There are the A-Z lists APD, DPD, BPD, and NPD, of Personality Disorders, I don't want to box anyone into a label or stigma based on what you or I might think is the behavior causing harm. Let's explore what your behavior looks like.

Below are a couple most often identified with - 

Borderline Personality Disorder (BPD) 

Borderline personality disorder (BPD) is also a Cluster B personality disorder. It is characterized by consistent changes in behavior, mood, and self-image. Episodes of anger, depression, and anxiety lasting up to a few days are common for people with BPD.2

People with BPD frequently change their opinion of themselves and others and their interests. Drastic changes in opinion often lead to tumultuous or unstable relationships with others. Other symptoms of BPD include:

• Extreme fear of abandonment
• Impulsive behaviors (such as unsafe sex or substance use)
• Self-harm
• Thoughts of suicide

Especially during times of stress, people with BPD can experience dissociation. Someone experiencing dissociation can feel like they don't have a sense of self or identity.3 They can feel detached from their emotions, memories, and thoughts. They can also experience significant memory loss of times in their life, people, and events.

What is Narcissistic Personality Disorder?

So, what is narcissistic personality disorder (NPD)? Like borderline personality disorder, the Diagnostic and Statistical Manual of Mental Disorders (DSM) lists nine common symptoms of narcissistic personality disorder. If an individual exhibits five of these nine symptoms consistently, they meet the criteria for an NPD diagnosis.

An exaggerated sense of one’s own abilities and achievements

A constant need for attention, affirmation, and praise

A belief that you are unique or “special,” and should only associate with other people of the same status

Persistent fantasies about attaining success and power

Exploiting other people for personal gain

A sense of entitlement and expectation of special treatment

A preoccupation with power or success

Feeling envious of others, or believing that others are envious of you

A lack of empathy for others

How Often NPD and BPD Co-Occur

While the overlap between NPD and BPD is discussed often in the popular psychology literature and online, very few careful studies of the co-occurrence of NPD and BPD have been conducted. One older study reported that almost 39% of people with BPD also have NPD

Another 2018 study showed a strong correlation between BPD and a certain type of narcissism: vulnerable narcissism, which is characterized by hypersensitivity, defensiveness, and low self-esteem. The same study also found that male patients had higher narcissistic scores than female patients.

How NPD Affects BPD

There are a number of theoretical reasons to believe that someone with both NPD and BPD would be less likely to get better over time. People with NPD can be resistant to treatment, and often have poor insight into the ways that their behaviors are detrimental to themselves or others.

Also, people with NPD may cause more emotional pain to others than they cause themselves. This can mean that their motivation to change their behavior is very low.

One study that followed BPD patients over six years found that rates of co-occurring NPD were fairly low, about 6%, in patients whose BPD eventually went away (remitted).

However, rates of co-occurring NPD were higher (around 19%) in patients whose BPD did not remit after six years.So there is a subset of people with non-remitting BPD and higher rates of NPD.

NPD and BPD in Relationships 

The relationships of people with BPD are often quite dysfunctional. Adding NPD into the mix can create even more disordered conditions. One study notes, for example, that as the severity of NPD increases, so does aggression (directed at oneself or others) and difficulty withinterpersonal behavior and moral functioning.

In addition to the chaotic emotional life and fears of abandonment associated with BPD, a person with co-occurring NPD may also take advantage of or manipulate others while having little empathy for others' concerns. This combination can be incredibly destructive in relationships.

If you are in a relationship with someone who has BPD, NPD, or both, encourage them to seek treatment. Individual therapy for each partner, along with couples' therapy, may help you both cope with the symptoms of personality disorders that make relationships difficult.