Q1. What is the passage mainly about?

1. AHow phone batteries are made
2. BA study about lithium and memory problems
3. CWhy mice like to eat metal
4. DA new medicine that cures memory loss

リチウムと物忘れ（記憶の問題）の関係を調べた研究が全体のテーマなので B。D の「治す薬」は本文にない。

Q2. How many metals did the researchers study?

1. A7
2. B17
3. C25
4. D27

researchers at Harvard studied 27 metals とあるので D。2025 は発表年なので注意。

Q3. In this passage, "clearly lower" means ...

1. Ait was easy to see that the amount was smaller
2. Bthe color of the brain was lighter
3. Cthe brain was cleaner than before
4. Dthe amount was a little higher

clearly は「はっきりと」、lower は「より少ない・低い」。リチウムの量がはっきり少なかったという意味なので A。

Q1. What did the Harvard team discover about people with mild cognitive impairment?

1. ATheir brains had more lithium than usual.
2. BMany different metals in their brains were reduced.
3. CLithium was the only metal clearly reduced in their brains.
4. DTheir brains did not contain any metals.

lithium was the only one that was clearly reduced in people with mild cognitive impairment とあるので C。減っていたのはリチウム「だけ」なので B は誤り。

Q2. According to the passage, why might brain cells have less lithium?

1. ABecause people stop drinking water.
2. BBecause amyloid plaques seem to trap the lithium.
3. CBecause batteries use up the lithium in the body.
4. DBecause the brain produces too much lithium.

amyloid plaques seemed to trap lithium, leaving less for brain cells とあるので B。

Q3. What does the last sentence suggest?

1. APeople should start taking lithium now.
2. BThe mouse results prove that lithium cures Alzheimer's.
3. CLithium is harmful to all mice.
4. DMore research in humans is still needed.

最終文 nobody knows whether this works in humans は、人での効果がまだ分かっていない＝人での研究が必要だということを示すので D。

Q1. What is the main point of the passage?

1. ALithium deficiency may be a new factor in the early stages of Alzheimer's disease.
2. BAmyloid beta and tau are no longer considered important.
3. CLithium orotate has been proven safe for human patients.
4. DMetals in the brain have no link to memory.

The new work suggests that a third factor, lithium deficiency, may also play a role と、新しい視点としてリチウム不足を紹介しているので A。B・C は本文に反する。

Q2. What did the researchers do to test cause and effect?

1. AThey gave lithium to patients with MCI.
2. BThey compared drinking water in different countries.
3. CThey cut the lithium in the brains of mice by about half through diet.
4. DThey removed plaques from human brains.

To test cause and effect, the team cut brain lithium in mice by half through their diet とあるので C。人への投与は行っていない。

Q3. Which limitation of the study is mentioned in the passage?

1. AThe mice did not show any memory changes.
2. BOnly one metal was measured in the brain tissue.
3. CThe study has not been published in a journal yet.
4. DThe human data cannot show whether low lithium is a cause or a result.

tissue examined after death cannot show whether low lithium is a cause or a consequence of the disease とあるので D。死後脳のデータでは因果の向きが決められない、という典型的な限界。