expression, noun
mental illness; emotional disorder
A somewhat literary or formal expression for mental or emotional illness. It is rare; in modern everyday speech, 精神病 or メンタルヘルスの問題 are more common.
彼は長年、心の病に苦しんでいた。
He suffered from a mental illness for many years.
心の病は、誰にでも起こりうるものだ。
Mental illness can happen to anyone.