The Difference Between Bipolar Disorder, Borderline Personality Disorder and Adult ADHD

It can be very challenging for even the most experienced clinician to distinguish the differences between Bipolar Disorder, Type II, Borderline Personality Disorder and Adult ADHD. Symptoms often overlap and these disorders frequently co-occur; however, there can be clues from the history and presentation that often help determine the diagnosis and the appropriate types of treatments. Below, is a case of a patient with a challenging diagnosis followed by tips on differentiating Bipolar Disorder, Type II, Borderline Personality Disorder, and Adult ADHD.


Anna* is a 46 year-old, married nurse with three children. She presented with persistent low-grade depression, anxiety, and irritability. She was on probation at work for poor performance. She also had a long-standing history of difficulty with friendships.

She complained of life-long depression with intermittent episodes of more severe symptoms. During the more extreme episodes, she overslept, felt more irritable and anxious. She reported chronic racing thoughts and difficulty concentrating.

She had a chaotic childhood. Her father was a successful, workaholic attorney who was also an alcoholic. There were frequent, explosive fights between her parents. Anna was the oldest of 3 children and at the age of 10, her parents divorced. She became ensnarled in their long, drawn-out divorce process. In pre-school and elementary school, she had been quite precocious, according to school reports. She listened well, followed instructions, and had many close friends.

However, as the fighting intensified at home around third and fourth grades her grades dropped and she began to exhibit behavioral problems at school.

The above case represents a challenging diagnosis. Below are tips to help determine the diagnosis and whether there is the possibility of more than one diagnosis.

Mood Swings

Mood swings in Bipolar Disorder, Type II last for one to four days and include the person feeling “hyper”, “on top of the world”, irritable, invincible, elated, or even depressed despite being in a hypomanic episode.

People with Borderline Personality Disorder also have mood swings but they have feelings of sadness, anger, rage, or depression that is more chronically present and triggered by criticism, disappointment or stress. Also, people with Borderline Personality Disorder rarely feel elation.

People with Adult ADHD also describe mood swings and difficulty with managing moods; however, the duration is usually brief and due to low frustration tolerance. Also, in Adult ADHD there are feelings of shame, irritability, frustration, and sadness secondary to difficulty with school, work and relationships.


Similarly, the symptoms of impulsivity are present in all the disorders but with different histories. Impulsivity may manifest as sexual promiscuity, excessive shopping binges, poor decision-making, automobile accidents or speeding tickets, and careless mistakes. With Bipolar Disorder, Type II, the impulsivity is present only during the periods of hypomania compared to Borderline Personality Disorder and Adult ADHD, when the impulsivity occurs chronically or due to an emotional trigger.


All three disorders present with difficulty concentrating or focusing. This creates challenges with completing tasks, jumping from task to task, and starting projects without completing them. These symptoms occur in Bipolar Disorder, Type II only during the hypomanic phase but can be chronic with the other two disorders.


In Borderline Personality Disorder, there is more frequently a history of feeling empty and lonely, chaotic relationships, self-injury, and an extreme fear of abandonment. There is often a history of significant physical or sexual abuse during childhood or severe emotional neglect.

In Bipolar Disorder, Type II, there is frequently a family history of depression or Bipolar Disorder, and the symptoms of depression start at an earlier age. Also, depression is the more frequent complaint than hypomania.

In Adult ADHD, the person has persistent challenges with sustained attention, focus, executive functioning, distractibility, time management, procrastination, and significant difficulty with organization.

These symptoms may appear in the other two disorders; however, in Adult ADHD, the symptoms must have existed since childhood. In addition, ADHD has the highest genetic component of all three disorders and is estimated to have a concordance rate ranging from 60-80%. Thus, eliciting a history of other family members with ADHD increases the likelihood that the person may be dealing with Adult ADHD.

All three disorders can manifest “racing thoughts”. In Adult ADHD, these thoughts are intermittently present and are exacerbated when there is greater stress or challenge in the environment.

With Bipolar Disorder, Type II, the symptom of racing thoughts occurs only during the hypomanic phase. The racing thoughts are often described as “crowded thoughts” and thinking of new and creative projects.

In Borderline Personality Disorder, the racing thoughts are usually precipitated by an emotionally laden experience such as a fight with or criticism from a friend or colleague.

Case Continued:

Upon further discussion with Anna, she denied having hypomanic episodes. However, she described feeling empty, lonely and having low self-esteem. Under severe stress, she would become acutely agitated, suicidal, have feelings of worthlessness, and be absent from work.

Over her life, she has gone to the psychiatric emergency room 6 times for suicidal thoughts, but has never made an attempt. She has also had a partial hospitalization. In addition, she has a long history of self-injuring behaviors including anorexia, cutting, and unprotected sex with casual contacts.

Anna has Borderline Personality Disorder as well as dysthymia. My recommendation was to start schema therapy twice a week as well as start on an MAOI and to start treatment in an intensive Dialectical Behavioral Treatment Program (CBT). Even though a MAOI is not FDA approved for Borderline Personality Disorder or dysthymia, there research shows its efficacy.

Two years later, Anna’s mood has stabilized and she feels much less anxious. In addition, she has been able to enjoy more pleasure in her personal life and career. She has currently been in a relationship for 14 months, and although the direction of the relationship is unclear, she feels more comfortable tolerating the unknown.

This case presents the diagnostic challenges distinguishing Bipolar Disorder, Type II, Borderline Personality Disorder, and Adult ADHD. Using the above distinguishing features and taking a thorough assessment improves the accuracy of the diagnosis and helps in the determination of an effective treatment plan.


Hirschfeld RM,Cass AR, Hot DC, Carlson CA. Screening for bipolar disorder in patients treated for depression in a family medicine clinic. J Am Board Family Practice. 2005:18: 233-239

McIntyre, Roger. Differential Diagnosis of Bipolar Disorder. Supplement to Current Psychiatry. Bipolar Disorder. 2011: 3-22.

* To Maintain confidentiality