if they speak to themselves.
It can be even more subtle than that. It depends on the mental disorder they have. They could become withdrawn, quite, suddenly angry or sad, and so on. If anyone shows any of these signs it is best to get them help. It could always be something simple. But if not it could lead to suicide or drugs or even alcohol. There are many sites you can go to find the answers you may be looking for. However, when in doubt consult a physician in the Mental Health field.
ask them
No
YOU can't tell them. A mental health professional has to asses and diagnose them.
Mental illnesses are mostly genetic. If there are no genetic markers then the chances of someone experiencing a mental illness sometime in their lives is not likely. If symptoms are present a doctor should be contacted immediately.
The word psychological describes someone's mental or emotional state. This term is used when someone has a mental illness instead of a physical ailment.
No. That's called fantasy.
The term "mental illness" refers to someone who has a mental (brain) related deficiency. Some of these mental illnesses affect your mood, behavior or actions.
In order to know how should they talk to the clients with special needs or a mental illness and if they are supposed to be with clients all day or in the office one needs to know who you are referring to.
Sinusitis is not caused by mental illness. Mental illness can be caused by sinusitis infection.
not guilty by reason of mental illness
Mental illness predates recorded history.
If, by your question, you mean is there a way to determine whether someone is mentally ill secondhand, that is, by talking to a friend or relation of the person in question, then the answer is no. Mental illness can only be diagnosed through interviewing and testing the person in question directly. It is generally pretty easy to know when someone is in need of psychotherapy, but the only way to diagnose what the illness might be is by a personal interview.