Scans show Huntington's toll on brain

Australian researchers are using new imaging technology to provide an insight into the degenerative effect of Huntington's disease on the brain.

Doctoral student India Bohanna, from the Howard Florey Institute in Melbourne, used diffusion magnetic resonance imaging technology to track the breakdown in structural connections within the brain. The research was presented at the Organization for Human Brain Mapping conference being held this week in Melbourne.

Bohanna said she and her collaborators at Monash University found extensive white matter degeneration in patients recently diagnosed with Huntington's disease.

The researchers used diffusion MRI, which maps the brain's white matter tracts by measuring the movement of water molecules in the tissues. White matter tracts are the connections between brain regions that allow one region to communicate with another.

Bohanna said a breakdown in these structural connections disrupts the brain's communication. This could explain the motor and cognitive problems such as memory loss and clumsiness that appear as early symptoms of the onset of Huntington's disease.

Inherited genes

Huntington's disease affects about seven in every 100,000 Australians, with children of a parent with the disease having a 50-50 chance of inheriting the genes that cause it.

Symptoms usually become apparent around middle age, with death occurring 15 to 20 years later. But Bohanna said it was recently discovered that white matter degeneration started before patients were officially diagnosed with Huntington's disease. The extent of the degeneration was unknown, and her research had filled this gap.

She said they also found a startling correlation between the severity of the loss of motor function and loss of white matter tracts.

"The degeneration in white matter tracts gets worse as people's symptoms get worse," she said.

Bohanna and her team are working with patients who have early-onset symptoms of Huntington's disease. They have now received funding from the CHDI foundation to examine white matter degeneration in people who are gene-positive to Huntington's disease, but are up to 10 years from developing symptoms.

"Currently the effectiveness of new treatment is determined by its ability to reduce symptoms," Bohanna said.

"Our discovery could allow researchers to test therapies even before symptoms appear."

Collaborator associate professor Anthony Hanna, also of the Howard Florey Institute, has published work that shows mental and physical exercise can delay and slow the progression of Huntington's disease in mice.