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February 3, 2011

Research Notes

Aerobics pump up seniors’ memory centers

A new study shows that a year of moderate physical exercise can increase the size of the brain’s hippocampus in older adults, leading to an improvement in spatial memory.

The project — conducted by researchers at Pitt, the University of Illinois, Rice University and Ohio State University — is considered the first study of its kind focusing on older adults who already are experiencing atrophy of the hippocampus, the brain structure involved in all forms of memory formation.

The study, funded through the National Institute on Aging, appeared in the Jan. 31 Proceedings of the National Academy of Sciences.

Researchers divided 120 sedentary older people without dementia into two exercise groups. One group walked around a track for 40 minutes a day, three days a week; the other group did stretching and toning exercises.

Magnetic resonance imaging and spatial memory tests were conducted before the intervention, after six months and at the end of the one-year study.

The aerobic exercise group showed an increase in volume of the left and right hippocampus of 2.12 percent and 1.97 percent, respectively. The same regions of the brain in those who did stretching exercises decreased in volume by 1.40 and 1.43 percent.

The aerobic exercise group also showed improved memory function, an improvement associated with the increased size of the hippocampus.

The authors also examined several biomarkers associated with brain health, including brain-derived neurotrophic factor (BDNF), a small molecule that is involved in learning and memory. They found that the increases in hippocampal size were associated with increased amounts of BDNF.

“We think of the atrophy of the hippocampus in later life as almost inevitable,” said Pitt psychology faculty member Kirk Erickson, the paper’s lead author. “But we’ve shown that even moderate exercise for one year can increase the size of that structure. The brain at that stage remains modifiable.”

SHRS faculty awarded NIH grants

Several faculty members in the School of Health and Rehabilitation Sciences recently were awarded National Institutes of Health research grants.

SHRS announced NIH grants to the following faculty members in the Department of Communication Science and Disorders:

Connie Tompkins, to study behavioral treatment for adults who have damage to the right side of the brain and who have difficulty understanding conversations;

Kittie Verdolini, to study voice problems in teachers and treatment of vocal fold nodules in children, and

Sheila Pratt and John Durrant, to develop a head tracking and orientation procedure for the automated assessment of hearing in infants and toddlers.

Teen brain explained?

Neuroscience researchers have recorded neuron activity in adolescent rat brains that could reveal the biological root of the teenage propensity to consider rewards over consequences and explain why adolescents are more vulnerable to drug addiction, behavioral disorders and other psychological ills.

The team reported in the Journal of Neuroscience that electrode recordings of adult and adolescent rat brain-cell activity during the performance of a reward-driven task show that adolescent rat brains react to rewards with far greater excitement than adult brains.

This frenzy of stimulation occurred with varying intensity throughout the study along with a greater degree of disorganization in adolescent rat brains. The brains of adult rats, on the other hand, processed their prizes with a consistent balance of excitation and inhibition.

Adult and adolescent rats — which exhibit behavioral and biological similarities to adult and teenage humans — were presented with three holes to poke their noses through and received a sugar pellet when they chose the center hole.

Brain activity in the adolescents was similar to that of the adults most of the time but striking differences arose when the younger rats retrieved rewards. As each of the adult rats collected a sugar pellet, the orbitofrontal cortex neurons showed the normal increase in both excitation and inhibition, with consistent levels of each impulse throughout the study.

Adolescents, on the other hand, exhibited surges of excitation that ranged from twice to four times the levels in adults. At the same time, the inhibitory impulses in the adolescents’ brains barely changed from the low levels they experienced before receiving the sugar pellet.

The extreme difference in brain activity provides a possible physiological explanation as to why teenagers are more prone than adults to rash behavior, addiction and mental diseases, said lead researcher Bita Moghaddam, a faculty member in neuroscience. She and co-author David Sturman, a neuroscience doctoral student, observed the disparate reactions to reward in individual neurons in the orbitofrontal cortex, a brain region that weighs payoff and punishment to plan and make decisions.

“The disorganized and excess excitatory activity we saw in this part of the brain means that reward and other stimuli are processed differently by adolescents,” Moghaddam said. “This could intensify the effect of reward on decision making and answer several questions regarding adolescent behavior, from their greater susceptibility to substance abuse to their more extreme reactions to pleasurable and upsetting experiences.”

In addition, malfunctions in the orbitofrontal cortex have been observed in cases of schizophrenia, mood disorders and other psychological disturbances, Moghaddam said. The type of erratic activity in the cortex that she and Sturman observed could aggravate these conditions at a time when the maturing brain is vulnerable.

“The symptoms of these illnesses generally begin to appear during adolescence,” Moghaddam said. “Adolescence is a period of behavioral and psychiatric vulnerabilities, so the disorganized brain activity and excess excitation could push a brain already predisposed to mental disorders too far, triggering the onset of symptoms.”

Antimicrobial research funded

Ian Nettleship, a faculty member in mechanical engineering and materials science in the Swanson School of Engineering, has received a $197,653 grant from the National Science Foundation for “Nanoparticle Control of Microbial Development on Ceramic Surfaces.”

Nettleship and co-investigator Anil Ojha of the Department of Microbiology and Infectious Diseases in the Graduate School of Public Health will study the effect of silver nanoparticles on the attachment of bacteria to the surfaces of ceramics used in water filters and medical devices in order to develop ceramic materials that are resistant to biofilm formation and fouling.

The study also will provide technical help to organizations that make low-cost ceramic water filters for poor communities in the less-developed world.

Talk aids medical decisions

Family caregivers who had not discussed life support measures with critically ill patients took nearly two weeks longer to decide to forgo further medical intervention than those who had prior conversations about the issues, according to researchers from the School of Medicine and the Graduate School of Public Health (GSPH).

They recently presented their findings at the Society of Critical Care Medicine congress in San Diego.

A patient’s loved ones were more confident about acting as surrogate decision-makers when they perceived their communication with intensive care physicians to be of high quality, said senior investigator Douglas B. White, a faculty member in critical care medicine and director of its program on ethics and decision-making in critical illness.

“This is the first evidence to suggest that how a doctor guides family members through the foreign territory of critical illness may influence their ability to act as a surrogate,” he noted. “Teaching doctors to be better communicators may be an important step in improving end-of-life decisions for patients. The study also reinforces the value of patients, families and friends having prior conversations about the end of life so that they can feel comfortable with their decisions about medical care.”

For the study, conducted at four intensive care units at the University of California-San Francisco Medical Center between 2005 and 2008, the researchers surveyed 230 caregivers who were making decisions on behalf of incapacitated patients on ventilators with greater than a 50 percent chance of dying from their illnesses.

They found caregivers who hadn’t had a prior conversation with patients about treatment preferences were less confident about making decisions and it took them 40 percent longer — 33 days versus 21 days — to decide to discontinue life support.

“This prolongation of the dying process may not be in the best interest of patients and it places an enormous burden on the health care system,” White said.

“Health care reform will provide incentives for formal advance care planning between physicians and patients, such as the completion of advance directives and living wills. Our findings indicate that informal conversations between patients and their families may be very important for both patient-centered decisions and the family’s comfort with the huge responsibility of being a surrogate.”

The research team included Seo Hong and Lisa Weissfeld of GSPH and Alyssa Majesko of UPMC.

The project was funded by the National Institutes of Health.

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The University Times Research Notes column reports on funding awarded to Pitt researchers as well as findings arising from University research.

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