The overlap of green (glial cells) and purple (water channels embedded in the walls of those cells) show the tubes.
Your blood vessels aren’t the only network of tubes winding through your body. The lymph vessels, or lymphatics, shadow blood vessels wherever they go and collect waste from around the body, as well as shuttling around immune cells and performing other functions. But the lymphatics never make it to the brain, scientists were surprised to find some years ago. Some other, mysterious method for removing waste from the brain must exist.
In a new paper in Science Translational Medicine, a team of neuroscientists reports that they’ve discovered a system of tubes that encircle the blood vessels that feed the brain. The walls of these tubes are made up of spindly projections from brain cells called glia, that, in the same way that trees’ arching limbs form a tunnel over a road, arch around the blood vessels to form the tubes. And these tubes seem to drain the way lymphatics do, suggesting that they might be long-sought gutter of the brain.
Amyloid beta deposits in brain of Alzheimer’s patient.
What’s the News: A drug used to cure skin cancer is also a possible treatment for Alzheimer’s, according to a new study in Science. The drug not only reduced levels of amyloid beta—a protein whose elevated levels are a hallmark of the disease—but also reversed cognitive decline. In mice, dramatic effects were evident after just 72 hours.
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.
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.
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.
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. Read More
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.
Alzheimer’s: It’s a disease that afflicts over five million Americans, and there is currently no treatment for it. But researchers are getting closer to a diagnostic test for the disease. Last week a Food and Drug Administration (FDA) advisory committee recommended that the agency approve a brain scan that can detect the disease in a living patient.
The approval would be for a dye that homes in on plaque in the brain, making it visible on PET scans. Such scans would be especially valuable in a common and troubling situation — trying to make a diagnosis when it is not clear whether a patient’s memory problems are a result of Alzheimer’s disease or something else. If a scan shows no plaque, the problems are not caused by Alzheimer’s and could be from tiny strokes or other diseases. [New York Times]
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.
Two recent studies are refuting the claims of omega-3 enthusiasts that the fatty acid, which is produced mainly by algae and is found in the animals that eat them (like fish), is the ultimate “brain food.”
Anecdotal reports had suggested that these fatty acids, called omega-3 because they have a kink in their structure three bonds from the end of the carbon chain, could improve brain function for everyone from the elderly to the unborn. Vitamin supplements of fish oil have therefore been flying off the shelves.
People who eat lots of fish are less likely to develop dementia or cognitive problems late in life. Observational studies have also found that taking omega-3s during pregnancy can reduce postpartum depression and improve neurodevelopment in children. What’s more, animals with an Alzheimer’s-like condition are helped by docosahexaenoic acid (DHA), one of several omega-3 fatty acids. And DHA disappears from the brains of people with Alzheimer’s. [ScienceNOW]
In an Alzheimer’s study published in The Journal of the American Medical Association, researcher Joseph Quinn gave about 400 patients suffering from mild to moderate Alzheimer’s 2 grams of either omega-3 DHA or a placebo each day. After 18 months, none of the patients showed improvement of their Alzheimer’s symptoms.