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Vitamin B₁₂ may help to protect people against Alzheimer’s disease, a small study suggests. But other studies in this area have had mixed results. Some have found a link between B₁₂ and Alzheimer’s risk. Others have not. The new study included 271 Finns. They were 65 to 79 years old at the start of the study. At that time, they did not have Alzheimer’s or other dementia. Researchers gave people blood tests. They measured levels of homocysteine, one of the building blocks of proteins. People with high homocysteine levels have a greater risk of stroke. They also measured the active form of B₁₂, which lowers homocysteine levels. During the next 7 years, 17 people developed Alzheimer’s disease. People with higher levels of homocysteine also were more likely to develop Alzheimer’s.

An osteoporosis drug also may help to rebuild lost bone in the jaw, two new studies have found. One study describes a woman who had taken the osteoporosis drug alendronate (Fosamax) for 10 years. She developed a rare side effect called osteonecrosis in her jaw. This condition kills bone cells. Doctors tried treating her jaw with a different osteoporosis drug. This drug was teriparatide (Forteo). It is a form of parathyroid hormone made in a laboratory. This drug stimulates the body to rebuild lost bone. After 8 weeks of teriparatide injections, the woman’s jaw healed. Another study involved 40 people. They had bone loss in the jaw caused by periodontal (gum) disease. They all had jaw surgery. Then they were randomly assigned to receive either teriparatide or fake (placebo) injections. They were treated for 6 weeks. People who got the teriparatide healed better.

Authors of a new study say children adopted from outside the United States should be tested for hepatitis A. The study found that nearly one-third of these children may be immune to the virus. Therefore, they would not need vaccinations. About 1% of the children had active infections that they could spread to others. But most did not have symptoms. Therefore, U.S. health officials recommend hepatitis A shots for all people who adopt from countries where infection with the virus is widespread. This should occur at least two weeks before they meet the child. The new study looked at blood tests for 288 children. All had been adopted from abroad. Overall, 29% had antibodies that showed they were immune to hepatitis A. Immunity varied by region. The highest rate was 72% among African children. About 39% of Latin American and Caribbean children were immune.

Older adults who regularly walk at least 6 miles a week may be less likely to develop dementia, a study suggests. The study included nearly 300 adults. Their average age was 78. Researchers asked them how many blocks they walked each week. Nine years later, they were given magnetic resonance imaging (MRI) scans to measure brain volume. People who walked at least 72 blocks a week (6 to 9 miles) had more gray matter in the brain. Then, 4 years after the MRI, people were given tests related to cognitive ability (thinking and memory). The tests showed about 40% had either dementia or a mild cognitive impairment, which can lead to dementia. But people with more gray matter were only half as likely as others to have these problems. There was no benefit for people who walked fewer than 6 miles a week, researchers said. The journal Neurology published the study online.

People with peripheral artery disease (PAD) have high medical costs, a new study finds. And better treatments are needed, the research suggests. PAD is a narrowing of arteries in the legs. It causes pain during walking. The study kept track of 1,600 people with PAD for 2 years. Nearly 1 out of 3 people had a hospital stay related to PAD. Hospital costs were about $7,000 for a person who had no previous procedures to open up a leg artery. But having these treatments did not keep people out of the hospital. In fact, hospital costs went up. They averaged $11,700 for people who had a previous procedure. The study appeared October 13 in the journal Circulation: Cardiovascular Quality and Outcomes.

Doctors use two ways to open up blockages in neck (carotid) arteries. They do surgery or insert a tube called a stent. A new review of research finds that the risk of stroke, heart attack or other problems is different after each of the two procedures. Researchers put together the results from 13 studies that compared the two approaches. They included nearly 7,500 people. Those who got stents had a 65% higher risk of death or stroke within 30 days than those who got surgery. But in that period, people who had surgery were more likely to have other problems. Their chance of having a heart attack was 55% higher than for those who got a stent. Their chance of nerve paralysis was 85% higher. Authors of the study said more research is needed to determine who is most likely to benefit from each procedure. The study appeared in the journal Archives of Neurology.

With a big ad campaign about “hands-only” CPR, Arizona greatly increased the number of bystanders who tried it, a new study found. And people were more likely to live than when rescuers used traditional CPR. Arizona used public service ads, YouTube videos, free classes and other means to spread the word about hands-only CPR. This form of CPR uses a series of rapid pushes on the chest to circulate blood. There is no pause for “rescue breaths,” as in traditional CPR. In 2005, when the campaign began, about 28% of bystanders tried to use CPR when someone nearby had a cardiac arrest. In 2009, after the campaign, 40% tried CPR. More people used the hands-only method as time went on. People who got hands-only CPR were more likely to survive — 13% compared with 8% for traditional CPR. The study appeared in the Journal of the American Medical Association.