Paranoid personality disorder (PPD) is one of a group of conditions called "Cluster A" personality disorders which involve odd or eccentric ways of thinking. People with PPD also suffer from paranoia, an unrelenting mistrust and suspicion of others, even when there is no reason to be suspicious.

This disorder usually begins by early adulthood and appears to be more common in men than in women.

People with PPD are always on guard, believing that others are constantly trying to demean, harm, or threaten them. These generally unfounded beliefs, as well as their habits of blame and distrust, might interfere with their ability to form close relationships. People with this disorder:

• Doubt the commitment, loyalty, or trustworthiness of others, believing others are using or deceiving them
• Are reluctant to confide in others or reveal personal information due to a fear that the information will be used against them
• Are unforgiving and hold grudges
• Are hypersensitive and take criticism poorly
• Read hidden meanings in the innocent remarks or casual looks of others
• Perceive attacks on their character that are not apparent to others; they generally react with anger and are quick to retaliate
• Have recurrent suspicions, without reason, that their spouses or lovers are being unfaithful
• Are generally cold and distant in their relationships with others, and might become controlling and jealous
• Cannot see their role in problems or conflicts and believe they are always right
• Have difficulty relaxing
• Are hostile, stubborn, and argumentative