Maybe you have an 85-year-old grandfather who still whips through the newspaper crossword puzzle every morning or a 94-year-old aunt who never forgets a name or a face. They don't seem to suffer the ravages of memory that beset most people as they age. Researchers at Northwestern University's Feinberg School of Medicine wondered if the brains of the elderly with still laser sharp memory -- called "super aged" -- were somehow different than everyone else's. So, instead of the usual approach in which scientists explore what goes wrong in a brain when older people lose their memory, they investigated what goes right in an aging brain that stays nimble.

Now they have a preliminary answer. Scientists examined the brains of five deceased people considered super aged because of their high performance on memory tests when they were more than 80 years old and compared them to the brains of elderly, non-demented individuals. Researchers found the super aged brains had many fewer fiber-like tangles than the brains of those who had aged normally. The tangles consist of a protein called tau that accumulates inside brain cells and is thought to eventually kill the cells. Tangles are found in moderate numbers in the brains of elderly and increase substantially in the brains of Alzheimer's disease patients.

"This new finding in super aged brains is very exciting," said Changiz Geula, principal investigator of the study and a research professor of neurology at the Cognitive Neurology and Alzheimer's Disease Center at Northwestern's Feinberg School. "It was always assumed that the accumulation of these tangles is a progressive phenomenon through the aging process. But we are seeing that some individuals are immune to tangle formation and that the presence of these tangles seems to influence cognitive performance." Individuals who have few tangles perform at superior levels, while those who have more tangles appear to be normal for their age, Geula noted. Geula will present his findings Sunday, November 16, at the Society for Neuroscience annual meeting in Washington, D.C.

The number of plaques in the brains of the super aged was similar to that in the brains of the normally aging group. The plaque is an aggregation of protein called amyloid that becomes deposited outside the brain cell and disrupts communication between neurons. Like tangles, plaques also are found in modest numbers in the brains of aged individuals and show a dramatic increase in number in Alzheimer's disease. Geula said the lower number of tangles in the super aged appears to be the critical difference in maintaining memory skills.

Some of the super aged in the study performed memory tasks at the level of people who were about 50 years old. For example, after being told a story, they were able to remember it immediately after and still accurately recall its details 30 minutes later. They also remembered a list of 15 words and recalled these words equally well when tested after 30 minutes.

Geula said new research will focus on what makes cells in super aged brains more resistant to tangle formation. "We want to see what protects the brains of these individuals against the ravages that cause memory loss," he said. " Understanding the specific genetic and molecular characteristics of the brains that makes them resistant, someday may lead to the ability to protect average brains from memory loss. "

Geula's research is part of a larger super aging study at Northwestern's Cognitive Neurology and Alzheimer's Disease Center (CNADC). The study's goal is to identify high functioning individuals over 80 and investigate what factors are important to maintain this ability into old age. A number of super aged individuals have been identified and are being followed up annually with tests of cognitive abilities. Recruitment continues for the study.

A neural link between intelligence and self-control

If you had a choice between receiving $1,000 right now or $4,000 ten years from now, which would you pick? Psychologists use the term "delay discounting" to describe our inability to resist the temptation of a smaller immediate reward in lieu of receiving a larger reward at a later date. Discounting future rewards too much is a form of impulsivity, and an important way in which we can neglect to exert self-control.

Previous research suggests that higher intelligence is related to better self-control, but the reasons for this link are unknown. Psychologists Noah A. Shamosh and Jeremy R. Gray, from Yale University, and their colleagues, were interested in testing the idea that certain brain regions supporting short-term memory play a critical role in this relationship. "It has been known for some time that intelligence and self-control are related, but we didn't know why. Our study implicates the function of a specific brain structure, the anterior prefrontal cortex, which is one of the last brain structures to fully mature," said Dr. Shamosh.

In this study, 103 healthy adults were presented with a delay discounting task to assess self-control: a series of hypothetical choices where they had to choose between two financial rewards, a smaller one which they would receive immediately or another, larger reward which would be received at a later time. The participants then underwent a variety of tests of intelligence and short term memory. On another day, subjects' brain activity was measured using fMRI, while they performed additional short-term memory tasks.

The results show that participants with the greatest activation in the brain region known as the anterior prefrontal cortex also scored the highest on intelligence tests and exhibited the best self-control during the financial reward test. This was the only brain region to show this relation. The results appear in the September issue of Psychological Science, a journal of the Association for Psychological Science.

Previous studies have shown that the anterior prefrontal cortex plays a role in integrating a variety of information. The authors suggest that greater activity in the anterior prefrontal cortex helps people not only to manage complex problems, resulting in higher intelligence, but also aids in dealing with simultaneous goals, leading to better self-control.

Knowledge of the neural mechanisms underlying the relationship between short term memory, intelligence and delay discounting may result in improved techniques of increasing self-control. This is particularly applicable in regulating behavior related to gambling and substance abuse. "Understanding the factors that support better self-control is relevant to a host of important behaviors, ranging from saving for retirement to maintaining physical and mental health," the authors conclude.