ADHD or Borderline Personality Disorder?

Written by the practice's editorial team. Published November 4, 2026; updated November 4, 2026. Part of the Adult ADHD Symptoms Guide, is it adhd? section. Editorial policy

Key points

NIMH lists self-harm, recurring suicidal thoughts or behaviors, chronic emptiness, unstable relationships and an unstable self-image among BPD symptoms.
In 118 women seeking BPD treatment, 41.5% had childhood ADHD and 16.1% had adult ADHD (Philipsen, 2008).
A 2026 meta-analysis estimated BPD in 21.9% of adults with ADHD, with very high variation between studies.
In a Swedish register study of more than 2 million people, an ADHD diagnosis carried an adjusted odds ratio of 19.4 for a BPD diagnosis.
NIMH calls psychotherapy the primary treatment for BPD and says medication is not first-line.

If you act before thinking, your moods shift quickly and relationships have been hard, you may have read about both ADHD and borderline personality disorder (BPD) and wondered which fits. The two share real features, they often occur together, and they are sometimes confused. This page compares them, gives co-occurrence rates from published studies, and explains why the distinction changes treatment.

If you are thinking about suicide or harming yourself, call or text 988, the Suicide and Crisis Lifeline, or chat at 988lifeline.org. In a life-threatening emergency, call 911. The National Institute of Mental Health (NIMH) says people with BPD have a significantly higher rate of self-harm and suicidal thoughts and behavior than the general population, and that anyone thinking of harming themselves needs help right away.

Where the two overlap

A 2021 review by Ditrich and colleagues describes overlap particularly in impulsivity and emotional dysregulation. Both conditions can bring acting on impulse, quick anger, trouble in relationships and substance problems. Adverse childhood events have been linked to both.

Emotional swings are not a reliable way to tell them apart. In a 2021 daily-life study of 98 women, Moukhtarian and colleagues measured feelings in the moment across ADHD, BPD, both conditions and healthy controls. The clinical groups differed from controls, but ADHD and BPD showed similar intensity of anger and irritability and similar instability of sadness, irritability and anger. The authors concluded that the presence or severity of emotional dysregulation should not be used in clinical practice to distinguish the two. The guide's page on emotional dysregulation in adult ADHD covers this further.

Side by side

Feature	ADHD	Borderline personality disorder
Timing	Symptoms starting before age 12	Usually diagnosed in late adolescence or early adulthood
Core problem	Inattention, hyperactivity and impulsivity	Difficulty regulating emotions, with impulsivity, an unstable sense of self and troubled relationships
Impulsivity	More motor impulsivity: trouble stopping an action already under way	Stress-dependent; more trouble using context cues to hold back a response
Relationships	Can be strained by forgetfulness, interrupting or impulsive choices	A pattern of intense, unstable relationships; efforts to avoid real or perceived abandonment
Sense of self	Not a defining feature	A distorted and unstable self-image
Inner state	Restlessness	Chronic emptiness; sometimes dissociation
Self-harm and suicidal behavior	Not a diagnostic criterion	Listed among the symptoms
Primary treatment	Medication, usually stimulants, and psychotherapy	Psychotherapy, such as dialectical behavior therapy (DBT)

The table draws on NIMH's publications on both conditions and the Ditrich review. The differences are tendencies seen across groups, and they cannot sort one person from a list. A single difficult relationship or a rejection that hurts badly does not point to either condition. The guide's page on rejection sensitivity explains what is and is not known about that experience, which is not a diagnosis.

How often they occur together

Rates vary a lot, largely because of who was studied and how.

Study	Sample	Finding
Philipsen et al., 2008	118 women seeking BPD treatment	41.5% had childhood ADHD; 16.1% had adult ADHD
Ferrer et al., 2010	Adult patients meeting BPD criteria	69 patients (38.1%) had adult ADHD
Adamis et al., 2026	Meta-analysis of 11 studies, 2,120 adults with ADHD	21.9% co-occurrence with BPD
Kuja-Halkola et al., 2021	2,113,902 people in Swedish registers	An ADHD diagnosis carried an adjusted odds ratio of 19.4 for a BPD diagnosis

The 2026 meta-analysis cautions that its estimates depend heavily on setting and instruments, with especially high rates in ADHD-specific clinics, and it warns about "diagnostic noise" from overlapping symptoms. The Swedish study also found raised risk in relatives, including full siblings, and its authors say the pattern suggests shared genetic factors.

Ferrer's group noticed two different profiles among people with BPD. Those who also had ADHD had more substance use disorders and a more impulsive profile, while those without ADHD had more mood and panic disorders.

The role of childhood trauma

Trauma matters to both pictures, and its timing can confuse the history. A 2020 review by Calvo and colleagues found only 4 relevant studies, all looking back on childhood. Three described increased risk of adult BPD among children with ADHD who reported emotional and sexual traumatic experiences. The authors say longitudinal studies are needed before calling these risk factors. Philipsen's team linked more severe adult BPD symptoms with childhood emotional abuse. The page on ADHD or trauma and PTSD goes deeper.

Why the answer changes treatment

Psychotherapy comes first for BPD. NIMH calls psychotherapy the primary treatment, and notes that DBT was developed specifically for people with BPD. Evidence-based treatments have been shown to help many people have fewer and less severe symptoms.
Medication plays a different role. NIMH says the benefits of medication for BPD are unclear and it is not first-line. The NICE guideline on BPD says drug treatment should not be used specifically for the disorder or its individual symptoms, though it may be considered for co-occurring conditions.
ADHD medication targets ADHD. NIMH lists medication, usually stimulants, and psychotherapy among the most common adult ADHD treatments. A 2026 network meta-analysis found only low-certainty evidence for methylphenidate in unselected BPD samples, and said prescribing should be limited to specific indications, such as co-occurring ADHD, after cautious appraisal.
Evidence for treating both together is thin. The Ditrich review says few studies have looked at treatment for the combined condition. One naturalistic study it describes found that people with both who took methylphenidate during DBT did better on anger, motor impulsiveness, depression and ADHD severity than those without a stimulant. In a 2026 uncontrolled study, 24 of 36 adults with both conditions completed follow-up on methylphenidate, and BPD criteria counts fell. The authors say causal conclusions cannot be drawn.
Safety comes first. NIMH says anyone thinking of harming themselves needs help right away. NICE's self-harm guideline includes developing a safety plan written with and agreed by the person.

Before starting treatment for a co-occurring condition, NICE advises reviewing both diagnoses, especially if either one was made during a crisis. That is worth remembering if a label came from an emergency visit.

Questions worth thinking through

Did teachers or family describe inattention or restlessness in early grade school, before the difficulties in relationships began?
Do attention problems continue when life and relationships are calm, or do they mainly appear under emotional stress?
Do you feel persistently empty, or unsure who you are from one week to the next?
Have you hurt yourself on purpose, or had thoughts of suicide?

These questions are prompts for a conversation and cannot give you a diagnosis. Bring your answers to any visit. If you are having thoughts of suicide or self-harm now, call or text 988 instead of waiting. The guide on preparing for an adult ADHD evaluation covers what else helps.

What Dr. Shershow's service does and does not cover

Dr. Shershow's practice focuses on adult ADHD. An evaluation considers other possible explanations and conditions alongside ADHD, and it ends with what was found and the treatment options that fit. Dr. Shershow's listed services are adult ADHD evaluation, treatment planning, medication management when appropriate and follow-up. BPD treatment is not among them. People with BPD should receive treatment from a licensed mental health professional, as NIMH advises, and DBT and similar therapies are delivered by clinicians trained in them. If an evaluation raises this question, the next step is to seek that care. Please do not wait for an evaluation appointment if you are in crisis: call or text 988.

Dr. Shershow evaluates and treats adults with ADHD located in New York or New Jersey. You can read more about the adult ADHD evaluation.

Questions

Can you have ADHD and borderline personality disorder at the same time?

Yes. In 118 women seeking BPD treatment, 16.1% had adult ADHD, and a 2026 meta-analysis estimated BPD in 21.9% of adults with ADHD. Rates vary widely by setting and method.

Is BPD often misdiagnosed as ADHD, or the other way round?

Overlap makes confusion possible, but how often it happens is not established. A 2026 review says prospective studies do not establish how often adult ADHD is diagnosed instead of BPD. Careful history taking is the way to sort it out.

How can a clinician tell them apart if emotions swing in both?

Not by emotional swings alone: a 2021 daily-life study found similar intensity and instability in both. Clinicians look at childhood onset of inattention or hyperactivity, and at features of BPD such as unstable self-image, fear of abandonment, emptiness and self-harm.

Do stimulants help BPD?

Evidence does not support stimulants as a treatment for BPD itself. A 2026 network meta-analysis found only low-certainty evidence for methylphenidate in unselected BPD samples. Studies in people with both conditions are small and uncontrolled, so results are preliminary.

What should I do if I have thoughts of self-harm?

Call or text 988 or chat at 988lifeline.org right away. In a life-threatening emergency, call 911. You do not need a diagnosis to get help.

Sources

This article is general information, not medical or legal advice. Rules and coverage change; check the linked sources for the current position, and speak with a clinician or attorney about your own situation.

ADHD or borderline personality disorder?