A simple cheap urine test can diagnose Alzheimer's years before symptoms develop, according to new research. The first signs of the disease have been detected through a chemical - in wee, say scientists.
Drugs fail to halt the condition because they are administered too late - once memory loss and confusion has already taken hold. The finding could lead to older people being routinely screened by their GP, with vulnerable patients prescribed medications when they are more likely to work.
It was based on a study of 574 individuals with various levels of cognitive decline. Those with dementia had increasing amounts of the organic compound formic acid. Corresponding author Dr Qihao Guo, of Shanghai Jiao Tong University Affiliated Sixth People's Hospital, said: "Alzheimer's is a continuous and concealed chronic disease. It can develop and last for many years before obvious cognitive impairment emerges.
"The early stages occur before the irreversible dementia stage, and this is the golden window for intervention and treatment. Therefore, large-scale screening for early-stage Alzheimer's disease is necessary for the elderly."
Currently, PET (positron emission tomography) scans are required for clinical diagnosis of dementia or painful spinal lumbar punctures. Both are costly. The study in Frontiers offers hope of an inexpensive and convenient alternative. It is the first to identify formic acid as a sensitive urinary biomarker.
Participants included patients with different levels of disease severity - ranging from mild cognitive impairment (MCI) to fully-fledged disease. Analysis showed quantities were significantly raised in all Alzheimer's groups including those in the primary stages - compared to peers with normal mental powers.
Dr Guo said: "This suggests formic acid could act as a sensitive biomarker for the very early stages of Alzheimer's disease." Current methods are inappropriate for routine screening - meaning most patients only receive a diagnosis when it is too late for effective treatment.
A non-invasive, inexpensive, and convenient urine test for formic acid could be "just what the doctor ordered", explained the Chinese team. Other urinary biomarkers for Alzheimer's have been unsuitable to reveal the early stages of the disease, leaving the 'golden window' elusive.
They include formaldehyde. Formic acid is a metabolic by-product - and a better bet, said Dr Guo. The researchers collected urine and blood samples and performed psychological evaluations.
Interestingly, combining urinary formic acid levels in combination with blood-based Alzheimer's biomarkers was even more accurate. It predicted what stage of the disease a patient was experiencing. Further work is needed to understand the link between Alzheimer's and formic acid.
Dr Guo said: "Urinary formic acid showed an excellent sensitivity for early Alzheimer's screening. The detection of urine biomarkers of Alzheimer's is convenient and cost-effective, and it should be performed during routine physical examinations of the elderly."
Alzheimer's and other forms of dementia affect over 920,000 Britons, a figure that will reach two million by 2050. Worldwide, cases will triple beyond 150 million.
