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.
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.
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].
Researchers have tested a new pharmaceutical approach to combating Alzheimer’s, and say they may have found the breakthrough drug that can halt the progress of the disease. In a small clinical trial, researchers tested a drug that targets the tangles of protein that form in the brain cells of Alzheimer’s patients, and found that the drug stopped the cognitive decline of those patients.
Lead researcher Claude Wischik says: “This is an unprecedented result in the treatment of Alzheimer’s disease. We have demonstrated for the first time that it may [be] possible to arrest the progression of this disease by targeting the tangles which are highly correlated with the disease” [CNN]. The results were announced at the International Conference on Alzheimer’s Disease taking place in Chicago.
The cholesterol-lowering drugs known as statins are already one of the most commonly prescribed medications, taken by 15 million Americans in an attempt to ward off heart disease. Now, a new study suggests that the drugs may also reduce the risk of Alzheimer’s and dementia by 50 percent.
While the provocative finding offers hope that the cholesterol-reducing drugs might help against Alzheimer’s disease and other forms of dementia, scientists say this study is unlikely to be the last word on the topic. Indeed, it may just fuel an already lively debate over statins’ potential effect on dementia. Some research has hinted at benefits, while other studies, particularly in people with clear signs of Alzheimer’s disease, show no effect from the drugs [Science News].
Researchers have caught sight of Alzheimer’s-like plaques in the brains of rabbits using a conventional MRI scan, in what could be an important step towards early detection of Alzheimer’s in humans. Researchers say that an earlier, easier diagnosis of the disease would allow patients to try more drugs and other therapies that could slow the progress of dementia.
Diagnosis by a commonly available clinical MRI scan would be a vast improvement over current methods. Many tools are used to look for signs of Alzheimer’s, including a battery of cognitive and behavioral tests… and imaging studies called PET scans that require the injection of special chemicals that help light up the brain. But doctors can make a definitive diagnosis only after a patient dies by identifying the presence of brain lesions called amyloid plaques [USA Today].
In a day of mixed results for Alzheimer’s research, researchers found that an experimental vaccine failed to prevent the disease’s crippling dementia, but also noted that a drug once used to treat hayfever “significantly” improves the symptoms of memory loss. The two separate studies were both published in the Lancet [subscription required], and offer a telling reminder that in medical research progress against a disease is rarely straightforward.
The first study treated patients who had already been diagnosed with Alzheimer’s with a vaccine that targeted the protein plaques that clump around brain cells in increasing numbers as Alzheimer’s progresses. The theory was that dementia could be slowed or reversed once the plaques were cleared [HealthDay News]. However, the vaccine had no effect on the patients’ slide into dementia, despite the fact that autopsies of patients who died during the study showed that the plaques had largely vanished.
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].