WHAT IS BPD?
BPD and Co-Occurring Conditions
Borderline personality disorder rarely stands alone. Many individuals experience multiple co-occurring disorders, which increases the complexity of treatment and contributes to varied presentations. These overlapping conditions help explain why people with BPD often receive multiple diagnoses over time.
Understanding Co-Occurrence
In addition to the many possible combinations of BPD symptoms themselves (a minimum of 5 out of 9 DSM criteria), BPD is often present alongside other mental health conditions. This significantly increases the complexity of treatment and can make progress slower or less predictable.
People often carry multiple diagnoses because symptom patterns overlap. Common co-occurring conditions include:
- Depression
- Anxiety disorders
- PTSD or Complex PTSD
- Eating disorders
- Substance use disorders
This does not necessarily mean that separate conditions are operating independently. More often, these diagnoses reflect interacting patterns linked to chronic emotion dysregulation.
This table represents how often other conditions occur when BPD is present:
| Co-Occurring Conditions | |
| Anxiety | 90% |
| Major Depressive Disorder | 85% |
| Eating Disorders (anorexia/bulimia) | ~25% |
| Substance Use Disorders | 35% |
| Bipolar I Disorder | 10% |
| Antisocial PD | ~25% |
| PTSD | 25-40% |
This table represents how often BPD occurs when another condition is present:
| Other Disorders Plus BPD | |
| Major Depressive Disorder | 15% |
| Bulimia | 20% |
| Anorexia | 20% |
| Substance Use Disorders | 10% |
| Other Personality Disorders | 50% |
Interpreting the Data
These two perspectives are not interchangeable. Understanding this distinction helps reduce confusion about diagnosis and prevalence.
Each combination of BPD and co-occurring conditions creates a unique clinical picture. With 256 possible symptom combinations, no two people experience BPD in exactly the same way.
KEY TAKEAWAY
BPD rarely occurs in isolation. Co-occurring conditions are common and often reflect shared underlying processes, not entirely separate disorders. Understanding these overlaps supports more accurate diagnosis, more effective treatment planning, and more individualized care — and reinforces that improvement is possible.
Common Questions About Specific Conditions
ADHD
Research suggests that 10–27% of people with BPD also meet criteria for ADHD — not the other way around. ADHD is often the first diagnosis people receive because screening tools are widely available, medications may quickly improve some symptoms, and ADHD carries less stigma. As a result, ADHD may be identified before BPD, even when emotion dysregulation is the more central issue.
PTSD
A person can have PTSD, BPD, or both. Although there is ongoing debate about overlap, they are not the same condition, and treatment differs depending on which is primary. The focus here is not on resolving diagnostic debates, but on supporting effective responses regardless of labels.
Complex PTSD
Complex PTSD is a legitimate diagnosis, particularly for individuals without co-occurring BPD. However, people with BPD may appear to meet criteria for Complex PTSD, making the two difficult to clearly separate in practice.
Autism
Understanding of autism continues to evolve. At present, there are no reliable studies demonstrating a consistent link between autism and BPD. Emotion dysregulation can cause social difficulties, relationship challenges, and trouble reading cues, which may resemble autism and are also common during emotional distress.
Treatment Complexity and the “Peeling an Onion” Effect
BPD often exists alongside multiple diagnoses. For example, most people with BPD also experience depression, which is understandable given the intensity of emotional pain involved.
Treatment can feel like peeling an onion: as one layer improves, another may become more visible. Questions such as, “Which condition should be treated first?” or, “Which symptoms are primary?” are common and valid.
Sometimes co-occurring conditions are not addressed first because treating them alone may not significantly improve BPD. In many cases, treating BPD directly begins to improve other conditions as well. Medications can be helpful, and they typically target co-occurring conditions rather than the core features of BPD. Evidence-based therapies that focus on emotion regulation remain central.