This is a really great summary in my opinion. Having the 2 conditions with Bipolar has been like having big huge tides, in & out, high & low that last for months whist simultaneously high winds & daily storm conditions wreck small boats & drown their strewn crew in frothing waters.
By: Sarah Fader
Updated March 05, 2020
Medically Reviewed By: Whitney White, MS. CMHC, NCC., LPC
Many people find borderline personality disorder hard to understand. A common question is 'On the borderline of what?' The meaning of the name isn't as obvious as with some personality disorders, like antisocial or avoidant. The best way to understand borderline personality is to examine the DSM-5, the current diagnostic manual for mental disorders.ders.

Source: rawpixel.com
What Is the Borderline in BPD?
The term 'borderline' in BPD is an early name given to the disorder as it was understood when it was first described in 1938. People with borderline personalities were thought to be on the borderline of a treatable neurosis and the psychotic disorder schizophrenia.
However, since the 1970s, further investigation into the disorder has revealed that this old name is inadequate to describe it. The name still stands, but the debate continues in the psychiatric community. The most important thing to remember about borderline is that it is an old, outdated term that simply hasn't yet found its replacement.
What Is a Personality Disorder?
The first part of the borderline personality disorder definition you need to remember is that it is a personality disorder. All the traits and behaviors that accompany BPD are rooted in the personality.
About 30% of people who need mental health care have one or more personality disorders. Someone with a personality disorder has problems with their self-concept and trouble relating to other people in healthy ways. Anyone might have thoughts or behaviors that typify a personality disorder. If these behaviors only happen once or rarely, they are not a part of a disorder, but might instead be a reaction to a situation. That's because the personality is fixed even when circumstances change. Successful treatment of personality disorders is possible. It doesn't cure the disorder but can dramatically reduce its symptoms.
What About Borderline Personality?
Borderline personality disorder is one of 9 types of personality disorders. To fully define borderline personality disorder, you need to include the specific thoughts and behaviors that go along with this personality disorder. The two basic types of problems associated with BPD are an unstable sense of self and dysfunctional interpersonal relationships. Both components of the disorder show up in thoughts and behaviors.
Unstable Sense of Self
Poor Self-Image - People with BPD don't see themselves as others do. Their self-concept may be extremely distorted and is usually negative. They usually have periods of high self-confidence followed by periods of low self-esteem
Trouble Directing Yourself - If you have borderline personality disorder, you probably have trouble making concrete plans and following through with them. Your career path may be a jumble of false starts and lengthy detours. You may tend to let others or circumstances determine your course in life, because you don't stick with one goal to its completion.
Impulsive and Self-Damaging Behaviors - Dangerous behaviors are common with BPD. The person with this disorder might drive recklessly, go on wild spending sprees, have unprotected sex, abuse drugs and/or alcohol, binge eat, or impulsively take part in any other dangerous behavior. They may also threaten, attempt suicide, or engage in self-harm.

Source: pexels.com
Intense and Quickly-Changing Moods - Unlike familiar mood disorders such as bipolar or schizoaffective, borderline personality disorder features intense moods that nearly always change in a few days or even hours. Many people with BPD also suffer from anxiety, depression, or both.
Feeling Empty or Angry - A pervasive feeling of emptiness often goes along with BPD. Anger can also boil up quickly, and the person with borderline personality disorder usually has a tough time controlling it. The thing the person becomes angry about may be quite trivial to anyone else, but to him or her it's enough reason to become angry and hostile.
Paranoid Thoughts When Stressed - Paranoia can be a problem. It typically comes up only when stressed. However, because of poor self-esteem and interpersonal problems, stress may occur more often.
Dissociating When Stressed - One of the most extreme manifestations of BPD is the dissociative state that can happen when the person is under stress. They can lose touch with reality and even see themselves as if from the outside.
Interpersonal Difficulties
Abandonment Issues - People with borderline personality typically fear abandonment to such a degree that they are desperate and even panicky in their efforts to avoid it. Efforts to avoid abandonment can often lead to the very relationship loss they hope to avoid.
Unstable Relationships - For someone with BPD, relationships are both intense and unstable. This is partly due to experiencing the relationship in extreme terms, as the person vacillates between idealizing it and criticizing it. Another problem with relationships is that fear of abandonment leads to clinginess or pushing others way to avoid eventual rejection.
Anger Management Problems - Since extreme, sudden, and frequent anger is often a part of borderline personality, those who haven't learned how to control their anger can get into trouble. They may get into physical fights to the extent that their actions constitute assault. Criminality related to anger isn't uncommon.
Of course, the excessive anger isn't conducive to healthy interpersonal relationships such as marriage or parenthood. Those with BPD may get over anger quickly, but in some cases, this is after damage is already done to relationships.
Misinterpreting Facial Expressions - Borderline personality disorder features a tendency to see negative emotions where others don't. The person they are interacting with may not be expressing any emotion at all, but people BPD tend to see sadness, disgust, anger or fear when they look at another's face. This almost invariably leads to further interpersonal problems, because they base their behaviors on faulty interpretations.