Researchers say their findings hold promise for a saliva test that could predict the risk for Alzheimer's.
Lead author Shraddha Sapkota, PhD, a neuroscience graduate of the University of Alberta in Canada, and colleagues recently presented their findings at the 2015 Alzheimer's Association International Conference (AAIC).
Alzheimer's disease affects around 5.3 million people in the US and is the sixth leading cause of death in the country. It is predicted that by 2050, around 13.5 million Americans will have the condition.
At present, there is no single test to determine whether an individual has Alzheimer's or is at risk for the condition. An Alzheimer's diagnosis requires thorough medical evaluation, including physical and neurological examinations and mental status testing.
While there is currently no way to halt progression of Alzheimer's or reverse the disease, early diagnosis can increase a patient's likelihood of benefitting from medications that treat symptoms of the condition.
What is more, early detection of Alzheimer's can raise the likelihood of participation in clinical trials aimed at finding a cure for the disease.
However, Sapkota and colleagues note that many diagnostic methods for Alzheimer's can be invasive and costly, prompting the search for a simpler, cheaper technique.
Saliva 'has promising potential' for predicting, tracking cognitive decline
For their study, the research team used liquid chromatography-mass spectrometry (LCMS) to analyze the saliva samples of 22 participants with Alzheimer's, 25 participants with mild cognitive impairment (MCI) - a risk factor for Alzheimer's - and 35 participants with normal cognitive functioning.
The researchers identified compounds that were more pronounced in the saliva of participants with Alzheimer's and MCI, differentiating them from healthy participants. These findings were validated in a further sample including seven participants with Alzheimer's, 10 with MCI and 10 cognitively normal participants.
Further analysis revealed that higher levels of certain substances in participants' saliva were associated with poorer cognitive functioning. For example, a higher level of a certain compound in the saliva of participants with Alzheimer's was linked to slower information processing speed.
The team believes their findings hold promise for an inexpensive, noninvasive diagnostic technique for Alzheimer's, though they stress much more work needs to be done to determine just how effective such a test could be.
"Saliva is easily obtained, safe and affordable, and has promising potential for predicting and tracking cognitive decline, but we're in the very early stages of this work and much more research is needed.
Equally important is the possibility of using saliva to find targets for treatment to address the metabolic component of Alzheimer's, which is still not well understood. This study brings us closer to solving that mystery."
Protein in cerebrospinal fluid may predict decline from MCI to Alzheimer's
Another study presented at the AAIC revealed that cerebrospinal fluid (CSF) has shown promise for predicting the decline from MCI to Alzheimer's.
Conducted by Dr. Maartje Kester, of the VU University Medical Center in Amsterdam, and colleagues, the study included 162 participants with either MCI, Alzheimer's or normal cognitive functioning. All participants had two samples of CSF taken over a 2-year period.
The team found that participants with Alzheimer's had higher baseline levels of neurogranin - a protein expressed in the brain - in their CSF samples than participants with MCI and normal cognitive functioning.
What is more, baseline neurogranin levels were higher among participants whose MCI had progressed to Alzheimer's, indicating that the protein may be a predictor of cognitive decline among individuals with MCI.
The researchers also found that neurogranin levels increased over time among participants with normal cognitive functioning, but this was not the case for those with MCI or Alzheimer's.
"This may indicate that neurogranin levels in CSF reflect very early synaptic loss in Alzheimer's and may be useful for early detection," notes Dr. Kester, adding:
"We found that neurogranin is a potentially useful marker for the diagnosis, prognosis and monitoring of Alzheimer's."
Earlier this month, Medical News Today reported on a study by researchers from Washington University in St. Louis, which suggests midlife changes in CSF could be a predictor of Alzheimer's.
Published in JAMA Neurology, the study revealed that a fall in levels of a substance in CSF called beta-amyloid 42 was associated with the development of brain plaques later in life - a characteristic of Alzheimer's.