It's right out of the diagnostics and statistical manual.

出自。

Although the decision that someone's worry is excessive and unreasonable has a subjective quality, diagnosing GAD is aided by the diagnostic and statistical manual of mental disorders, or DSM-V.

不过，判断一个人担忧过度且不合理是比较主观的，对于GAD的诊断可借助《美国精神障碍诊断与统计手册》，即DSM-5。