age of onset of HD are clearly defined, clinical studies today are more geared toward judging the effectiveness of particular drug treatments. After a new drug passes the test in animal studies, the U.S. Food and Drug Administration requires that clinical studies be performed to ensure that the drug is safe for humans. Once approved by the Food and Drug Administration, drugs may be sold either as prescription drugs or over-the-counter drugs.
Several clinical studies regarding potential drug treatments for HD are either currently underway or have recently produced results. One study that was published in August of 2001 examined the effectiveness of two drugs, coenzyme Q10 (also called “CoQ10”) and remacemide. CoQ10 exists naturally in the body and is key to the function of mitochondria (the so-called “energy factories” of cells) and in combating harmful chemicals called free radicals, which may play a role in nerve cell death. Remacemide is an engineered drug that has been shown to block a receptor for glutamate, a neurotransmitter that has also been implicated in causing nerve cell death.
Since nerve cell death leads to the manifestation of HD symptoms, researchers believed that treatment with remacemide and nutritional supplements of CoQ10 would stop the cell death and thus reduce the symptoms of the disease. Unfortunately, the results of the research were not very promising: over the 2.5 year span of the study, patients who had been receiving remacemide were no better off in terms of symptom progression than patients who had been receiving a placebo pill. The progression of symptoms was slowed by approximately 13% in patients who were receiving CoQ10 (in comparison to those who were not receiving CoQ10), but the researchers who conducted the study admitted that these results could have been due to chance. If this is the case, then the 13% difference in symptom progression may be statistically insignificant, meaning CoQ10 may have no real effect on HD at all. Thus, the results of this clinical study suggested that treatment with remacemide and/or nutritional supplements of CoQ10 is unlikely to be helpful in combating the symptoms of HD.
One of the clinical studies that is currently (as of January, 2003) recruiting subjects is called “CREST-HD”. The purpose of this study will be to determine whether or not supplements of a substance called creatine can be used as an effective treatment to combat the symptoms of HD. Creatine exists naturally in the body and (in its related form called phosphocreatine) plays a key role in stabilizing cell membranes, preventing cells from depleting energy, and performing other functions to protect nerve cells. (For more information about creatine, click here). Animal studies using creatine have shown evidence that it can relieve nerve cells from oxidative stress, a harmful phenomenon that injures cells and may lead to cell death. Animal studies have also shown that creatine can directly inhibit apoptosis (early cell death), thus keeping cells alive. Since studies of human athletes have proven that taking creatine supplements can enhance athletic performance (indeed, many professional athletes take creatine supplements), researchers believe that creatine supplements might be able to reverse the weakness and loss of muscle mass that result from HD. The CREST-HD study will examine whether or not the same benefits of creatine that have been observed in animal studies and studies of human athletes will be seen in HD patients. For more information about the CREST-HD study, go to www.clinicaltrials.gov and type “Huntington’s Disease, creatine” in the search engine.
For more information about a wide variety of HD research (organized according to the institutions conducting the research), click here.
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-M. Stenerson 3-08-03
For Further Reading:
Freeman, T. B.; Cicchetti, F.; Hauser, R. A.; Deacon, T. W.; Li, X.-J.; Hersch, S. M.; Nauert, G. M.; Sanberg, P. R.; Kordower, J. H.; Saporta, S.; Isacson, O. : Transplanted fetal striatum in Huntington's disease: phenotypic development and lack of pathology. Proc. Nat. Acad. Sci. 97: 13877-13882, 2000. A technical paper regarding the transplantation of fetal neurons.
Robbins, C.; Theilmann, J.; Youngman, S.; Haines, J.; Altherr, M. J.; Harper, P. S.; Payne, C.; Junker, A.; Wasmuth, J.; Hayden, M. R. : Evidence from family studies that the gene causing Huntington disease is telomeric to D4S95 and D4S90. Am. J. Hum. Genet. 44: 422-425, 1989. A technical paper regarding a particular linkage study that showed the Huntington gene to be located on chromosome 4.
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