senile

我的祖父开始出现记忆力减退等衰老症状。

My grandfather is showing signs of ___senile memory loss.

他的老年症状包括经常忘记钥匙放在哪里。

His ___senile symptoms include frequently forgetting where he left his keys.

我的祖母开始变得有些糊涂，经常忘记把钥匙放在哪里。

My grandmother is getting ___senile and often forgets where she puts her keys.