アルツハイマー病モデルマウスの脳神経細胞を刺激することで失われた記憶を取り戻すことに成功したと、理化学研究所の利根川進(とねがわ すすむ)・脳科学総合研究センター長(マサチューセッツ工科大学教授、理研-MIT神経回路遺伝学研究センター長)らの研究グループが17日発表した。アルツハイマー病患者は、記憶そのものが失われるのではなく思い出す機能が働かなくなっている可能性を示唆し、初期症状の「物忘れ」の仕組み解明につながる、と期待される。論文は英科学誌ネイチャー電子版に掲載された。
研究グループは、アルツハイマー病患者と同じ神経変性を示すモデルマウスをつくった。モデルマウスと正常マウスをそれぞれ実験箱に入れ、電気刺激を与えて不快な体験として記憶させた。モデルマウスには、刺激を与えた時に働いた脳神経細胞に目印を付けておいた。実験の後に箱から出し、翌日にモデル、正常それぞれのマウスを再び実験箱に戻した。
すると、正常マウスはおびえる様子を見せたが、モデルマウスの様子に変化はなく記憶障害を起こしているとみられた。このため、目印を付けていた脳神経細胞に光の刺激を与えてこの神経細胞を働くようにしたところ、モデルマウスは正常マウスと同じようにおびえた、という。
この結果について研究グループは「実験からモデルマウスは、記憶は正常に形成し、保存しているが、想起できなくなっている可能性があることが分かった」としている。記憶に関係する神経細胞を刺激すると、神経細胞回路のつながりが強まり、記憶をある程度取り戻したとみられる。
アルツハイマー病は、認知症の中でも最も多く、患者の脳には「アミロイドベータ」と呼ばれるタンパク質が異常な形で蓄積することが分かっている。「物忘れ」から始まり徐々に認知機能全体が低下していく。国内患者は90万人以上とされ、軽度の症状を含めると400万人にも及ぶとの推計もある。一方さまざまな医学分野での研究も進み、薬で進行が抑えられた症例も増えているが、根本的な治療方法はまだ確立されていない。
・2014年4月25日ニュース「間違いを自己修正する脳の仕組み発見」
・2014年4月14日ニュース「アルツハイマー病の新しいマウス作製」
アルツハイマー病のリスクを下げる、7つの食べ物
1. Walnuts (And Almonds, Pecans, Hazelnuts) (01 of07)
Open Image ModalWalnuts might be small in size, but they pack a big nutritional punch. They are filled with Omega-3 fatty acids, the good kind of fat your brain needs. A study from the New York State Institute for Basic Research in Developmental Disabilities found that mice given a diet including walnuts showed improvement in memory and motor coordination. Walnuts also contain vitamin E and flavonoids, which can help protect the brain. (credit:Shutterstock)
2. Salmon (And Mackerel, Sardines, Other Fatty Fish)(02 of07)
Open Image ModalAlso high in Omega-3s, fatty fish like salmon can lower blood levels of beta-amyloid, a protein thought to play a role in Alzheimer’s. A Columbia University study found that the more Omega-3 fatty acids a person eats, the lower their blood beta-amyloid levels. Dr. Nussbaum suggests eating 8 oz. of fish per week—fresh fish is best, but you can also talk to your doctor about taking a fish oil supplement. (credit:Shutterstock)
3. Berries (03 of07)
Open Image Modal“Antioxidants are like taking out the broom in the spring and sweeping the garage,” Dr. Nussbaum says. “Antioxidants are the body’s broom.” Berries contain polyphenols, a type of antioxidant which helps stop inflammation and allows brain cells to work better. A Tufts University study found that berries can reverse slow-downs in the brain’s ability to process information. \n\n“You can’t go wrong if a food has the word ‘berry’ in the name,” says Dr. Nussbaum. “Strawberries, blueberries, cranberries— they’re all good for your brain.” (credit:Shutterstock)
4. Spinach (And Kale, Other Leafy Greens) (04 of07)
Open Image ModalFull of antioxidants and fiber, leafy greens should be a diet staple. In a national study, women in their 60s who ate more leafy vegetables over time did better than their non-greens-eating counterparts on memory, verbal, and other tests. And new studies show that high levels of vitamin C, which is found in spinach, may help with dementia prevention. (credit:Shutterstock)
5. Turmeric(05 of07)
Open Image ModalBreak out the curry! A host of studies have shown that turmeric, the spice used in curries, and its main active component curcumin, can help prevent Alzheimer\'s. In one such study, researchers from UCLA found that vitamin D3, taken with curcumin, may help the immune system to get rid of the amino acids that form the plaque in the brain that\'s associated with Alzheimer’s Disease. So the next time you cook, incorporate this healthy spice. (credit:Shutterstock)
6. Coffee (06 of07)
Open Image ModalNow you don’t have to feel guilty about pouring yourself another cup. Researchers from the University of South Florida and University of Miami found that people older than 65 who drank three cups of coffee a day (i.e. had higher blood levels of caffeine) developed Alzheimer\'s disease two to four years later than their counterparts with lower caffeine levels, and that caffeine had a positive impact even in older adults who were already showing early signs of Alzheimer\'s. (credit:Shutterstock)
7. Chocolate (07 of07)
Open Image ModalIf you haven’t already switched from milk chocolate to dark, now you have one more reason to. Compelling research already shows that dark chocolate, which contains flavonoids (a plant compound that helps with the body’s circulation), can help combat heart disease, but flavonoids may also help slow down the effects of dementia. In an Italian study, older adults who had mild symptoms of dementia drank cocoa with high, medium and low amounts of flavonoids. Those who consumed high amounts outperformed those who consumed low doses on cognitive tests.\n\n\nAnd a study is currently underway by the National Institute on Aging to see whether resveratrol, a compound found in chocolate, red wine, and grapes, can prevent dementia. One tip: A healthy choice is dark chocolate that has a 70% or higher cocoa content. (credit:Shutterstock)