Detecting dementia early

Saliva may hold clues to diagnosing and treating Alzheimer's disease

December 8, 2015

When are lapses in memory just a normal part of aging, and when are they a sign of something more serious?

It's a question that concerns a growing number of older Canadians and their loved ones. In 2011, 747,000 Canadians aged 65 and older – nearly 15% of the population – were living with Alzheimer's disease and other dementias. According to the Alzheimer Society of Canada, that figure could increase to 1.4 million by 2031.

For years, researchers have tried to find a simple way to diagnose Alzheimer's and to develop drugs to treat the disease. One of the main stumbling blocks has been the lack of so-called biomarkers – chemicals inside the body that can be used to detect the presence of a disease, or measure its severity. Some scientists have tried detecting changes in brain function by studying blood or urine samples, but so far they have not been able to identify a reliable biomarker.

In Canada, the Canadian Consortium on Neurodegeneration in Aging (CCNA) is a hub for all aspects of research on diseases that affect brain function in aging, including Alzheimer's disease. Supported by the Canadian Institutes of Health Research and other partners, CCNA researchers pursue bold ideas to improve the quality of life and the quality of services for those living with dementia, as well as their caregivers.

At the University of Alberta, CCNA member Dr. Liang Li has been looking for clues to Alzheimer's in saliva. He believes the disease alters our metabolism — all of the chemical processes that take place in the body. These changes, in turn, create small molecules that can be seen by highly sophisticated equipment.

"If we can identify these changes, it can help us diagnose the disease in its early stages," said Dr Li.

Earlier diagnosis means patients can get support and information about possible treatments and lifestyle changes that may slow down the disease. It also gives patients more time to make key financial and care decisions for the future.

Working with Dr. Roger Dixon in the university's Psychology department, Dr. Li has analyzed saliva samples from older adults with Alzheimer's disease, mild cognitive impairment (MCI) and normal cognition. He has discovered two changes in adults with MCI, which is sometimes a precursor to more severe forms of dementia. First, these patients have less taurine, a naturally occurring compound believed to protect the brain against neurodegenerative diseases, such as Alzheimer's. Second, these patients have more dipeptides, molecules that are produced when proteins in the body begin to break down.

Dr. Li's team is now building on these findings, and trying to identify other small molecules that are altered during the progression of MCI to the more serious Alzheimer's disease. Ultimately, they hope that their discoveries will lead to a simple test that will enable doctors to diagnose both MCI and Alzheimer's disease before patients begin to experience symptoms.

There are many memory loss conditions, including dementia and Alzheimer's that share characteristics.  Some of these conditions are very treatable — and even reversible. Early detection means early intervention which often leads to better outcomes.

Empowering patients and their family members with knowledge helps them to better manage the practical aspects of the disease, like accessing support services and planning for their future.

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