When true psychic attack is underway, the onset will be sudden and severe, seemingly out of the blue:
Severe fatigue and the inability to recover strength easily. Intense fearfulness and paranoia that is not common to the personality.
Anxiety attacks/Panic attacks
Nightmares, particularly of being chased or someone/ something trying to kill the victim.
One part of the body or the whole body being extremely and unreasonably cold.
Severe pain or tension in the solar plexus, stomach, or intestinal area.
Unexplainable depression that cannot be shaken off.
Feelings of suicide or self-harm untraceable to any genuine issue.
Shaking and trembling.
Extreme pessimism and a sense of hopelessness.
Loss of self confidence in a normally self-assured person.
Abrupt onset of a “victim” mentality.
Unexpected severe health problems.
Basically, what you are looking for is an abrupt change in personality and often, the victim using words or phrases that are atypical to their usual form of experson. Often it is someone around the victim who first suspects psychic attack because to the victim their own thoughts processes seem organic and make person sense.
Magical Ethics and Protection(Book 4)
Katrina Rasbold ; Eric Rasbold