The odour signature appears in urine before significant development of Alzheimer-related brain pathology. (Representational Image)
In what could lead to a non-invasive tool for early diagnosis of Alzheimer's disease, researchers have identified an odour biomarker that can be used to predict the development of the debilitating brain disorder.
The odour signature appears in urine before significant development of Alzheimer-related brain pathology, the study said.
"We have evidence that urinary odour signatures can be altered by changes in the brain characteristic of Alzheimer's disease," said one of the study authors Bruce Kimball from the US Department of Agriculture (USDA).
The odour signature was identified in mouse models of Alzheimer's disease.
Because Alzheimer's is a uniquely human disease, scientists create models of associated brain pathology to study the disease in mice.
One of the hallmark pathological indicators of Alzheimer's disease is an excess formation of amyloid plaque deposits in the brain.
In the study, published online in the journal Scientific Reports, researchers studied three separate mouse models, known as APP mice, which mimic Alzheimer's-related brain pathology.
Using both behavioural and chemical analyses, the researchers found that each strain of APP mice produced urinary odour profiles that could be distinguished from those of control mice.
The odour differences between APP and control mice were mostly independent of age and preceded detectable amounts of plaque build-up in the brains.
"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," Daniel Wesson, neuroscientist at the Case Western Reserve University School of Medicine in the US, said.