St. Paul, Minn. – Increased risk for neurological disease from military service, new genes for Parkinson's disease, modifiable risk factors for dementia, and the educational value of medical malpractice cases were among the scientific highlights of the 56th Annual Meeting of the American Academy of Neurology. Results from more than 1,300 scientific studies were presented to an audience of more than 8,000. Some of the most important findings were presented in a plenary session by John Noseworthy, MD, chair of the AAN Science Committee and professor of neurology at the Mayo Clinic in Rochester, Minn. Highlights included:
Mexican-Americans have significantly higher rates of stroke than non-Hispanic whites, according to research by a group from the University of Texas at Houston. The disparity occurs at all ages, but is greatest among those ages 45 to 49, in whom the risk for stroke is more than twice that of whites. "As the Mexican-American population grows and ages, measures to target this population for stroke prevention are critical," the authors stated. [S09.005]
Transfusion reduces stroke rates in children with sickle cell disease (SCD), based on a long-term study by researchers at the University of California, San Francisco. Rates of stroke were compared for children with SCD before and after the 1998 publication of a treatment protocol recommending early transfusions in this population. Fewer children with SCD are now being admitted to hospital in California with their first stroke perhaps suggesting that earlier treatment may reduce stroke risk, with the figure for 2000 less than one quarter of that seen throughout the 1990s by more than 75 percent. [S04.005]
The thrombin inhibitor ximelagatran is at least as effective as standard warfarin treatment for stroke prevention, and unlike warfarin, can be used in a fixed dose and without coagulation monitoring. In two large double-blind international trials comparing the two, patients at risk for stroke because of non-valvular atrial fibrillation were randomly assigned to receive one of the two drugs. Stroke rates were similar with both treatments but ximelagatran had a lower risk of hemorrhagic complications. Ximelagatran caused approximately 20 percent fewer incidents of major and minor bleeding combined but was associated with increase in liver enzymes in six percent. [PL01.003]
Brain surgery has become a major treatment for medically intractable epilepsy. Because of its invasiveness and risks, however, patients need reassurance that the benefit is likely to be long-lasting. A study from the Mayo Clinic in Rochester, Minn. showed that after two to three years, the percentage hold steady at approximately 70 percent. This means that if a patient remains seizure-free for two to three years after surgery, they are likely to remain so afterward. "This is a reassuring finding for our patients," said Dr. Noseworthy. [S14.001]
Despite its proven effectiveness for medically intractable temporal lobe epilepsy due to mesial temporal sclerosis (MTS), African Americans in Alabama undergo surgery at less than half the rate of whites. Researchers from the University of Alabama at Birmingham discovered this disparity in a review of medical charts of 122 patients at a regional epilepsy treatment center with temporal lobe epilepsy and evidence of MTS on their brain scans. "Race appears to be an important factor related to such disparities," according to lead author Jorge Burneo, MD, "but the causes remain unclear, and they appear not to be related to a difference in access to care." [S09.006]
Dementia is a common consequence of advanced HIV infection. Two-thirds of all HIV-infected individuals--more than 26 million people--live in sub-Saharan Africa, and yet little is known about prevalence of dementia in this infected population. Using a simple clinical interview, researchers in Canada and Uganda showed that 31 percent of all HIV-positive patients in Uganda have mild or moderate dementia, and another 46 percent have subclinical cognitive impairment, similar to rates in more developed countries. [S52.002]
Two studies examined risk factors for dementia. Researchers from Harvard Medical School showed that older women with type 2 diabetes have a 30 percent greater risk for poor cognitive function than women without diabetes, and this increased risk grows to 50 percent after 15 years of disease. Controlling diabetes symptoms can eliminate this increased risk. Treated women were not at an increased risk, a finding that emphasizes the importance of medical treatment for diabetes. Known risk factors for cardiovascular disease also increase risk for dementia, according to research from University of California, San Francisco. Those with hypertension, diabetes, smoking, and high cholesterol had two and a half times the risk for dementia as those with none of these risk factors. "These are modifiable risk factors for dementia in the elderly, and treatment should address reducing these risks," Dr. Noseworthy stressed. [S27.002, S54.001]
Diabetes and impaired glucose tolerance can also cause peripheral nerve disease. Researchers from the University of Utah and elsewhere showed that the pain from peripheral neuropathy could be reduced significantly by weight loss and by exercise. [S31.006]
Military Service and Neurological Disease
Much controversy has surrounded the question of whether Gulf War veterans have developed neurological diseases at higher rates than their non-deployed counterparts. In a study of more than 2,000 veterans, researchers at the Department of Veterans Affairs found no difference in the rate of peripheral neuropathy between deployed and non-deployed soldiers, either by neurological exam or by lab investigation. [S32.001]
Meanwhile, a group from Harvard School of Public Health showed an increased risk of death from amyotrophic lateral sclerosis (ALS) in soldiers who entered service between 1906 and 1982. Their study of over half a million men indicated that veterans had a 60 percent increased risk of death from ALS compared to non-veterans, independent of branch of service, duration of service, or the time period in which they served. [S32.002] A study by the same group found the risk of death from ALS can be reduced slightly by long-term regular use of vitamin E supplements. [S32.004]
Two new genetic findings regarding Parkinson's disease (PD) were announced at the meeting. Specific forms of the ApoE gene have long been known to affect risk for Alzheimer's disease. By combining results from 20 studies on ApoE in PD, researchers from the University of North Carolina showed that ApoE-2 increases the risk for PD very slightly even though the same gene is protective in Alzheimer's disease. [S08.004] The identity of a previously discovered gene, PARK6, was announced. PARK6 codes for PINK1, a previously identified protein that acts within mitochondria, cell structures that regulate energy use. Mutations in PARK6 may lead to decreased energy regulation and increased susceptibility to cellular stresses and finally PD. [LBS.006]
Researchers from London revealed that long-term treatment with GDNF (glial-derived neurotrophic factor) improves PD symptoms and may help remaining brain cells to recover and function better. The GDNF was delivered directly into the brain through a tube. After two years of treatment, patients needed less medication and had improved by 40 percent on a standard PD disability score. This small, open study is being followed by a larger double-blind trial, currently in progress. [S38.001]
Two studies examined the potential for repairing the adult nervous system after disease or injury. Mayo Clinic researchers showed that a biodegradable implant can act as a scaffold for the regrowth of severed nerves. The implant can be seeded with cells and growth factors to encourage nerve regrowth. It slowly breaks down as it is replaced by normal tissue. [S66.006] Researchers from Germany demonstrated the medical potential of stem cells derived from adult human bone marrow. These stem cells can be converted into neural stem cells, and may be useful for treatment of a variety of diseases, from Parkinson's disease to spinal cord injury. [S66.001]
Finally, a group from Harvard Medical School analyzed neurological medical malpractice claims in order to derive educational lessons for use in medical schools and residency programs. Of the cases they examined, half involved communication errors, including failure to follow up on test results. The authors urged their colleagues to stay involved with the patient, to track and respond to testing results as they become available, and to communicate with the patient, family, and other medical professionals to improve patient care. [P01.146]
New research in multiple sclerosis, West Nile virus, headache, sleep disorders, and neuro-oncology was also presented at the meeting.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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