• A lack of trust in others
• Feeling suspicious of others' motives
• Appearing detached and unfriendly
• Being isolated from others, often by choice
• Denial of responsibility for one's actions
• Acting out in aggressive or abusive ways
• Lacking confidence
The Merck Manuals Online Medical Library does report that people with paranoid personality disorder are sometimes very effective and productive, due to their isolated nature. However, this disorder usually causes more problems than positive symptoms.