Elderly individuals who lose the ability to tell when somebody is being untruthful, insincere or sarcastic may be showing an early sign of a neurodegenerative disease, such as dementia, researchers from the University of San Francisco explained at the 63rd Annual Meeting of the American Academy of Neurology in Hawaii. The presentation was called “Divergent Neuroanatomic Correlates of Sarcasm and Lie Comprehension in Neurodegenerative Disease.”

In this study, the researchers asked several seniors, some with neurodegenerative diseases and others without to analyze videos of some people talking frankly or deceitfully. They say they have been able to determine what parts of the brain give us the ability to identify lies and sarcasm.

The scientists mapped the participants’ brains using MRI (magnetic resonance imaging). These scans showed links between deteriorations in specific parts of the brain and an individual’s inability to spot insincerity.

Neuropsychologist Katherine Rankin, PhD, said:

“These patients cannot detect lies. This fact can help them be diagnosed earlier.”

Co-presenter Tal Shany-Ur, PhD, explained that their findings may help health care professionals and caregivers identify individuals with neurodegenerative diseases earlier on if their inability to detect lies is noticed.

Neurodegenerative diseases occur after the progressive loss of function or structure of neurons, including the death of neurons. Examples include Alzheimer disease, Parkinson disease and Parkinsonian Syndromes, Lewy body dementia, Vascular dementia, Progressive supranuclear palsy, and Amyotrophic Lateral Sclerosis. Put simply: the nervous system progressively and irreversibly degenerates.

Rankin said that these people have to be identified early. Early detection and diagnosis provides the best chance for intervention when drugs become available.

This study forms part of a larger work by the Memory and Aging Center, University of California, San Francisco, which is looking into emotion and social behavior in neurodegenerative diseases in order to improve prevention, prediction and diagnosis.