Why does BPD present with other mental illnesses?

[VIDEO: "What is parental alienation?"]

I just read that BPD often presents with other diagnoses such as depression, anxiety, bipolar, and ADD and ADHD.

Why is that? What is the pathway here? 

[FeelingBitter]

I just read that BPD often presents with other diagnoses such as depression, anxiety, bipolar, and ADD and ADHD.

Why is that? What is the pathway here? 

[borderlinebunny]

BPD is so centered around our moods, intense reactions, and general low ability to function in life, relationships, jobs, etc, in a healthy way that it gives way to things like anxiety and depression. With every avenue of our lives being affected by BPD, it's easy for other problems to come into play possibly as a result of living the consequences of our actions. Our negative, destructive behavior is "natural" to us, but it's very easy for people to react with upset or even aggression in return, thus making us feel worse, thus contributing to anxiety.

Also, keep in mind that the very development of BPD in the first place, can stem from things like physical and mental abuse, sexual abuse, neglect, and personal invalidation (of feelings, thoughts, interests, etc), in childhood. These things are likely just as responsible for the onset of things like depression and anxiety as the BPD itself.

[FeelingBitter]

BPD is so centered around our moods, intense reactions, and general low ability to function in life, relationships, jobs, etc, in a healthy way that it gives way to things like anxiety and depression. With every avenue of our lives being affected by BPD, it's easy for other problems to come into play possibly as a result of living the consequences of our actions. Our negative, destructive behavior is "natural" to us, but it's very easy for people to react with upset or even aggression in return, thus making us feel worse, thus contributing to anxiety.

Also, keep in mind that the very development of BPD in the first place, can stem from things like physical and mental abuse, sexual abuse, neglect, and personal invalidation (of feelings, thoughts, interests, etc), in childhood. These things are likely just as responsible for the onset of things like depression and anxiety as the BPD itself.

That makes total sense. Thank you!