Progress in research on the "Super-agers" elderly whose brains do not become senescent - American university

Recently CNN.co.jp reported the following:

脳が衰えない高齢者「スーパーエイジャー」研究進む　米大学

2022.12.05 Mon posted at 16:15 JST

 （ＣＮＮ） ８０歳を越えても２０～３０歳下の年代と同じ脳の働きを維持している「スーパーエイジャー」たちの研究に、米シカゴのノースウェスタン大学医学部が取り組んでいる。

チームは１４年前から、記憶力の優れた高齢者を募って研究を進めてきた。スーパーエイジャーという専門用語も同大学で誕生した。

８０歳以上の高齢者が詳しい認知機能の検査を受け、５０～６０代の正常な人々と同じかそれ以上の記憶力がある場合に限って、研究対象に入ることができる。特に、日常の出来事や過去の経験をよく記憶していることが条件だという。

応募者の中で条件に合うのはわずか１０％ほど。知能指数（ＩＱ）検査の結果は平均的な高齢者とあまり差がなく、知的レベルだけの問題ではないと考えられる。

対象に選ばれた人々の脳を三次元（３Ｄ）スキャンで調べた後、認知機能の検査と脳スキャンをほぼ毎年繰り返してきた。

ほとんどの人は年を取ると脳が委縮していくが、チームによると、スーパーエイジャーでは思考や判断、記憶をつかさどる大脳皮質の厚みが変わらず、５０～６０代に比べて脳萎縮のペースも遅いという。

スーパーエイジャーの脳は本人の意思で死後に寄付されることが多い。それを調べると、アルツハイマー病で最初にむしばまれる領域のひとつである「嗅内野」に、より大きく健康な細胞が多いことが分かる。

嗅内野は記憶と学習に欠かせない領域で、記憶保持を担うもうひとつの主要な領域「海馬」と直接つながっている。

亡くなったスーパーエイジャーの脳を年上や年下の正常なグループ、初期のアルツハイマー病と診断されたグループと比べ、研究結果を今年発表した同大学の准教授によると、スーパーエイジャーでは神経細胞に蓄積してアルツハイマー病などの認知症を引き起こす「タウたんぱく質」の量が、健康なグループの３分の１しかなかった。

スーパーエイジャーの脳では、脳内の素早い情報伝達に役立つとされる紡錘（ぼうすい）形の細胞「ＶＥＮ」の数が多いことも分かった。ＶＥＮがある「前帯状皮質」は、情緒のコントロールや注意力に重要な役割を果たすと考えられている。

これらの研究結果からうかがえるのは、スーパーエイジャーになるかどうかに遺伝的因子が絡んでいるということだ。ただ確認するには、対象者が生まれてから死ぬまで神経細胞の大きさなどを測り続ける必要があり、それは明らかに不可能だ。

チームによると、スーパーエイジャーに共通するのは活動的かつ前向きで、毎日脳を刺激し、読書をしたり新たなことを学んだりしているという特性だ。社交的で家族や友人に囲まれ、地域のボランティア活動にも積極的に参加することが多いという。

Translation

(CNN) Northwestern University School of Medicine in Chicago had been working on the study of "Super-agers," who were over 80 years old still maintaining the same brain function as those 20 or 30 years younger.

For the past 14 years, the research team had recruited elderly people with excellent memory. The term “Super-ager” was also born at the same university.

Included in the study were those aged 80 and over who had undergone detailed cognitive function tests, and limited to those who had the same or better memory than normal people in their 50s and 60s. In particular, as a condition, had a good memory of everyday events and past experiences.

Only 10% of applicants met the criteria. Their intelligence quotient (IQ) test results were not much different from those of the average elderly person, suggesting that it was not just a matter of intellectual level.

After performing three-dimensional (3D) scans of the brains of selected subjects, cognitive tests and brain scans were repeated almost every year.

Most people's brains shrank as they get older, but according to the team, the thickness of the cerebral cortex, which controls thinking, judgment, and memory, remained the same in Super-agers, and the rate of brain shrinking among them was slower than in people in their 50s and 60s.

A Super-ager's brain was often donated posthumously, voluntarily. Examination revealed that in the entorhinal cortex, one of the first areas to be eroded in Alzheimer's disease, we could see many larger and healthier cells.

The entorhinal cortex was essential for memory and learning, and was directly connected to another major area of memory retention, the hippocampus.

After comparing the brains of deceased Super-agers with older and younger normal groups, and also those who had been diagnosed with early-stage Alzheimer's disease, an associate professor at the university who published the results earlier this year had found that the amount of “tau protein” found accumulated in neurons of Super-agers was only one-third that of the healthy groups, tau protein could cause dementia such as Alzheimer's disease.

It was also found that the brains of Super-agers had a large number of spindle-shaped cells known as VEN, which were said to help speed up the transmission of information within the brain. The "anterior cingulate cortex," where VEN located, was thought to play an important role in controlling emotion and focus.

These findings suggested that genetic factors played a role in whether a person becomes a Super-ager. However, in order to confirm this, it was necessary to continuously measure the size of nerve cells and other factors from the time the subject was born until they died, and this was clearly impossible.

According to the team, Super-agers in common were active and forward-looking, stimulated their brains every day, shared the traits of doing reading and learning new things. They were sociable, surrounded by family and friends, and often actively participated in community volunteer activities.

              So, clinically, Super-agers' brain have larger and healthier cells in the entorhinal cortex. Also, the amount of “tau protein” found accumulated in their neurons is less than normal people, and their brains have a large number of spindle-shaped cells known as VEN. Outwardly, Super-agers are active and forward-looking, share the traits of doing reading and learning new things. They are sociable, surrounded by family and friends, and often actively participate in community volunteer activities.