Although not necessarily indicative of mental disturbance, these actions, or signs of trouble, can sometimes help you identify someone who needs help:
ACTING DIFFERENT THAN USUAL. Can you link this change in behavior to something that has happened recently? Any event, such as the death of a close relative, or even something positive – like a job promotion – can trigger a troublesome emotional reaction.
SEEMS TO BE EXCESSIVELY WITHDRAWN AND DEPRESSED. Are hobbies, friends and relatives ignored suddenly? Is there a feeling that this person has begun to lose self-confidence? Depressive illnesses have many symptoms similar to these.
COMPLAINS OF EPISODES OF EXTREME, ALMOST UNCONTROLLABLE, ANXIETY. Is this anxiety unrelated to any normal concern, such as a child’s illness, a backlog of bills? Anxiety that has no discernible cause is a sign of an emotional difficulty.
BECOMES AGGRESSIVE, RUDE, AND ABUSIVE OVER MINOR INCIDENTS. Are there remarks about groups or individuals “out to get me?” If that last remark was made in all seriousness, and blowups and violent physical behavior occur, there is a strong indication some help may be required.
A CHANGE IN THE PERSON’S HABITS, SUCH AS EATING, SLEEPING OR GROOMING. Suddenly, has the individual almost stopped eating? Conversely, has he or she started eating or drinking a lot in a compulsive manner? Either sleeplessness or too much sleeping can be indicators, if they are done to excess.
Any of these signals, if they continue for any length of time, may call for professional help. Fortunately, early identification of the underlying problems causing the behavior can often make symptoms disappear.
Source – NIMH