Expert tells inquiry that other conditions such as depression can mimic the symptoms of dementia.

Almost a third of dementia diagnoses in Australia are incorrect, a medical expert has said.

A federal inquiry into early diagnosis and intervention for dementia has heard that 30 per cent of patients diagnosed with dementia are later found to be suffering from other conditions.

Dr Robert Prouse, from the Royal Australian College of Physicians, says other conditions such as depression can mimic the symptoms of dementia.

“There's a whole range of things that can present as cognitive decline that need to be tested along the way and that's where specialists come into it," Prouse told the inquiry in Sydney.

“It's probably common enough to say a third of patients improve, lose their depression and have a new outlook on life.”

He said he had also treated a number of patients who suffered from breathing problems during their sleep who had been able to move out of residential facilities and return to the community once their sleep apnoea had improved.

“We've had a number of people who have had significant cognitive decline,” Prouse said.

“By treating their sleep apnoea and improving nocturnal oxygenation, they've come back to normal.”

The inquiry by the House of Representatives Health and Ageing Committee is examining whether dementia should be made a National Health Priority Area due to its growing prevalence in communities.

Dementia in Australia is expected to triple by 2050.

AAP