At the moment, medicine has no way to cure or slow the progression of the disease-only ways to manage the symptoms. But a number of natural agents, including a red-wine compound and a popular nutritional supplement, are being studied for their potential against HD-with very promising results.
This vitamin-like compound, widely available as a nutritional supplement, is being investi-gated for HD because of its ability to support the function of mitochondria-the tiny 'power plants' that provide every cell in the body with energy. Mitochondrial dysfunc-tion is known to contribute to the neurodegenerative process in HD, so CoQ10 could, in theory, provide therapeutic benefit (J Neural Transm Suppl, 2004; 68: 111-6).
Researchers at the UCLA David Geffen School of Medicine in Los Angeles, CA, recently tested this theory in mice that had been genetically engineered to develop the symptoms and brain changes that mimic human HD. They discovered that feeding the mice CoQ10 led to improve-ments in early behavioural problems as well as to positive genetic changes, leading to the conclusion that CoQ10 "may be beneficial in HD", particularly if given during the early stages of the disease (Mol Cell Neurosci, 2012; 49: 149-57).
In another mouse model of HD, high-doses of CoQ10 were found to improve motor (movement-related) perfor-mance and grip strength as well as reduce some of the detrimental brain effects that arise with HD, such as the loss of neurons. CoQ10 also appeared to extend the survival rates of the mice, with the highest doses being most effective (Biochim Biophys Acta, 2006; 1762: 616-26).
As these promising results may not necessarily apply to humans, clinical trials in HD patients are currently under-way. So far, the results of the CARE-HD trial by the Huntington Study Group (HSG)-based at the University of Rochester Medical Center in New York-have been encouraging.
A total of 347 patients with early HD were randomly assigned to receive either CoQ10 (300 mg twice daily), a drug under investigation for HD (remacemide hydro-chloride, 200 mg three times daily), both CoQ10 and remacemide or a placebo for two and a half years.
By the end of that time, although none of the groups saw a significant slowing of the disease, those taking CoQ1O showed a trend towards less functional decline-by an average of 15 per cent. These patients continued to be able to handle everyday responsi-bilities such as finances and domestic chores, to retain cognitive skills and to focus their attention better for longer, and were also less depressed and irritable, than those not taking CoQ10. According to lead researcher Professor Karl Kieburtz, a 15-per-cent slowing of decline would roughly translate to about one more year of independence for HD patients (Neurology, 2001; 57: 397-404).
A larger, five-year placebo-controlled trial is now being conducted by the HSG to see what effects a larger dose of CoQ10 (2400 mg/day) might have on people with HD (Neuropsychiatr Dis Treat, 2009; 5: 597-610).
This antioxidant vitamin is another nutrient showing potential for HD. A form of vitamin E called alpha-tocotrienol protected nerve cells from increased free-radical damage and toxicity caused by the neurotrans-mitter glutamate in the lab. The nerve cells of people with HD are especially sensitive to glutamate, so the prevention of glutamate-induced oxidative damage may have an important part to play in the treatment of HD.
In another test-tube study, treatment of nerve cells with alpha-tocotrienol not only decreased cell death, but also helped the cells to grow at a normal rate even when exposure to glutamate was continued (J Biol Chem, 2003; 278: 43508-15).
Overall, however, clinical studies of vitamin E in HD have had mixed results. One early small pilot trial reported that the vitamin was not effective for the disease (Br Med J, 1978; 1: 153), whereas another, much larger, trial had a more positive conclusion. This trial looked at 73 patients with HD who were given either high-dose vitamin E (in the form of d-alpha-tocopherol) or a placebo for a year.
According to the results, vitamin E had no effect on symptoms overall, but further analysis revealed a "significant selective therapeutic effect" on neurological symptoms (those related to the nervous system, such as jerky move-ments, memory loss and walk-ing difficulties) in patients in the early stages of the disease (Am J Psychiatry, 1995; 152: 1771-5).
Vitamin E has also shown promise when used in combination with CoQ10-at least in rats (Neurochem Int, 2006; 48: 93-9).
Better known for its heart-healthy effects, resveratrol-a plant compound found in red grapes, peanuts and pome- granates-is also being investi-gated as a therapeutic agent for HD. Resveratrol has been found to activate the sirtuin 1 (SIRT1) gene, also known as a 'longevity' gene, which appears to have a positive effect in cases of HD.
When this gene was overactivated in mice bred with HD, there were beneficial effects on disease progression, suggesting that SIRT1 may have a neuroprotective role (Nat Med, 2011; 18: 153-8).
Resveratrol is now being tested in mouse and other models of HD, such as in flies and worms, but the results so far have been mixed. One study reported that resveratrol treatment did not lead to significant improvements in motor performance, survival and brain cell loss. However, other studies have reported beneficial brain changes with resveratrol and with a distantly related polyphenol called 'fisetin', found in strawberries, blueberries and the skin of cucumbers (Exp Neurol, 2011; 232: 1-6).
Clinical trials are now needed to see what effects, if any, resveratrol may have on people with HD.
Popular among bodybuilders, athletes and those wanting to gain muscle mass, the amino-acid creatine-widely available as a powdered supplement-has been getting some attention as a potential treatment for HD.
After discovering its positive effects in mice when given before any HD symptoms had appeared, researchers from the Bedford VA Medical Center in Massachusetts investigated creatine's impact on HD when administered after the onset of symptoms. They found that when creatine was given to mice in the early and middle stages of the disease, the animals showed improved motor performance and signifi-cantly extended survival. Mice given creatine during the earlier stages of HD showed the most benefit, with brain changes that indicated slowing of the disease progression (J Neurochem, 2003; 85: 1359- 67).
In preliminary human trials, however, creatine at a dose of 5 g/day for a year did not improve symptoms in patients at various stages of HD. However, this dose was lower than the equivalent dose given to mice, so more trials are currently underway to see if a higher dose is more effective.
An exciting study carried out in Australia suggests that unsaturated fatty acids, such as those found in fish oil, may be beneficial for HD. Seventeen patients with HD were randomly split into two groups: one received highly unsatur-ated fatty acid (HUFA) therapy; and the other was given a placebo. The results showed significant improvement in motor and functional perfor- mance in the patients taking HUFA, while those taking the placebo deteriorated.
"This is the first time that a significant improvement has been noted in a randomized trial in HD," the researchers reported. They also noted that their results were consistent with a previous study in end-stage HD patients, as well as a study in a mouse model of HD (Neuroreport, 2002; 13: 29-33).
Reason for hope
These promising results suggest that there is hope on the horizon for HD. Although HD is a genetic disorder, these findings indicate that it may still be possible to influence the disease to some extent, particularly if treat-ment is begun during the early stages.
Although it will probably be some time before any of these compounds are medically recommended for HD, their good safety profiles and the fact that they are easy to obtain means that HD sufferers could try these supplements if they so wish. A qualified naturopathic doctor may be able to offer advice on dosages and on any complementary nutritional therapies.
Factfile: Symptoms of Huntington's
- Involuntary jerking or writhing movements
- Slow, uncoordinated movements
- Difficulty with speech and swallowing
- Problems with spatial perception
- Difficulty with walking, posture and balance
- Short-term memory loss
- Inability to initiate a task or conversation
- Problems with learning new information
- Tiredness and loss of energy
Factfile: Does keeping active delay HD?
Researchers at the Bruce Lefroy Centre for Genetic Health Research in Victoria, Australia, recently made the exciting discovery that an active lifestyle might delay the onset of Huntington's disease. In mouse models of HD, environmental enrichment was found to significantly delay the first signs of the disease, so the Australian researchers decided to investigate whether there was any connection between the sort of lifestyle people led (active or passive) and the age of disease onset in 154 adults with HD.
The study revealed that those whose daily lives included a high level of passive activities-those that lacked physical and intellectual challenges such as watching television, talking on the phone or working at an unchallenging job-had a disease onset that was, on average, four years earlier than those who had the least passive lifestyles (Mov Disord, 2010; 25: 1444-50).
According to lead researcher Professor Martin Delatycki, "People with a genetic predisposition to the disease could significantly delay its onset by minimizing passive activities and ensuring they incorporate physical and intellectual activity in their daily lives."