Investigators found that levels of formic acid, a metabolic product of formaldehyde found in urine, were significantly higher in individuals with Alzheimer disease including those with subjective cognitive decline, which may indicate very early stages of the disorder. Urinary formic acid and formaldehyde are likely to be new biomarkers independent of the existing AD diagnostic criteria. Researchers also compared formic acid and formaldehyde levels across different AD stages and found significantly higher levels across all stages compared with people who had no cognitive decline. Levels were also higher in patients with AD than in patients with MCI and those with cognitive impairment and no MCI, as well as in those with poorer neurologic test scores.