Unique urine smell test could lead to early Alzheimer’s diagnosis

A new non-invasive urine test could provide early diagnosis of Alzheimer’s disease, a new US study has revealed.

The research, published in the online journal, Scientific Reports could identify the disease that affects nearly 500,000 people living in the UK alone, before the physical symptoms of cognitive decline set in.

Researchers at the Monell Center at the US Department of Agriculture (USDA) and other collaborating institutions have revealed a unique odour signature was found to present in the urine of mice, before the development of Alzheimer’s related brain pathology deposits.

Dr Bruce Kimball is a chemical ecologist at the USDA National Wildlife Research Centre (NWRC) and is based at the Monell Centre. He commented: “Previous research from the USDA and Monell has focused on body odour changes due to exogenous sources such as viruses or vaccines. Now we have evidence that urinary odour signatures can be altered by changes in the brain characteristic of Alzheimer’s disease.

“This finding may also have implications for other neurologic diseases.”

Alzheimer’s disease is the most common type of dementia, affecting the cognitive ability of people living with it, causing the slow death of brain cells. Early signs are memory problems, though as its symptoms present themselves gradually, it can be difficult to identify.

The scientific breakthrough could see people being diagnosed early with Alzheimer’s though a non-invasive urine test.

Identifying early biomarkers for Alzheimer’s disease could allow doctors to diagnose patients with Alzheimer’s disease before brain decline and mental deterioration. This breakthrough could lead the way for upcoming treatments to slow the progression of the disease.

Co-author of the study and neurologist at the Case Western Reserve University School of Medicine, Daniel Wesson, said: “While this research is at the proof-of-concept stage, the identification of distinctive odour signatures may someday point the way to human biomarkers to identify Alzheimer’s at early stages.”

Researchers studied three mouse models, known as APP mice, which are designed to mimic Alzheimer’s-related brain pathology. They found that by using behaviour and chemical analysis, each strain of APP mice, produced urinary odour profiles, distinguishable from the controlled mice.

The change in odour was not caused by new chemical compounds, but a reflective shift in the concentrations of existing urinary compounds. Odour differences were also found in APP and control mice regardless of their age, and were found to proceed detectable amounts of plaque build-up in the brains of the APP mice.

The findings reveal that the unique odour signature is link to an underlying gene, as opposed to the development of pathological changes in the brain.

Researchers stressed that as Alzheimer’s is a uniquely human disease, further extensive studies would be required to identify Alzheimer’s related odour signatures in humans.

Commenting on the findings, director of research at Alzheimer’s Society, Doug Brown, said: “The findings of this study are interesting, but it is too early to tell if they can help us to develop ways to identify people with Alzheimer’s disease before memory symptoms appear. The test was carried out on genetically altered mice, which do not fully replicate several of the important changes seen in the brains of people with dementia, so we cannot yet predict that we will see the same urine changes in people.

“Dementia is the biggest health challenge facing us today, and timely diagnosis is critical to providing the best treatment and care. Although this is an interesting approach to the problem of identifying Alzheimer’s before memory symptoms appear, it is too early to tell whether this could be a valid way to diagnose the condition in people.”