We’re continuing today with the Comorbidity Series, a monthly series of posts about ADHD and comorbidity with other common psychiatric conditions. You can see all of the posts here.

Comorbidity is the occurrence of two or more psychiatric and/or neuropsychological conditions in a person. If a person has ADHD and anxiety, the conditions are considered comorbid.

Comorbidity can be tough! It makes diagnosis difficult, especially when those two or more conditions present with similar manifestations. Then it can be difficult to say “what’s the ADHD” and “what’s the other condition”.

Today we’re talking ADHD and Borderline Personality Disorder, which often occur together.

A very important note: I have not been diagnosed with Borderline Personality Disorder, so everything I’ve written here is not from personal experience but from research. If you feel any of the information is misleading or otherwise incorrect, I genuinely would ask you to reach out. I tried to keep this clinical and I wanted to be honest about not having a first-person perspective!

Defining Each Condition

Attention Deficit Hyperactivity Disorder (ADHD) is a neuropsychological disorder characterized by difficulty with paying attention, hyperactivity, impulsivity, and/or difficulty controlling or regulating emotions. ADHD is broken into three categories (or presentations): Primarily Inattentive, Primarily Hyperactive-Impulsive, and Combined.

Borderline Personality Disorder (BPD) is what may colloquially be called a “mood disorder” or “personality disorder”, a psychological condition in which a person may experience difficulty controlling or regulating emotions, impulsivity, unstable self-image, and difficulty maintaining interpersonal relationships.

Overlapping Manifestations

There are two key manifestations that have overlap between BPD and ADHD: impulsivity and emotional dysregulation.


Though it is a key manifestation for both conditions, the overlap of impulsivity occurs in the behavior, not in the motivation to act impulsively, because there are different types of impulsivity.

Those who have ADHD may find their impulsivity is cognitive/attentional impulsivity, which is difficulty suppressing unwanted or irrelevant thoughts, and/or difficulty weighing the consequences of an action. Or they may experience motor impulsivity, which is essentially acting without thinking, or non-planning impulsivity, acting without regard to the future.

Those who have BPD may find they experience more emotional impulsivity, wherein their impulsive actions are a response to a heightened emotional state.

A person with both ADHD and BPD may experience impulsive behavior due to a variety of factors. In making a comorbid diagnosis it would be crucial to understand the root cause of impulsivity for different scenarios.

Emotional Dysregulation

Emotional dysregulation refers to a person’s inability to effectively manage or control their emotions. People who experience emotional dysregulation may experience constant mood shifts (lability), outbursts of sudden emotion, or difficulty moving on from strong emotions.

Road rage is an example of emotional dysregulation. A person with road rage may become increasingly angry at other drivers on the road for their poor driving tactics. This person may feel the need to physically engage with other drivers to release the tension. They have no means for controlling their explosive anger, and thus turn to violence.

Emotional dysregulation is considered a core manifestation of BPD. People with BPD may experience heightened emotional sensitivity to real or perceived slights. They may have difficulty controlling anger, sadness, or fear, and can appear paranoid in their need for external validation. People with BPD may also have difficulty “coming down” from heavy emotions. They may linger in their anger, sadness or fear for longer than a person without BPD.

With ADHD, emotional dysregulation is considered a secondary manifestation. People with ADHD may experience emotional dysregulation because of the struggles they experience with their primary manifestations like impulsivity and difficulty sustaining attention. New research suggests that emotional dysregulation is genetically linked to ADHD, and should be considered a primary manifestation.


ADHD and BPD have much in common, but are two distinct conditions with as many differences.

Probable Causes

We are very sure that ADHD has an element of genetic predisposition, with a heritability rating of 70-80%. We are less sure currently if BPD is genetic, due to fewer research studies having been done, and heritability is estimated at 35-46%.

What is heritability? It’s a statistic that estimates the degree to which a trait is developed due to genetic factors.

BPD may arise from a combination of psychological and environmental factors – many researchers agree that early childhood trauma can influence its prevalence. BPD severity of manifestations fluctuates, and many people with BPD see a significant decline in many of their manifestations through adulthood with proper treatment (especially suicidal ideation, impulsivity and interpersonal difficulties). Manifestations don’t have to occur by a certain age to receive a diagnosis, and not everyone experiences manifestations before age 12.

ADHD is widely accepted as a neuropsychological condition, wherein the manifestations may be fairly consistent throughout a person’s life. Manifestations must have appeared before age 12 to receive a clinical diagnosis. Research is still seeking to answer the question of whether childhood trauma and/or negative experiences may impact an ADHD diagnosis.

Interpersonal Relationships and Self Image

Many people with BPD and/or ADHD also experience difficulty with interpersonal relationships and low self-esteem. However the reasons for these difficulties are unique to each condition.

With BPD, interpersonal problems are often a core manifestation. Those who have it may have experienced some or many unstable and intense relationships, and may be familiar with the Idealization and Devaluation Cycle.

As part of this cycle, a person may initially idealize a partner (in the context of any type of relationship). Then something occurs that goes against that view (ex: a fight, a criticism). The person experiencing the cycle enters a state of devaluation, where they can find nothing good or positive about their partner.

With ADHD, interpersonal problems are often a direct result of manifestations. Difficulty sustaining attention long enough to hold a conversation, difficulty with working memory to remember that one has made plans with a friend, or difficulty with time blindness, which means consistently being late for events.

Are ADHD and BPD Interconnected?

Comorbidity of ADHD and BPD occur at high rates – anywhere between 18% and 34% of adults with ADHD are estimated to also have BPD. But are they inherently interconnected?

Four theories have been put forward about why they have such a high correlation rate:

  1. ADHD may be considered a developmental forerunner of BPD. This means that ADHD occurring in childhood is an early sign of probable development of BPD in adulthood.
  2. ADHD and BPD may be different categories of one condition, rather than separate conditions.
  3. ADHD and BPD may share many of the same root causes, including brain structure.
  4. The presence of one condition may increase the risk of developing the other condition. This is in part due to their key overlapping manifestations.


Like with all comorbidities, treatment should focus on the most effective methods for each condition. Yet treatment for both conditions may be difficult for a number of reasons.

For ADHD, treatment may involve medication (stimulant or nonstimulant), coaching, support groups, and Cognitive Behavioral Therapy (CBT).

Those who have it may struggle with activation, planning, time blindness, and consistency. This means that remembering to take medication, the search for a therapist, and being on time to, or even remembering to attend, therapy sessions won’t come easy.

For BPD, psychotherapy is the most typical treatment option – specifically Dialectical Behavior Therapy (DBT) and Mentalization-Based Treatment (MBT). Medication can also be prescribed for assistance in emotional regulation.

Those who have it may struggle to maintain interpersonal relationships. This could mean developing a long-term relationship with a therapist won’t come easy.

You can see how having both conditions at once could make treatment a challenge, but it’s never impossible. Through the right combination of therapy, medication, coaching, and support groups, many with comorbid ADHD and BPD are able to manage their manifestations and live the kind of life they desire.

A Hopeful Future

The hope is that additional research will be done not just on the individual conditions, but on their comorbidity. This research may include common manifestations and possible inter-connectedness. Eventually we may come to fully understand the causes and most effective treatments for them together.

If you have ADHD and BPD, I’d love to hear about your experiences with diagnosis and treatment!


In no particular order or citation style:

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