New York, Feb 4 (IANS): Superagers - people who are aged 80 and above - have memories that are as sharp as those of healthy people, finds a research.

The team from Northwestern University's Feinberg School of Medicine found that brains of 80-year-old superagers look 30 years younger, revealing why the memories of these cognitively elite elders do not suffer the usual ravages of time.

"The brains of the superagers are either wired differently or have structural differences when compared to normal individuals of the same age," said Changiz Geula, research professor at the cognitive neurology and Alzheimer's disease centre at Northwestern University.

It may be one factor, such as expression of a specific gene, or a combination of factors that offers protection, he added.

The team found that superagers had nearly 90 percent fewer tangles linked to Alzheimer's.

Understanding their unique "brain signature" will enable scientists decipher the genetic or molecular source and may foster the development of strategies to protect the memories of normal ageing persons as well as treat dementia.

Their unusual brain signature has three common components when compared with normal persons of similar ages: a thicker region of the cortex; significantly fewer tangles (a primary marker of Alzheimer's disease) and a whopping supply of a specific neuron - von Economo -- linked to higher social intelligence.

"Identifying the factors that contribute to the Superagers' unusual memory capacity may allow us to offer strategies to help the growing population of 'normal' elderly maintain their cognitive function and guide future therapies to treat certain dementias," said Tamar Gefen, first study author.

The study was published in the Journal of Neuroscience.