The body, the brain and Huntington's disease

Scientists at Melbourne's Howard Florey Institute have shown that physical exercise alone can delay onset of memory loss in Huntington's disease (HD), but a combination of mental and physical exercise is more beneficial in delaying the fatal genetic disease's symptoms.

Dr Anthony Hannan's nature-versus-nurture studies have previously shown that a combination of mental and physical exercise could delay the onset and progression of HD. Now he has looked at whether exercise alone is responsible for these dramatic effects.

"The combination of mental and physical exercise requires a greater range of movements and fine co-ordination, which is more challenging than simply running on a mouse wheel," Hannan said.

"Unlike our other studies, these HD mice were only given running wheels to enhance physical activity, compared to previous studies where mice had a range of mazes, toys and exercise equipment to stimulate them both mentally and physically.

"This study has allowed us to compare data with our previous work to prove that to effectively delay the onset and progression of HD, a combination of physical and mental stimulation is essential.

"Surprisingly, we found in this latest study that physically active HD mice had the same level of memory restoration as HD mice used in a previous experiment to test the effects of fluoxetine (an anti-depressant commonly marketed as Prozac).

"If we can develop a drug that creates the same reaction in the brain that occurs with mental and physical stimulation, this could lead to a radical treatment for HD patients.

"Due to its well-defined genetics and range of symptoms, Huntington's disease is a very powerful model for setting up paradigms in the nature-versus-nurture area.

"Our research has therapeutic implications for other devastating and difficult to treat neurodegenerative disorders, like Alzheimer's disease and related forms of dementia.

"Treatments for complex psychiatric disorders, like depression and schizophrenia, may also benefit from our efforts to understand how genes and environment combine in brain disorders."

Huntington's disease is characterised by degeneration of significant areas of the brain, producing motor, cognitive and psychiatric symptoms. It was previously thought that onset and progression of the disease was 100 per cent genetically determined and could not be delayed, but Hannan's research has proven this theory incorrect.

There is no cure for HD and death usually results within 10 to 20 years of symptom onset. The disease can be detected by genetic testing and it is caused by a mutation in a single gene and this defective gene is passed from affected parents to 50 percent of their children, who will inherit the disorder.

For this study Hannan's team included Terence Pang, Nathan Stam, Jess Nithianantharajah and Monique Howard. Their work was recently published in the international journals Neuroscience and Nature Reviews Neuroscience.

Source: Howard Florey Institute