The results of a small study has suggested that it might be possible to develop a saliva test for dementia. The scientists were based at the US-based Beaumont Research Institute and Oakland University William Beaumont School of Medicine and the Canadian University of Alberta. The study was published in the Journal of Alzheimer’s Disease which is a peer-reviewed journal and is available to read online.
The most common form of dementia is Alzheimer’s Disease, which is a progressive neurological disorder. It can affect different functions of the brain, most particularly memory. The symptoms develop slowly and some cases of Alzheimer’s can also be affected by vascular dementia. Symptoms include disorientation and confusion, getting lost in a familiar place, language problems, decision-making problems, mobility problems, self-care problems, anxiety, hallucinations or delusions and personality changes. Age is a big risk factor for the disease, and it is estimated that up to one in fourteen people over 65 years and one in every six people over 80 could develop dementia. It is caused by the build-up of amyloid plaques, which are abnormal deposits of proteins or neurofibrillary tangles in the brain. There can also be an imbalance of acetylcholine, a chemical. These can gradually reduce and destroy healthy neurons which are the nerve cells carrying signals to the brain. Memory cells are often the first affected.
This proof-of-concept study examined whether saliva contained substances that could be used to decide whether a person had mild cognitive impairment or Alzheimer’s Disease. The scientists recruited 12 healthy adults, 9 adults with Alzheimer’s and 8 who had been diagnosed with mild cognitive impairment which can be a precursor to dementia. The participants had been recruited from a centre which specialised in care for the elderly. The patients’ diagnoses had been made through the use of brain function assessments, which were normally used to assess whether a person might be developing mild cognitive dysfunction or another form of dementia. These tests included the Geriatric Depression Scale, the Clinical Dementia Rating Scale and the Mini-Mental State Examination.
Nuclear magnetic resonance spectroscopy was used to analyse the samples of saliva. This enabled the scientists to measure biomarker levels. The scientists found that it was possible to distinguish between the different groups of people when looking at patterns of biomarkers in the saliva. People with mild cognitive impairment showed high levels of acetone and imidazole and low levels of galactose when compared to healthy adults with no sign of cognitive impairment. People with Alzheimer’s showed high levels of creatinine and 5-aminopentanoate when compared with people who had been diagnosed with mild cognitive impairment.
The study was a pre-trial to see whether it might be worth carrying out a larger trial of the method. The scientists felt that they would want to carry out a bigger trial, as it is relatively unobtrusive to collect saliva samples. The scientists estimated that they would need at least 100 people per group to offer a way to reliably detect biomarker differences between the different groups.
The scientists noted that there was no way to diagnose Alzheimer’s Disease as it can currently only be diagnosed using cognitive assessments. Results of brain imaging and the medical history of the people concerned were unknown, so it is possible that some of the people may have had vascular dementia. Finding a biomarker would be useful, but there would still be some studying to be done to determine who to screen and whether the test would be more beneficial than the current clinical assessment methods.
People with mild to moderate dementia can be prescribed drugs to help, but there is no cure for the condition. Diagnosing the symptoms earlier can help people to get support for their condition. Future drugs may be able to target the disease more effectively.
People who are concerned about their memory should visit their GP so that they will be able to access support and help if it is required. Cognitive problems can be caused by a number of different things, so it is best to receive a proper diagnosis.
Yilmaz A, Tim G, Han B, et al. Diagnostic Biomarkers of Alzheimer's Disease as Identified in Saliva using 1H NMR-Based Metabolomics. Journal of Alzheimer's Disease. May 2017