Twenty percent of elderly patients who have suffered a heart attack have a one in 25 chance of being hospitalized for a stroke within six months of discharge from the hospital, according to researchers at Yale University. As reported in the March Circulation, investigators analyzed data from more than 111,000 elderly patients included in the Cooperative Cardiovascular Project, a large, diverse population-based group of patients hospitalized with acute myocardial infarction. Overall, 2.5% were admitted with an ischemic stroke within six months of discharge. Older patients, African-Americans, patients with any frailty, as well as prior stroke, hypertension, diabetes, atrial fibrillation, heart failure, and peripheral vascular disease are all predictors of stroke after heart attack, said the investigators. The risk of stroke among the 20% of patients who had at least four of these factors was quadruple that in patients with none of these factors.

A new study has shown that recovering memory after brain injury is harder for people who have the e4 allele of the apolipoprotein (APOE) gene. “Although APOE has been implicated in traumatic brain injury recovery before, this is the first time that it has been associated with a specific deficit,” said lead author Fiona Crawford, PhD. “The findings have implications for understanding repair and recovery after traumatic brain injury, as well as the neurodegenerative mechanisms, and suggest common cellular responses in head injury and Alzheimer’s disease.” The study, which appeared in the April 9 Neurology, examined 110 patients with head injuries who were rated for level of traumatic brain injury, assessed for memory function, and genotyped at the APOE gene.

The medial superior temporal area of the brain acts not only like a compass but also as a sort of biologic global positioning system, providing a mental map to help us understand exactly where we are in the world and how we got there, according to researchers reporting in the March 29 Science. Their findings may help explain why people with Alzheimer’s disease have such a difficult time finding their way in the world. “There’s a continuous interaction between where you’ve been, where you’re going, and where you are,” said Charles Duffy, MD, PhD. “What we’ve done is peeked into that process.” Furthermore, he said, “We believe this discovery will help us develop new ways to treat people with Alzheimer’s disease.”

Researchers have identified a gene that is responsible for both intellectual disability and epilepsy. The gene is found on the X chromosome and is one of an estimated 100 genes on that chromosome, which, when mutated, can cause intellectual disability. The gene controls how, where, and when other genes work, thus contributing to the normal cognitive function of the human brain. Seventeen researchers from six countries, led by the Women’s and Children’s Hospital, Adelaide, South Australia, studied the genetic material from nine families worldwide and found that the same mutations in the gene gave rise to epilepsy, including infantile seizures and other types of seizures, dystonia, and intellectual disability. The findings appeared in the March 11 Nature Genetics.

The anger and irritability that stroke patients exhibit may have more to do with an injury to the brain during a stroke than with poststroke depression, according to a study in the April 9 Neurology. Researchers examined 145 patients who had had a stroke. Within three to 12 months, forty-seven (32%) became unable to control anger or aggression as a result of the stroke. In addition, the investigators examined brain lesions and found a correlation between the location of the brain lesion and the appearance of anger and aggression. The inability to control anger and aggression was frequently present when there was a presence of lesions affecting the frontal, lenticulocapsular, and pontine base areas.

By using a longitudinal study, researchers have confirmed that T cells show seasonal fluctuation in patients with multiple sclerosis, and that the T cells are at a high in autumn. “It is clear that activated T cells play an important role in multiple sclerosis disease activity,” said Joep Killestein, MD. “However, the triggering cause is still largely unknown.” He said that although T cells were more activated during the autumn months, as measured by the production of cytokines, there was no discernible change in the lesions in the brain that are inherent to multiple sclerosis. “Viral infections are more common in particular seasons and may be a possible explanation of the fluctuations of immunologic and radiologic effects in multiple sclerosis,” he said. The findings were published in the April 9 Neurology.

Researchers have found that tumor necrosis factor alpha, normally thought to be only a component in the immune system, actually plays a key role in regulating neurotransmission in the central nervous system. The study, published in the March 22 Science, offers new insight into how cells interact within the human nervous system and shows that tumor necrosis factor alpha is vital for controlling the strength of signal transmission between nerve cells. In addition, the level of signal strength may play an important role in determining how nerve cells respond to injury. The researchers hope that their findings may lead to new approaches to treating dementia, Alzheimer’s disease, stroke, epilepsy, and spinal cord injury.

Pregnant or nursing women may be able to reduce their chances of developing postpartum depression and improve the neurologic development of their babies by increasing their consumption of docosahexaenoic acid (DHA), according to researchers reporting at the 223rd Annual Meeting of the American Chemical Society. DHA is an omega-3 fatty acid found mostly in tuna, salmon, and algae. A number of independent studies seem to verify the connection between DHA and postpartum depression, according to David Kyle, PhD. About 15% to 20% of women who give birth in the United States develop postpartum depression, he said. Furthermore, he pointed out, US women typically consume about 40 to 50 mg of DHA in their daily diet compared to about 200 mg for European women and about 600 mg for Japanese women.

A relatively simple memory test can be used to track recovery of brain function in children with traumatic brain injury, according to a report in the online April Annals of Neurology. The test, which involves picking out letters that match or rhyme, is intended to assess the ability to remember and process information within a very short timeperiod or during a specific task. Such “working” memory is one of the functions typically damaged in traumatic brain injury, researchers said. Children with severe brain injuries gave significantly fewer correct responses than did those with mild or no injuries, and the findings “support the feasibility of using these tests, combined with magnetic resonance imaging, for evaluating patterns of brain activation as children use their working memory,” they said.

Using a genetically engineered mouse, researchers at the University of Iowa have shown that an acid-activated protein known as acid sensing ion channel (ASIC) is responsible for acid-generated currents in the brain that play a role in learning and memory. The study, published in the April 25 Neuron, reported that mice without the ASIC protein had no acid-gated currents in their neurons. These impaired mice showed significant learning and memory deficits as compared to normal mice. However, the deficits could be reversed with intensive training, leading researchers to suggest that “the ASIC protein might offer a nice target for medications to improve memory” or alternatively, a way to dampen memory, “which might be useful for treating certain psychiatric illnesses such as posttraumatic stress disorder.” They also postulate that ASIC might be implicated in brain damage associated with stroke and seizure.

NR

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