「バイリンガルは認知症が4年遅れる」は本当？ 話題の研究とその後の反論

Q1. What did the 2007 study find?

1. ABilingual people never got dementia.
2. BBilingual people got symptoms about four years later.
3. CBilingual people got dementia four years earlier.
4. DLearning English cures dementia.

People who spoke two languages got symptoms about four years later. とあるので B。

Q2. What did studies of healthy people find?

1. ANobody got dementia.
2. BBilingual people got dementia more often.
3. CHealthy people stopped speaking two languages.
4. DBilingual people did not get dementia less often.

They found that bilingual people did not get dementia less often. とあるので D。

Q3. In this passage, "prevent" means ...

1. Amake something happen faster
2. Bfind something
3. Cstop something from happening
4. Dstudy something

prevent は「防ぐ・起こらないようにする」。delay（遅らせる）との対比で使われているので C。

Q1. What was special about the 2013 study in India?

1. AIt followed healthy people for many years.
2. BIt found no delay at all.
3. CIt only studied doctors.
4. DThe delay was found even among people who could not read or write.

even among people who could not read or write とあるので D。教育だけでは説明しにくいことを示す。

Q2. How were the 2007 and 2013 studies different from later studies?

1. AThey looked back at patients who already had dementia.
2. BThey used brain scans.
3. CThey studied only children.
4. DThey found that bilinguals had a higher risk.

these studies looked back at patients who already had dementia とあり、後の研究は健康な人を前向きに追跡したので A。

Q3. According to the idea of cognitive reserve, what might bilingual experience do?

1. ALower the risk of getting dementia
2. BHelp the brain hide symptoms for longer
3. CMake dementia start earlier
4. DReplace the need for education

may help the brain hide symptoms for longer without lowering the risk itself とあるので B。

Q1. What weakness of the retrospective studies does the passage point out?

1. AThey included too many healthy people.
2. BThey often relied on relatives' memories to date the onset of symptoms.
3. CThey were conducted only in Canada.
4. DThey measured risk instead of onset.

often relied on relatives' memories to date when symptoms began とあるので B。発症時期の正確さに限界がある。

Q2. What does an odds ratio of 0.96 suggest?

1. ABilinguals have a much lower risk.
2. BBilinguals have twice the risk.
3. CThere is essentially no difference in risk.
4. DThe study failed to include bilinguals.

an odds ratio of 0.96, which is essentially no difference と言い換えられているので C。

Q3. Why does the author say the two results "need not conflict"?

1. ABecause immigration has no effect on dementia.
2. BBecause all the studies used the same patients.
3. CBecause the 2007 study was later withdrawn.
4. DBecause bilingualism might delay symptoms without changing the underlying risk.

認知予備力仮説では、脳が損傷に長く持ちこたえ、That would push back the first symptoms without lowering the risk of disease. となるので D。