A new international study led by University of Sydney has found that medication use increases in newly diagnosed dementia patients, particularly unnecessary or inappropriate medications.

Published today in Journals of Gerontology: Medical Sciences, the longitudinal study of nearly 2,500 people was conducted in collaboration with Yale University and University of Kentucky.

The number of people living with dementia around the world is 50 million and in Australia is currently 425,000. This has significant cost implications for healthcare systems with recent estimates suggesting that dementia will cost Australia more than $15 billion per year. Dementia is currently the second leading cause of death in Australia.

"Our study found that following a diagnosis of dementia in older people, medication use increased by 11 per cent in a year and the use of potentially inappropriate medications increased by 17 per cent," said lead author Dr Danijela Gnjidic, NHMRC Dementia Leadership Fellow and Senior Lecturer from the Faculty of Pharmacy and Charles Perkins Centre at University of Sydney.

Potentially inappropriate or unnecessary medications included sleeping tablets, pain drugs, depression drugs and acid reflux drugs (proton pump inhibitors).

"These medications are typically recommended for short term use but are commonly used long term by people with dementia," she said.

"A number of reasons may account for this, including inadequate guidelines, lack of time during physician patient encounters, diminished decision-making capacity, difficulties with comprehension and communication, and difficulties in establishing goals of care.

"These findings are of major concern and highlight the importance of weighing up the harms and benefits of taking potentially unnecessary medications as they may lead to increased risk of side effects such as sedation or drowsiness, and adverse drug events such as falls, fractures and hospitalisation.

"Further efforts are clearly needed to support better recognition of potentially inappropriate medications to minimise possible harms and warrants interventions to minimise such prescribing.

"For Australians living with dementia and their caregivers (who commonly are responsible for managing medications for people with dementia), the key is to communicate closely with general practitioners, pharmacists and other health professionals to make informed decisions and to practice good medicine management techniques to minimise the risk of side effects.

"Deprescribing unnecessary medications may improve an individual's quality of life and can reduce unnecessary healthcare cost."