How young can a person be diagnosed with ptsd?

There is no age: Criterion for diagnosing ptsd. A person of any age who experiences a serious trauma and then exhibits symptoms of re-experiencing, avoidance or emotional numbing, and increased arousal would meet the requirements for ptsd. Obviously, a pre-verbal child will not be able to report the trauma, and symptoms may be more difficult to interpret in a young child.

PTSD : There is no clearly defined age restriction, but it is safe to say that even very young children who are victims of traumatic experiences can be diagnosed with ptsd.

Formal assessment: I agree with dr. Stewart. There are no age specific criteria. If there is a concern about the possibility of ptsd, recommend assessment by a child fellowship trained psychologist or psychiatrist who has specific experience with ptsd.