Elevated levels of formic acid in the urine have been shown to be an early sign of Alzheimer's disease.

The level of formic acid in the urine increases at the earliest stages of cognitive impairment and may be one of the first predictors of Alzheimer's disease. The scientists also found that knowledge of formic acid and formaldehyde levels, in addition to plasma biomarkers, improves the accuracy of disease staging, and suggest using urine testing for formic acid for mass population screening.