What Is the Differential Diagnosis for Bipolar? A Deep Dive into a Complex Puzzle

I’ll never forget the first time I had a real conversation about bipolar disorder and misdiagnosis. It was over coffee with a close friend who had struggled with mood swings for years. She had been diagnosed with major depressive disorder at first, then later with borderline personality disorder, and finally, years later, with bipolar II disorder.

She sighed, stirring her coffee.
"I spent a decade on the wrong medications. How do doctors even figure this stuff out?"

That question stuck with me. How do mental health professionals differentiate between bipolar disorder and other psychiatric conditions? What makes bipolar disorder so tricky to diagnose, and what are the conditions that often mimic it?

Why Is Bipolar Disorder Often Misdiagnosed?

Bipolar disorder is one of the most misdiagnosed mental health conditions. A 2006 study found that 69% of people with bipolar disorder were misdiagnosed at least once, and one-third spent over 10 years with the wrong diagnosis before getting the right treatment.

But why? The symptoms of bipolar—mood swings, impulsivity, depression, energy changes—overlap with so many other conditions. A hypomanic episode might look like ADHD, while a severe depressive episode could be mistaken for major depression. Even medical conditions like thyroid disorders can cause similar symptoms.

So, let’s break down the most common differential diagnoses for bipolar disorder and why they sometimes get confused.

1. Major Depressive Disorder (MDD) – When Only One Side Is Seen

Many people with bipolar disorder first seek help during a depressive episode—because let’s be real, people are way more likely to go to a doctor when they feel horrible rather than when they feel "too good."

A psychiatrist once told me:
"If I only see a patient when they're depressed, it’s easy to misdiagnose them with major depressive disorder. But if I don’t ask the right questions about their past, I might miss the hypomanic or manic episodes."

Key difference:

• MDD involves persistent depressive episodes without manic or hypomanic episodes.
• In bipolar disorder, even if someone has mostly depressive episodes, there must be at least one episode of mania or hypomania to make the diagnosis.

How to tell them apart:

• Ask about past high-energy episodes—Did they ever feel euphoric, take impulsive risks, or have times when they barely needed sleep?
• Look at family history—Bipolar disorder has a strong genetic link.

2. Borderline Personality Disorder (BPD) – The Emotional Rollercoaster

This one is a big one. Bipolar disorder and BPD share some major symptoms:
Rapid mood swings
Impulsivity
Intense relationships
Emotional instability

I once had a friend who was diagnosed with BPD, only to later be rediagnosed with bipolar II disorder. She told me, "It felt like doctors were just flipping a coin between the two."

Key difference:

• Bipolar disorder moods last for days or weeks (e.g., a hypomanic episode might last 4-7 days).
• BPD mood swings can change within hours—someone might feel euphoric in the morning and devastated by the afternoon.
• Mania/hypomania in bipolar comes in episodes, whereas BPD is more of a persistent emotional dysregulation.

How to tell them apart:

• Ask about episode length—Do mood changes last for days or are they shifting hour by hour?
• Look at relationships—BPD often involves extreme fear of abandonment and unstable relationships.

3. Attention-Deficit/Hyperactivity Disorder (ADHD) – The Energy Dilemma

A friend with ADHD once joked, "I don’t know if I’m hyperactive or just having a manic episode." It’s a valid concern. Both conditions involve impulsivity, energy fluctuations, and difficulty focusing.

Key difference:

• ADHD is lifelong and often starts in childhood.
• Bipolar energy changes are episodic, meaning someone with bipolar can have weeks of high energy, followed by weeks of depression.
• Mania/hypomania includes mood elevation, whereas ADHD is more about consistent restlessness.

How to tell them apart:

• Look for cycles—ADHD is constant, whereas bipolar comes in waves of highs and lows.
• Check for grandiosity—People with mania often feel unstoppable or have inflated self-esteem, which isn’t common in ADHD.

4. Schizoaffective Disorder – When Mood Meets Psychosis

Schizoaffective disorder is like a blend of bipolar disorder and schizophrenia. It includes:
Mood episodes (mania or depression)
Psychotic symptoms (hallucinations or delusions)

Key difference:

• In bipolar disorder, psychotic symptoms happen only during mood episodes (e.g., delusions during mania).
• In schizoaffective disorder, psychotic symptoms occur even when mood symptoms are not present.

How to tell them apart:

• Track the psychotic symptoms—If they persist outside of manic or depressive episodes, schizoaffective disorder is more likely.

5. Thyroid Disorders – When It’s Not a Mental Health Issue

One of the wildest things I learned from a psychiatrist: A simple thyroid imbalance can mimic bipolar symptoms.

• Hyperthyroidism (overactive thyroid) → Can look like mania (high energy, racing thoughts).
• Hypothyroidism (underactive thyroid) → Can look like depression (fatigue, low motivation).

How to tell them apart:

• Do a blood test! It’s easy to check thyroid levels, and doctors often do this to rule out medical causes before diagnosing bipolar disorder.

Final Thoughts: Why This Matters

Back at that coffee shop, my friend looked up after hearing all of this and sighed.
"So basically, diagnosing bipolar disorder is like solving a giant mystery?"

Exactly. Mental health is complicated, and no diagnosis is made overnight. But understanding the differential diagnoses helps people get the right treatment faster.

So if you or someone you know has been given a diagnosis of bipolar disorder—or is questioning it—keep asking questions. The more we know, the better we can advocate for ourselves and others.

And sometimes, that starts with a simple conversation over coffee.

Is 165 cm normal for a 15 year old?

The predicted height for a female, based on your parents heights, is 155 to 165cm. Most 15 year old girls are nearly done growing. I was too. It's a very normal height for a girl.

Is 160 cm too tall for a 12 year old?

How Tall Should a 12 Year Old Be? We can only speak to national average heights here in North America, whereby, a 12 year old girl would be between 137 cm to 162 cm tall (4-1/2 to 5-1/3 feet). A 12 year old boy should be between 137 cm to 160 cm tall (4-1/2 to 5-1/4 feet).

How tall is a average 15 year old?

Average Height to Weight for Teenage Boys - 13 to 20 Years

How to get taller at 18?

Staying physically active is even more essential from childhood to grow and improve overall health. But taking it up even in adulthood can help you add a few inches to your height. Strength-building exercises, yoga, jumping rope, and biking all can help to increase your flexibility and grow a few inches taller.

Is 5.7 a good height for a 15 year old boy?

Generally speaking, the average height for 15 year olds girls is 62.9 inches (or 159.7 cm). On the other hand, teen boys at the age of 15 have a much higher average height, which is 67.0 inches (or 170.1 cm).

Can you grow between 16 and 18?

Most girls stop growing taller by age 14 or 15. However, after their early teenage growth spurt, boys continue gaining height at a gradual pace until around 18. Note that some kids will stop growing earlier and others may keep growing a year or two more.

Can you grow 1 cm after 17?

Even with a healthy diet, most people's height won't increase after age 18 to 20. The graph below shows the rate of growth from birth to age 20. As you can see, the growth lines fall to zero between ages 18 and 20 ( 7 , 8 ). The reason why your height stops increasing is your bones, specifically your growth plates.