Unable to perceive lies, sarcasm? It's a warning sign of dementia

According to experts, the identification of these signs may hold the key to producing new tailor-made drugs and preventive strategies to treat the age-related mental decline.

Lead researcher, Katherine Rankin, a neuropsychologist at the University of California, San Francisco stated, "If somebody has strange behavior and they stop understanding things like sarcasm and lies, they should see a specialist who can make sure this is not the start of one of these diseases.”

175 people examined for dementia
In a bid to determine whether the failure to discern insincerity or deception actually paves the way for dementia, the researchers studied 175 people.

Though healthy people had no problem identifying lies and deception, the study found the elderly with frontotemporal dementia were blind to sarcasm, lies and truth.

Some of the subjects were healthy but over half of them were afflicted with neurodegenerative diseases that cause certain parts of the brain to deteriorate and unable to process thoughts intelligently.

As a part of the study, the volunteers were asked to view video tapes of two people talking. Their conversation was peppered with sarcasm and occasional lies, a fact quite evident in the clipping from verbal and non verbal cues.

The study subjects were then asked yes or no questions about what they had seen.

Using magnetic resonance imaging (MRI) the researchers also scanned the participants’ brains to find a link between the inability to detect deception and dementia.

Outcome of the study
Though healthy people had no problem identifying lies and deception, the study found the elderly with frontotemporal dementia were blind to sarcasm, lies and truth.

However, those with other types of dementia, including Alzheimer's, fared considerably better in the lie-detecting task.

Rankin explained, "We want to find these people early. We want people to recognize that these social lapses are actually a disease -- parts of their brain are being eaten away."

The results of the study were presented at the annual meeting of the American Academy of Neurology in Honolulu.

About dementia
Dementia is a chronic and progressive age-related disease characterized by irreversible cognitive decline and functional impairment.

The mental disorder can be caused by diseases such as Alzheimer's and Parkinson's, as well as stroke and infections to the brain.
Though it is believed that genetics play a role in dementia, recent studies reveal that lifestyle factors might also influence the severity of the problems.

The disease currently affects over 24 million people worldwide.

Alzheimer's is the third-largest killer in the United States after heart disease and cancer. The direct and indirect cost of Alzheimer care is over $100 billion in the United States alone.