Noel Faux and his team at Florey Institute of Neuroscience and Mental Health here tested iron levels in the blood of 1,100 volunteers.
The test conducted revealed that having Alzheimer's disease lowered blood hemoglobin levels and was a major risk factor for developing an untreatable form of anaemia, according to ABC news report.
"It's a little left field, so to speak, because when people think of Alzheimer's and dementia they think of the head, they think of the brain," Faux said.
"Recently, research has been moving into the blood, and a lot of that research is more around finding a marker that allows us to identify people who are at risk of developing Alzheimer's."
Faux said scientists do not fully understand what is causing the anaemia.
"We don't understand exactly what that relationship is, outside that there is a relationship. Our hypothesis is that the process of Alzheimer's manifesting within the red blood cells that will actually lead to the anaemia that we see."
He however hopes that the new discovery could help in improving lives of those with Alzheimer's after finding a treatment for the blood disorder.
"We're not trying to treat Alzheimer's, but we can give them better quality of life," he said.
"One of the other advantages of that is that it's known that people who have anaemia in old age tend to have a rate of decline in terms of cognition; their memory starts to drop off.
"So if we can sort of help alleviate the anaemia, then potentially the rate of decline of memory would slow - not be cured, but would potentially slow," he said.
"And that would be one of the benefits of actually trying to find treatment for this anaemia. Given that there is no cure for Alzheimer's, if we can improve quality of life for people with Alzheimer's - in this case, those who are anaemic - then it'll actually make life a little bit better," he said.