If you know someone who is always suspicious and holds grudges, they may have PPD

• Paranoid personality disorder (PPD) causes extreme suspicion and fear of others.
• People with PPD may falsely believe that others are lying, cheating, or exploiting them.
• PPD may develop because of genetics, life experiences like abuse, or other mental health conditions.

Paranoid personality disorder (PPD) is a mental health condition that can cause extreme mistrust and fear of other people, according to the Diagnostic and Statistical Manual of Mental Disorders.

PPD is somewhat rare — between 2.3% and 4.4% of Americans are thought to have the condition.

There is still very little research on paranoid personality disorder and the best way to treat it, but some types of psychotherapy may help.

Here are the most common symptoms of PPD and the best way to manage it.

What is paranoid personality disorder?

"People with this diagnosis tend to be suspicious and mistrustful of other people, tense and nervous in social situations, and on the lookout for threat," says Chris Hopwood, PhD, a professor of psychology at University of Zurich.

They tend to have trouble keeping up friendships and romantic connections, and may be easily insulted or offended.

"People with PPD are outwardly hostile and may seem aloof" because they experience relationships as a source of stress, says Royce Lee, MD, a professor of psychiatry and behavioral neuroscience at the University of Chicago.

Some of the common symptoms of PPD include:

• Believing that other people are lying or exploiting them
• Holding grudges or refusing to forgive
• Being overly sensitive to criticism
• Being afraid to reveal any personal information to other people
• Falsely thinking that other people are insulting them
• Always suspecting that their partner is cheating on them
• Assuming there are hidden meanings in other people's casual remarks or looks
• Having a hard time relaxing
• Being easily angered and quick to argue

People with PPD have a hard time connecting with other people, but that doesn't mean they're dangerous. "They can be prone to anger, but are not necessarily violent," Lee says.

The causes of paranoid personality disorder

There are several different factors that can put you at greater risk of developing paranoid personality disorder. This includes:

Genetics: The disorder tends to run in families and you may be more likely to develop PPD if you have family members with schizophrenia or delusional disorder.

Certain life experiences: "It seems likely that experiences in which a person learns that they cannot trust important people in their environment may be factors," Hopwood says.

According to Lee, some experiences that are linked to PPD include:

• Experiences of racism
• Poverty
• Immigration
• Childhood abuse

Other mental health conditions: In most cases, people with PPD will also have another mental health diagnosis. Commonly linked disorders include:

• Post-traumatic stress disorder
• Anxiety disorders
• Schizophrenia
• Other personality disorders

Diagnosis and treatment

"Paranoid personality is ideally diagnosed with standardized questionnaires or interviews, based on criteria in the diagnostic manual (DSM-5)," Hopwood says.

An important part of this process is to differentiate between PPD and other disorders that have similar symptoms, says Hopwood. For example:

• PPD vs. anxiety: PPD is different from anxiety because the feelings of paranoia are always present, not just in certain situations.
• PPD vs. schizophrenia: PPD is different from psychotic disorders like schizophrenia because there are no hallucinations or delusions. This is an important distinction, because PPD is treated with psychotherapy, while schizophrenia requires medications, Lee says.

However, it's important to note that there is very little research on what qualifies as PPD. In fact, "many clinicians do not think of paranoid personality disorder as a valid category or diagnosis," Hopwood says.

We also have little scientific evidence about the best way to treat PPD, though some experts believe that therapy can help. In particular, some may use cognitive-behavioral therapy, an approach that aims to challenge problematic thoughts and shift behaviors.

There are no medications that can fully treat PPD, but certain antipsychotic medications may help treat anxiety symptoms.

Insider's takeaway

Paranoid personality disorder can cause intense distrust of other people and may make having close relationships very difficult. If you think you may have symptoms of PPD, reach out to a mental health provider to find a treatment plan that works for you.