The most typical signs of the paranoid personality disorder include:
Inability to forgive or forget something bad;
Desire to focus on bad aspects of life instead of seeing something good;
Unwillingness to value what they have;
Belief that other people are using them;
No trust in such traits as loyalty or credibility;
No friends of partner for a long period of time;
Inability to take fair criticism and improve correspondingly;

Tendency to get angry or even fall in rage each time someone says something they dislike or acts in a wrong manner;
Desire to notice hidden messages in the remarks that are not worth taking them seriously; do not understand some sort of jokes;
Suspicious sense without any good reason;
Frequent conflicts with people around;
Strong desire to stay alone for a while; denial of any sort of relationships;
Feeling jealous and envious too often and without reasons;
Unwillingness to understand their true role in some life situations and fix own mistakes;
Lack of relaxation and sleep.

Causes of the paranoid personality disorder. It is hard to tell the exact causes of various mental diseases unless the person had to go through some really stressful or shocking situation. A powerful shock might be the reason for the individual to behave weirdly for the rest of his or her life. Doctors stress there are three factors important to consider when trying to realize why PPD happened to someone: biological, psychological, social.