Queensland researchers say they have made a breakthrough in their quest to find a way to treat Alzheimer's disease and restore memory.

Scientists at the Queensland Brain Institute in St Lucia have had success in using non-invasive ultrasound technology to treat the disease in trials involving mice.

About 250,000 Australians have either dementia or Alzheimer's.

The drug-free approach breaks apart the neurotoxic amyloid plaques that result in memory loss and cognitive decline.

It could fundamentally change the understanding of how to treat Alzheimer's, researcher director Professor Jurgen Gotz said.