Drug companies have moved too soon in abandoning efforts to create an Alzheimer's wonder drug, scientists say.
With drug trials costing up to $1 billion and no guarantee of success, companies are increasingly opting for simpler projects with more chance of yielding a financial windfall, they say.
Companies have significantly disinvested in the complex field of neuroscience but the cuts come despite continued inroads in Alzheimer's research, the scientists say.
The head researcher in neural plasticity and regeneration at the Garvan Institute, Bryce Vissel, said drug companies were too quick to give up on trials to develop a drug to cure or better manage Alzheimer's disease.
Dr Vissel acknowledged that therapies based on the current hypothesis of the cause of Alzheimer's - too much of a particular protein in the brain - had failed in trials.
But he said the failures meant researchers were edging closer to a breakthrough.
"While (failure) is extremely disappointing and has certainly been very expensive, it's important to note that it's the nature of science that we have to go through experiments and we have to gain experience to understand disease and understand therapeutic strategies," he said.
Dr Vissel said researchers analysing the failed trial data have found cause for optimism.
"Some analysis of those (failed trials) have suggested there may be some way that we can pull information out of those trials and see that there may be some hint that something is showing the potential for benefit," he said.
"We probably shouldn't be giving up at this point."
A senior lecturer in pharmacology at the University of Adelaide, Ian Musgrave, said several major drug companies were also being squeezed by the pending expiration of profitable patents.
"They're going to need guaranteed winners to return that income stream and things like Alzheimer's disease, despite the fantastic progress we're making and the really exciting (research) results that are coming out, some of these (companies) are not seeing Alzheimer's disease as something to bet on," he said.
Dr Musgrave said some scientists believe the brain of an Alzheimer's sufferer begins to change about 25 years before symptoms begin to show.
If that theory holds, that could mean that trials, which were typically conducted on people battling symptoms, need to be overhauled.
"If this disease is beginning 25 years before we see overt symptoms then by the time we are starting a lot of these trials ... it may be all but impossible to reverse," he told a media briefing on Monday.
About 300,000 Australians suffer from dementia, the most common form of which is Alzheimer's, costing the economy $5 billion per year in health and aged-care costs.
There are four drugs on the market to help sufferers manage Alzheimer's.
Some drug companies are continuing to run Alzheimer's trials with two more soon to start in Australia.