Moderate elevations of homocysteine are associated with a fivefold increase in the risk for stroke and almost triple the risk for Alzheimer’s disease, according to a study in the October Stroke. Researchers examined the levels of this amino acid in 83 patients with Alzheimer’s disease, 78 patients with vascular dementia, 64 stroke patients, and 71 healthy volunteers. After adjusting for risk factors, investigators determined that patients with elevated homocysteine had a 2.9 times greater risk for developing Alzheimer’s disease than did volunteers with lower levels of homocysteine. The stroke risk was 5.5 times greater, and for vascular dementia, it was 4.9 times greater. Researchers suggest that B vitamin supplementation may be one approach to lowering homocysteine levels.

Investigators from the National Human Genome Research Institute have discovered the genetic cause for a rare form of microcephaly that has affected infants among the Old Order Amish for nine generations. During the past 40 years, 61 babies with Amish microcephaly have been born to 23 families in Lancaster County, Pennsylvania; none of the children has lived more than 14 months. The genealogy of the Old Order Amish revealed that all 23 families who had children with this disorder descended from a single Old Order Amish couple. Researchers discovered that this gene defect causes developing cells to lose their ability to transport base pairs of DNA across the inner membrane walls of mitochondria. They believe that without this carrying ability, mitochondria cannot make DNA properly, causing abnormal brain development in the unborn child. The study appeared in the September Nature Genetics.

Early diagnosis of Alzheimer’s disease using positron emission tomography (PET) can cut unnecessary drug therapy by nearly half and reduce months in a nursing home by more than 60%, reported a study in the October Molecular Imaging and Biology. Researchers from the University of California, Los Angeles compared two diagnostic models, one using the American Academy of Neurology’s (AAN) 2001 recommendations for clinical evaluation of dementia, the other using the AAN’s recommendations and PET to measure the patient’s brain metabolic patterns. Investigators determined that using PET could reduce erroneous diagnoses by half, and the introduction of PET into patients’ assessments corresponded to a 62% decrease in avoidable months of nursing-home care and a 48% drop in unnecessary drug treatment.

Patients with acute carbon monoxide poisoning are significantly less likely to suffer long-term neurologic and cognitive problems if they are treated promptly with highly pressurized oxygen in a hyperbaric chamber. A randomized double-blind study of 152 patients with carbon monoxide poisoning treated with either hyperbaric-oxygen therapy or normobaric-oxygen therapy between November 1992 and February 1999 found that hyperbaric-oxygen therapy reduced the frequency of cognitive problems in patients by nearly 50% six weeks after they were poisoned. Researchers also observed that 12 months after being poisoned, patients who received hyperbaric oxygen experienced significantly fewer long-term cognitive problems than did patients given regular oxygen through a face mask. The study was published in the October 3 New England Journal of Medicine.

Air pollutants are significantly associated with ischemic stroke mortality, according to an article published in the September Stroke. Researchers in Seoul, South Korea, obtained data regarding stroke deaths that occurred between January 1, 1991, and December 31, 1997, from the Korean National Statistical Office; they analyzed ischemic and hemorrhagic stroke deaths separately. Air pollution data were analyzed according to daily stroke deaths, and researchers controlled for time trends, day of the week, and meteorologic influences such as temperature, relative humidity, and atmospheric pressure. The investigators reported that the effects of air pollutants on ischemic stroke mortality were statistically significant, which may suggest an acute pathogenic process in the cerebrovascular system caused by air pollution; the air pollutants’ effects on hemorrhagic stroke mortality were not significant. Researchers also believe that “an explanation for the biological plausibility of these relationships is still required.”

People with migraines perform more poorly on cognitive tests than do those without headaches, investigators from New Zealand recently reported, but these poor performances are not the result of cumulative attacks and are most likely due to developmental factors. The study, which appeared in the September 24 Neurology, diagnosed 980 members from the Dunedin Multidisciplinary Health and Development Study with either migraine, tension-type headache, or no headache. Data related to the subjects’ cognitive and academic performance from ages 3 to 26 were analyzed. The researchers determined that migraineurs were “subtly but significantly impaired” on tests of verbal ability from ages 3 to 13, regardless of headache history. However, because the study determined that cognitive performance was unrelated to length of headache history or severity of migraine attack, researchers feel that migraine and verbal impairment are associated because of a shared risk factor.

Protocol deviations frequently occur when thrombolytic therapy is given to stroke patients in clinical practice, leading to higher rates of in-hospital mortality and serious extracranial hemorrhage, according to a report in the September 23 Archives of Internal Medicine. Researchers compared the outcomes of patients given intravenous thrombolysis in clinical practice in Connecticut hospitals with the results of the National Institute of Neurological Disorders and Stroke rt-PA Study (NINDS cohort). They examined factors such as in-hospital mortality, intracranial hemorrhage, extracranial hemorrhage, and major and minor protocol deviations. The investigators found that 63 patients were given therapy in hospitals and that in-hospital mortality was substantially higher in the Connecticut cohort (25%) than in the NINDS cohort (13%). In addition, the rate of serious extracranial hemorrhages was higher in the Connecticut cohort (13%) than in the NINDS cohort (2%). At least one major protocol deviation was observed in 67% of the patients treated in Connecticut, and 97% of patients had at least one major or minor deviation.

The presence of a lupus anticoagulant should be considered as an independent risk factor for ischemic stroke in young women, according to a study in the October Stroke. Researchers examined antiphospholipid antibodies using stored frozen sera and plasma in 160 patients and 340 controls enrolled in the Stroke Prevention in Young Women study. Investigators discovered that a positive anticardiolipin antibody of any isotope was seen in almost 27% of the patients and 18% of controls, lupus anticoagulant was found in approximately 21% of patients and 13% of controls, and either anticardiolipin antibody or lupus anticoagulant was observed in approximately 42% of patients and 28% of controls. After adjusting for risk factors, researchers determined that the relative odds of stroke for women with anticardiolipin antibody of any isotope or a lupus anticoagulant was 1.87 and emphasized the importance of evaluating patients for lupus anticoagulants.

Despite case studies proposing a link between roller coaster rides and brain injury, researchers from the University of Pennsylvania concluded that roller coasters do not produce forces great enough to cause brain injury. The researchers examined the three basic features of G forces as experienced by riders: the magnitude of the force, the direction of the acceleration, and the time interval during which the acceleration occurs. They acquired G force data from three of the most popular and powerful roller coasters in the country and, using this data, calculated peak head accelerations in three directions. Even considering the worst-case scenario, the researchers found that the greatest forces experienced on roller coasters were far below those that are known to cause injury. The study was published in the October Journal of Neurotrauma.

Personality should be taken into consideration as a potential vulnerability factor for depression in stroke patients, according to an article published in the October Stroke. Researchers assessed 190 patients who were diagnosed with ischemic stroke for the first time. The patients were asked to complete the NEO-Five Factor Inventory, which examines five main dimensions of personality: neuroticism, extraversion, openness to new experiences, agreeableness, and conscientiousness. Depressive symptoms were assessed every three months for a year after stroke using self-rating questionnaires. Researchers found that the incidence of poststroke depression was 38.7% and that patients with depression scored an average of five points higher on the neuroticism scale than did patients without depression. No other personality trait was shown to affect depression.

Researchers can effectively deliver drugs to the primate brain stem and monitor the drugs’ spread in the brain. In a report published in the October Journal of Neurosurgery, the investigators used a technique called convection-enhanced delivery to inject a tracer molecule into the brain stem and tracked the tracer’s movement with magnetic resonance imaging. Convection-enhanced delivery uses small differences in pressure to make infused molecules flow through solid tissue, enabling large-molecular-weight molecules to penetrate the brain stem. Gd-albumin was injected into the pontine region of the brain stem of three healthy monkeys, and the animals were imaged during the infusion and one, two, four, and seven days following infusion. Tests up to 35 days after infusion showed no neurologic abnormalities, and the brain stem tissues appeared normal. Researchers are currently testing several drugs for toxicity and effectiveness using convection-enhanced delivery and magnetic resonance imaging in animal studies.

Researchers have shown that stem cells can repair degenerating neurons in mice with symptoms of Parkinson’s disease, stated an article in the October 15 Nature Biotechnology. The investigators injected the mice with MPTP, which causes dopamine neurons to disintegrate and eventually die. After a week, more than 60% of the dopamine neurons in the substantia nigra of the mice had stopped producing the neurotransmitter. The researchers injected cultured neural stem cells into one side of the mice’s brains; after three days, the mice began walking in circles, indicating that the neurons were producing dopamine. After three weeks, symptoms disappeared entirely. Researchers were surprised to learn that only 10% of the functioning dopamine neurons originated from the stem cells, indicating that the stem cells repaired the other 90% instead of replacing them.

NR

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