Dementia is an illness of the brain. Memory gets weaker, and little by little the person finds it harder to think, plan, talk, and look after themselves in the old way.

Dementia失智症 is an illness of the brain是一種腦部的疾病。Memory記憶 gets weaker會漸漸變差, and little by little一點一點地 the person當事人 finds it harder to think, plan, talk, and look after themselves in the old way會變得比較難用原本的方式思考、規劃、說話，還有照顧自己

It is not one single disease; several illnesses can cause it. Alzheimer’s is the one people hear about most. It usually comes on slowly, more often in older age, though not only then.

It它 is not one single disease不是單一一種疾病；several illnesses好幾種疾病 can cause it都可能造成它。Alzheimer's阿茲海默症 is the one people hear about most是大家最常聽到的一種。It它 usually通常 comes on slowly是慢慢出現的, more often in older age年紀較大時比較常見, though not only then但不是只有那時候才會

Doctors use dementia as a careful medical word. Families often say “losing their memory” in kind everyday talk.

Doctors醫生 use使用 dementia「dementia」這個字 as a careful medical word當作嚴謹的醫學用語。Families家人 often常常 in kind everyday talk用溫和的日常說法 say說 'losing their memory'「記憶力變差了」

Though actually, casual English also uses demented to mean “wild” or “crazy,” as a joke or an insult. That loose use is not this illness, and it can hurt. The medical word is about a real change in the brain, not about a person being silly or difficult on purpose.

Though actually不過實際上, casual English日常口語的英文 also uses也會用 demented「demented」這個字 to mean "wild" or "crazy,"來表示「瘋狂」或「誇張」的意思, as a joke or an insult當作玩笑或罵人的話。That loose use這種鬆散的用法 is not this illness不是指這種病, and it can hurt而且可能會傷人。The medical word這個醫學用語 is about a real change in the brain說的是腦部真正發生的變化, not about a person being silly or difficult on purpose不是說一個人故意耍笨或找麻煩