A protein tangle in an Alzheimer’s-afflicted neuron

Exactly how Alzheimer’s disease proliferates through the brain, overtaking one region after another, has eluded scientists. As the disease progresses, tau—a malformed protein that forms snarls and tangles inside neurons—shows up in more and more brain areas. Researchers have wondered whether tau, and the disease, are working their way out from a single area of origin or mounting numerous, distinct attacks on vulnerable parts of the brain. Two new studies in mice provide strong support for the first idea: Tau seems to pass from affected cells to their neighbors, spreading much the same way a virus or bacteria infection would.

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A twice-daily dose of insulin, sprayed deep in the nose for easy transit to the brain, may slow or stop the progression of Alzheimer’s disease, according to a new pilot study. The researchers gave 104 patients with mild to moderate Alzheimer’s disease or pre-Alzheimer’s cognitive impairment one of three nasal sprays for four months. One group of patients got a nasal spray with a moderate dose of insulin twice a day, one group got a higher dose, and the third got a squirt of saline solution, as a placebo. The memory, cognitive abilities, and day-to-day functioning of patients given insulin stayed constant or improved slightly—particularly for those given the moderate dose of insulin rather than the high dose—while the abilities and memory of patients given the placebo declined.

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What’s the News: A modified antibody can make its way into the brain and target the development of Alzheimer’s-inducing plaques, researchers reported today in two animal studies in Science Translational Medicine. The blood-brain barrier usually keeps drugs and other compounds from entering the brain in large enough quantities to be effective, but these studies show a way to trick the body’s own defenses into letting the drug in, demonstrating that this obstacle to treating Alzheimer’s could potentially be overcome.

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What’s the News: Alzheimer’s is getting an update: for the first time in 27 years, the national criteria for diagnosing the disease have been revised. The new criteria are intended only for use by researchers studying the disease, but they are important because they acknowledge growing evidence for an early stage of Alzheimer’s that could be detectable with biological tests before cognitive impairment sets in. (more…)

A bilingual brain is a healthy brain. (Un cerebro bilingüe es un cerebro sano.)

Speakers of two languages may have extra defenses against the onset of dementia and Alzheimer’s disease—that’s according to new research announced this weekend at the American Association for the Advancement of Science meeting in Washington, DC. Psychologist Ellen Bialystok and her team studied more than 200 Alzheimer’s patients with about the same level of mental acumen, about half of whom were bilingual and half of whom were monolingual. The result: On average, the speakers of multiple languages had been diagnosed four years later in their lives. Says Bialystok:

“Being bilingual has certain cognitive benefits and boosts the performance of the brain, especially one of the most important areas known as the executive control system. We know that this system deteriorates with age but we have found that at every stage of life it functions better in bilinguals. They perform at a higher level. It won’t stop them getting Alzheimer’s disease, but they can cope with the disease for longer.” [The Guardian]

To get a look at that system, the team took CT scans of the patients’ brain. That’s when they found something curious: The physical ravages of Alzheimer’s were actually more advanced in the brains of bilinguals, despite the fact that they were mentally more protected.

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Suppose that Alzheimer’s disease, like a bacterial or viral infection, inspires the immune system to take action and defend the body. If this is true, then there must be antigen proteins that are specific to the disease, which the body recognizes as foreign and which triggers the mustering of a defense. Could doctors catch a glimpse of that process and diagnose the disease earlier? That’s the hope behind a study out this week in Cell, led by Thomas Kodadek.

Many new efforts to speed up diagnosis of Alzheimer’s are ongoing, with some, like Kodadek’s, looking for a signal in the bloodstream. The problem is, scientists don’t know what antigens are the signature of the disease, nor which antibodies the immune system raises to go after them. So they set a trap.

On a slide, Kodadek’s team assembled thousands of different shapes of peptoids—molecules that are slight variations of the peptide molecules found in our bodies—and exposed them to blood samples from people with Alzheimer’s and without. The idea was, if particular peptoids bound only to antibodies from people with Alzheimer’s and not to antibodies of people without, then those antibodies they snagged could be considered a signature of Alzheimer’s in the bloodstream.

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The size of a small part of the brain, right behind the eyes, is connected with a person’s ability to gauge how likely they are to be right about factual questions, according to a study published in Science last week. This faculty is important in many real-world decisions; it can make the difference between relying on our mistaken judgment and asking for help if we realize we might be wrong.

The study’s lead author uses the game show Who Wants To Be a Millionaire? as an prime example of this kind of “metacognition,” or thinking about our own thinking:

“You might have the opportunity to ask the audience or phone a friend,” says Steve Fleming, a neuroscientist at University College London. But, he adds, “You need to know how sure you are about your own answer before you opt to use those lifelines.” [NPR]

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One headline reads “Doing Puzzles ‘Could Speed Up Dementia.’” Another, “Brain Exercise Helps Stave Off Dementia.” They’re both about the same new study out in Neurology this week. So which is it?

Both are shades of the truth, actually. Here’s what the scientists actually found:

Robert Wilson and his colleagues have been tracking more than a thousand people as part of their long-term study, begun in the early 1990s. The patients were 65 or older and the scientists interviewed them every three years.

Participants indicated on a 5-point scale how often they participated in seven activities: viewing television, listening to radio; reading newspapers; reading magazines; reading books; playing games like cards or doing puzzles; and going to museums. (A rating of 5 meant a person did some of these activities about every day; 3 meant several times a month; 1 meant once a year or less) [LiveScience].

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Finally, a big head comes in handy.

For a study out this week in Neurology, scientists looked at 270 Alzheimer’s patients from the Multi-Institutional Research in Alzheimer’s Genetic Epidemiology study (MIRAGE) and found that a larger head size was correlated with better-preserved cognitive and memory skills. The team, led by Robert Perneczky, argues that a bigger cranial circumference could mean a person has more “brain reserve,” offering some protection against the deterioration brought on by Alzheimer’s.

Finding this out took a lot more than just scanning the patients for cerebral atrophy and then wrapping a tape measure around their heads to gauge circumference:

They took blood to see which variant of the APOE gene was in their DNA (having one or two copies of the e4 version of APOE is thought to increase one’s risk of Alzheimer’s). They looked up the results of each patient’s most recent mini-mental state examination (MMSE) to measure cognitive function. They also took into account each patient’s age and ethnicity, how long they’d had Alzheimer’s and whether they had diabetes, hypertension or major depression [Los Angeles Times].

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Back and forth go the studies investigating whether cell phone uses increases the risk of brain cancer (the latest one to get major press, released last month, found nothing there). This week, though, new research has grabbed the headlines by declaring that our ubiquitous communication and time-wasting devices could actually provide a health benefit.

In a study set to come out today in the Journal of Alzheimer’s Disease (and funded in part by the National Institute on Aging), a group led by Gary Arendash argues that the radiation from cell phones that we’ve been worrying about could protect against Alzheimer’s Disease. But it’s far too soon to advise people to start medicating themselves by talking even longer on the phone.

Researchers at the Florida Alzheimer’s Disease Research Center arranged about 70 mouse cages in a circle around a central antenna that emitted electromagnetic waves typical of what would emanate from a phone pressed to a human head. They were exposed to the radiation for two hours a day over seven to nine months. About two dozen other mice served as controls [Los Angeles Times]. Arendash’s team used mice they had genetically engineered to develop the brain buildups and memory problems typical of Alzheimer’s when they got older. The team says that the memory problems of those mice exposed to the radiation began to disappear during the study. Not only that, but normal mice (that hadn’t been genetically engineered) also showed memory improvements after exposure.

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This week, a eight-year double-blind study of the nutritional supplement ginkgo biloba finally reached the pages of the Journal of the American Medical Association. Many health food stores sell ginkgo supplements to people who are hoping to improve their wits and memory, and particularly to elderly people worried about cognitive decline and dementia. But the conclusion by lead researcher Steven DeKosky? Save your money.

In the GEM [Ginkgo Evaluation of Memory] study, participants aged 72-96 years with little or no cognitive impairment were recruited from four communities in the eastern United States and received either a twice-daily dose of 120-milligrams of extract of G biloba or an identical-looking placebo [AFP]. For the more than 3,000 study participants, researchers found no difference in age-related cognitive decline—including the incidence of dementia or Alzheimer’s—between ginkgo takers and placebo takers.

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British researchers have found that giving nicotine to lab rats boosts their concentration and memory, and say that the findings could point the way towards pharmaceuticals that could treat the symptoms of Alzheimer’s and dementia. This benefit may be linked to the effect nicotine has on addicted smokers: The “boost” in concentration that smokers experience from cigarettes could help sufferers fight the mental decline associated with dementia, studies suggest [Telegraph].

Researchers are definitely not suggesting that elderly people take up smoking or start wearing nicotine patches in an attempt to ward off dementia, as the negative health effects would far outweigh any benefits. Lead researcher Professor Ian Stolerman said: “Nicotine, like many other drugs, has multiple effects, some of which are harmful, whereas others may be beneficial. It may be possible for medicinal chemists to devise compounds that provide some of the beneficial effects of nicotine while cutting out the toxic effects” [BBC News].

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