A rise in the number of younger people being diagnosed with dementia is the subject of an examination to be conducted by Sydney researchers. It’s the first such research study in Australia.

Professor Brian Draper from the school of psychiatry at the University of NSW says as many as one in 750 Australians may be affected by younger onset dementia before the age of 65.

International data had previously put that number at around one in 1000 people.

Dr Adrienne Withall - the Chief Investigator of the INSPIRED (Improving Service Provision for Early Onset Dementia) Study said that younger onset dementia is characterised by changes in memory, thinking and behaviour.

People often report that they struggle to "find" words, forget the meaning of objects or can't keep up with a story and become increasingly frustrated and agitated she said.

According to Professor Draper, this increase is at least partially because of the high number baby boomers who are moving through the population.

Younger onset dementia in those aged 48-65 is of increasing public concern he said, because more people were being diagnosed but their needs were not being met by existing services, which are geared more towards aged care.

Those patients had a range of illnesses including Alzheimer's disease, frontotemporal dementia, brain infections, Parkinson's disease and multiple sclerosis.

Preliminary research identified 141 people in the eastern suburbs of Sydney alone with younger onset dementia.