Tangle-free: On the left is a brain section from a super-aged individual showing very few of the fiber-like tangles. On the right is the same area of a normal elderly brain showing many more tangles.
Credit: Changiz Geula
NEW YORK: Some people maintain amazingly sharp memory despite old age, and now researchers have the first clues why.
These people might, for example, have the memory of an average 50-year-old at the age of 80, and possess what is known as a 'super-aged' brain.
According to a new study, the brains of these people have fewer fibre-like tangles of a particular type of central nervous system protein than their peers, possibly explaining their superior mental agility.
Tangles are key
These so-called tau proteins help neurones communicate with one another and help transport nutrients and waste, but accumulation of tangles of them with age is thought to slowly kill brain cells. Other studies have also linked the tangles to Alzheimer's disease.
"It was always assumed that the accumulation of these tangles is a progressive phenomenon through the ageing process," said Changiz Geula, a neurologist at Northwestern University in Chicago, USA. "But we are seeing that some individuals are immune to tangle formation and that the presence of these tangles seems to influence cognitive performance."
Geula presented the findings last week at the annual meeting of the American Society for Neuroscience, held in Washington DC.
Critical in memory
To make the discovery, Geula counted the fibre tangles in the brains of five deceased super-aged patients, and compared them to the brains of normal elderly patients. He found that the super-aged group had far fewer tangles than the control group, and that both groups had fewer tangles than a typical Alzheimer's patient.
Both the super-aged and control groups had similar levels of amyloid plaque, which is also associated with Alzheimer's, he said, indicating that the tangles may be the critical factor for maintaining good memory.
According to Geula, while the connection between tangles and Alzheimer's has been previously studied, this is the first time a link between the tangles and cognition in elderly patients has been investigated.
While the findings may help further research on Alzheimer's and dementia, the study is also "significant for the millions of normal elderly" because it "may help to preserve and perhaps also improve cognitive performance as they age," said Geula.
Important clues
The next step is to increase the number of patients enrolled in the study to explore epidemiological factors such as diet, exercise, disease and education. Other future research will include genetic and brain imaging, as well as examination of the chemistry, anatomy and pathology of the brains, Geula said.
According to Yaakov Stern, a neuropsychologist who researches Alzheimer's at Columbia University in New York City, the new study could provide some important clues in understanding how our brains age.
"The cause of cognitive decline in non-demented elders is still not fully understood," he said. "The observation that tangles can contribute to this decline is of interest."
