Neurosciences - February 2012 Archives

ROCHESTER, Minn. — Mitochondria — subunits inside cells that produce energy — have long been thought to play a role in Alzheimer's disease. Now Mayo Clinic researchers using genetic mouse models have discovered that mitochondria in the brain are dysfunctional early in the disease. The findings appear in the journal PLoS ONE. The group looked at mitochondria in three mouse models, each using a different gene shown to cause familial, or early-onset, Alzheimer's disease. The specific mitochondria changes corresponded with the mutation type and included altered mitochondrial movement, structure, and energy dynamics. The changes happened in the brain even before the mice showed any symptoms such as memory loss. The group also found that the mitochondrial changes contributed to the later loss of mitochondrial function and the onset and progression of Alzheimer's disease. "One of the most significant findings of this study is our discovery of the impact of mitochondrial dysfunction in Alzheimer's disease," says Eugenia Trushina, Ph.D., Mayo Clinic pharmacologist and senior investigator on the study. "We are asking: Can we connect the degree of mitochondrial dysfunction with the progression of symptoms in Alzheimer's disease?" Enlisting the expertise of Mayo researcher Petras Dzeja, Ph.D., the team applied a relatively new method called metabolomics, which measures the chemical fingerprints of metabolic pathways in the cell — sugars, lipids, nucleotides, amino acids and fatty acids, for example. It assesses what is happening in the body at a given time and at a fine level of detail, giving scientists insight into the cellular processes that underlie a disease. In this case, the metabolomic profiles showed changes in metabolites related to mitochondrial function and energy metabolism, further confirming that altered mitochondrial energetics is at the root of the disease process.

ROCHESTER, Minn. — In a reversal of two decades of medical reports, a Mayo Clinic study finds the frequency of nerve damage called diabetic polyneuropathy is similar in prediabetic patients and healthy people. Physicians should seek explanations other than prediabetes for patients who have painful small fiber polyneuropathy, the researchers say. The study was published in the March issue of Diabetes Care. Diabetic polyneuropathies, or DPN, are commonly associated with diabetes and chemical derangements related to high blood sugar. The neuropathies can injure nerve fibers throughout the body, but usually affect the feet and legs. The nerve damage can create sensory, motor and bodily function problems. DPN can be painful and life-threatening. "It is highly unlikely that impaired glucose or associated metabolic derangements cause polyneuropathy, at least not to the high frequency previously reported," says lead author Peter J. Dyck, M.D., a Mayo Clinic neurologist. The five-year study, "Impaired Glycemia and Diabetic Polyneuropathy: The OC IG Survey," tested nearly 550 people representative of a community of older patients of Northern European extraction. Of these, 150 individuals were healthy subjects, 174 had prediabetes indicators, and 208 had newly developed type 2 diabetes. The study concluded that typical or atypical (a painful small-fiber variety) DPN was not more prevalent in prediabetics than in healthy people.

SCOTTSDALE, Ariz. — A new study from Mayo Clinic supports the idea that "what's good for your heart is good for your brain." The study, released today, suggests that eating too much may double the risk for memory loss in people age 70 and older. This research will be presented at the American Academy of Neurology's 64th Annual Meeting in New Orleans April 21 to April 28. VIDEO ALERT: Click here for a video of Dr. Geda explaining the study. "We observed a dose-response pattern which simply means; the higher the amount of calories consumed each day, the higher the risk of mild cognitive impairment," said study author Yonas E. Geda, M.D., MSc, a neurologist and psychiatrist with Mayo Clinic in Arizona. He noted that 2,143 calories per day may double the risk of memory loss. While the relationship between cardiovascular problems and overeating are well known, the study further documents the similarities of cardiovascular risks and neurological risks such as mild cognitive impairment, Dr. Geda says. MCI is the stage between normal memory loss that comes with aging and early Alzheimer's disease. The study involved 1,233 people in Olmsted County, Minn., ages 70 to 89 and free of dementia. Of those, 163 had MCI. Participants reported the amount of calories they ate or drank in a food questionnaire and were divided into three equal groups based on their daily caloric consumption. One-third consumed 600 to 1,526 calories per day, one-third 1,526 to 2,143 calories and one-third 2,143 to 6,000 calories per day. The odds of having MCI more than doubled for people in the highest calorie-consuming group compared with people in the lowest calorie-consuming group. The results were the same after adjusting for history of stroke, diabetes, amount of education and other factors that can affect risk of memory loss. There was no significant difference in risk for the middle group.

On Saturday, February 25th our guest was Mayo Clinic physician Dr. Ronald Petersen discussing Alzheimer's disease. Medical Edge Weekend 2-25-12 The Mayo Clinic Alzheimer's disease blog can be found ...

PHOENIX — It's been said that marriage is good for your health — especially if you're a man. Research at Mayo Clinic in Arizona shows that's true when it comes to seeking care for stroke symptoms. A Mayo Clinic study, presented at the American Stroke Conference in New Orleans in early February, says that men experiencing a stroke call for emergency help quicker than women, especially if they are married. "Marriage has long been shown to offer health benefits and often more for men," said Joyce Lee-Iannotti, M.D., a neurology Fellow at Mayo Clinic in Arizona and author of the study. "The reasons are unclear, but it's been postulated that it can be societal roles, where women take on the roles of caregivers and advise their spouses to seek care, often putting their own health behind that of their children and husband." VIDEO: Dr. Lee-Iannotti explains the study. The study was a retrospective review of 209 patients with acute stroke symptoms brought by emergency medical services to Mayo Clinic in Phoenix over 15 months ending in November 2011. Researchers collected participants' age, gender, marital status, time of symptom awareness and time of emergency medical services dispatch. They compared the time from symptoms awareness to EMS dispatch between married and single participants and between men and women. Married men called within 28 minutes of symptoms compared to married women, who called an average of 67 minutes after their first stroke symptoms. Single men activated EMS earlier than single women, but the difference was not significant.

JACKSONVILLE, Fla. — A research team led by investigators at Mayo Clinic in Florida has found that a small device worn on a patient's brow can be useful in monitoring stroke patients in the hospital. The device measures blood oxygen, similar to a pulse oximeter, which is clipped onto a finger. VIDEO ALERT: Additional audio and video resources, including comments by Dr. Freeman about the new device, are available online. Their study, published in the Feb. 1 issue of Neurosurgical Focus, suggests this tool, known as frontal near-infrared spectroscopy (NIRS), could offer hospital physicians a safe and cost-effective way to monitor patients who are being treated for a stroke, in real time. "About one-third of stroke patients in the hospital suffer another stroke, and we have few options for constantly monitoring patients for such recurrences," says the study's senior investigator, neurocritical care specialist William Freeman, M.D., an associate professor of neurology at Mayo Clinic. "This was a small pilot study initiated at Mayo Clinic's campus in Florida, but we plan to study this device more extensively and hope that this bedside tool offers significant benefit to patients by helping physicians detect strokes earlier and manage recovery better," he says.