Scholarship & Creativity
Elderly memory loss, cognitive impairment less common

A new nationally representative study shows a downward trend in the rate of "cognitive impairment" — the umbrella term for everything from significant memory loss to dementia and Alzheimer's disease — among people aged 70 and older.

The prevalence of cognitive impairment in this age group went down by 3.5 percentage points between 1993 and 2002 — from 12.2 percent to 8.7 percent, representing a difference of hundreds of thousands of people.

And while the reasons for this decline aren't yet fully known, the authors say today's older people are much likelier to have more formal education, higher economic status and better care for risk factors such as high blood pressure, high cholesterol and smoking. Among the 11,000 people in the study, those with more formal education and personal wealth were less likely to have cognitive problems.

The study is published online in the journal Alzheimer's and Dementia by a team led by two Medical School physicians and their colleagues. The study is based on data from the Health and Retirement Study, a national survey of older Americans funded by the National Institute on Aging and based at the Institute for Social Research (ISR).

Lead author Dr. Kenneth Langa calls the findings good news for today's seniors, noting the new data support recent theories of how brains can be protected and preserved.

"From these results, we can say that brain health among older Americans seems to have improved in the decade studied, and that education and wealth may be a big piece of the puzzle," says Langa, an associate professor of internal medicine who also holds appointments in ISR and the VA Ann Arbor Healthcare System.

Meanwhile, they say, today's older Americans should not rest on their laurels but instead should pursue activities that can keep their minds sharp and their cardiovascular risk low. From crossword puzzles and volunteer activities to blood pressure medications, today's seniors can work to boost their brain health now and prevent decline later.

Additional authors are Dr. Allison Rosen, assistant professor of internal medicine at U-M and the Ann Arbor VA; Mohammed Kabeto, general medicine; and Dr. Scott Kim, Department of Psychiatry, Bioethics Program and Center for Behavioral and Decision Sciences in Medicine.

Loss of resources caused depression in Gaza refugees

Forcing people to leave their homes in the Gaza Strip did not alone cause depression or post-traumatic stress disorder, U-M research shows. Rather the loss of social and economic resources that accompanied the move was the biggest predictor of mental health.

The study shows that women were more likely to have depression, and older people were more likely to have post-traumatic stress disorder, says Sandro Galea, associate professor of epidemiology at the School of Public Health.

The common thread among all the groups was that tangible economic or social losses — such as loss of a job, house or family links — were the biggest predictors of declining mental health, depression and stress disorders.

Researchers interviewed 190 former residents of the Gaza Strip a week before the August 2005 forced evacuation, asking them a series of questions to assess their economic and personal losses, as well as their symptoms.

The study examines the notion that mental health is tremendously affected by loss of material and social resources, Galea says.

"Which also means it's probably very important for physical health as well," he says.

All of the study interviewees were forced to leave their homes in Gaza, but they suffered social and economic losses to different degrees, Galea says. Some moved directly to other occupations, while some moved and settled again with their families or neighborhoods so they kept social links intact.

The results suggest that if a catastrophic event like the Gaza relocation is unavoidable, material support is critical for people in traumatic situations to protect them from financial and social loss to ensure their emotional and physical well-being, Galea says.

Galea, who studies the effect of disasters on mental health, says the prevalence of depression after a major disaster is about twice the baseline of what researchers expected.

"We frequently think of these as social service interventions," Galea says. "The argument that emerges is the loss of these tangible resources is a tremendous risk factor to health, and the effort to buffer them from these circumstances should focus on mitigating social and economic losses."

The paper, "The Psychological Impact of Forced Settler Disengagement in Gaza: Trauma and Post-traumatic Growth," appears in the Feb. 20 issue of the Journal of Traumatic Stress.

Obese kids have more respiratory problems during surgery

A new study from the U-M Health System (UMHS) finds that obese children are much more likely than normal-weight children to have problems with airway obstruction and other breathing-related functions during surgery.

Obese children were found to have a higher rate of difficult mask ventilation, airway obstruction, major oxygen desaturation (a decrease in oxygen in the patient's blood) and other airway problems. The study appears in the March issue of the journal Anesthesiology.

"To our knowledge, this is the first study of its kind," says lead author Alan Tait, professor in the Department of Anesthesiology at UMHS. This large-scale prospective study examines the effect of overweight and obesity on the outcomes of operations in children undergoing elective noncardiac surgery.

"Based on current trends, it is likely that anesthesiologists will continue to care for an increasing number of children who are overweight or obese," Tait says, "so it is vital that we are aware of the higher risk they face in the operating room."

In addition to problems the obese patients experienced during surgery, they also had a higher rate of illnesses and conditions including asthma, hypertension, sleep apnea and Type II diabetes. These conditions all can contribute to problems during surgery, Tait notes.

By the numbers:

• An estimated 15-17 percent of children and adolescents in the United States are considered obese

• Major airway obstructions occurred in 19 percent of obese children, compared with 11 percent of normal-weight children

• Nearly 9 percent of obese children experienced difficult mask ventilation, compared with 2 percent of normal-weight children

• 17 percent of obese children in the study experienced major oxygen desaturation (decreased oxygen in the blood), compared with 9 percent of normal-weight children

• 28 percent of obese children had asthma, compared with 16 percent of normal-weight children

It should be noted, however, that despite the increased risk of adverse events among children who are obese, none resulted in significant illness.

In addition to Tait, authors include Ian Lewis, Terri Voepel-Lewis, Constance Burke and Dr. Amy Kostrzewa, all of the Department of Anesthesiology.

New computer network security threat identified

Large companies are vulnerable to hackers when they network their computers for cost-saving live virtual machine migration, U-M researchers say.

Virtualization, which allows multiple operating systems, or "virtual machines" and their applications to share one physical server, has been possible for decades, but live virtual machine migration is relatively new.

It allows individual virtual machines to migrate among several servers throughout the day with little service downtime, equalizing the load on the servers as it fluctuates. The security of live virtual machine migration has not been studied extensively, but the set-up is common today in large companies.

Hackers could intercept data and compromise the integrity of a virtual machine's operating system during live migration, says Jon Oberheide, a doctoral candidate in the electrical engineering and computer science department. The most popular software doesn't encrypt the information as it travels from server to server.

How does Oberheide know this? He hacked into his own migrating virtual machines.

"I was setting up a live virtual machine migration network in my office and I started poking around, and I noticed that it was totally insecure," Oberheide says.

As a short-term fix, companies can isolate their migration network from other network traffic or install hardware encryption devices on all their physical servers, he says.

"The important thing is to raise awareness of the vulnerability," Oberheide says. "Solutions are feasible, but they're not implemented by the most popular vendors. What is really needed is authenticated and encrypted migration so the attacker cannot perform these attacks, so that even if he can see the migration, he can't modify it."

Oberheide detailed his findings last week in a talk at the Black Hat D.C. computer security conference, where he presented the paper "Empirical Exploitation of Live Virtual Machine Migration." Other authors are research fellow Evan Cooke and professor Farnham Jahanian, both of the Department of Electrical Engineering and Computer Science.