At what age does bipolar disorder usually appear?

NIMH says most people are diagnosed in adolescence or adulthood, but symptoms can appear earlier in childhood. ADHD is different: its symptoms must begin before age 12. A teenager whose problems started suddenly in the teen years needs a careful look at mood.

Is there a blood test or brain scan for bipolar disorder or ADHD?

No. NIMH says no blood test or brain scan can diagnose bipolar disorder, and MedlinePlus says no test can diagnose ADHD. Both diagnoses come from a detailed history, interviews, and observation over time.

Does a stimulant that causes mania-like symptoms prove my teenager has bipolar disorder?

No. The Concerta label says stimulants can cause psychotic or manic symptoms in patients with no history of mania, in about 0.1% of patients in pooled short-term trials. Call the prescriber right away if this happens. The prescriber will decide what the reaction means.

Can a child who had DMDD get a bipolar diagnosis later?

DMDD and bipolar disorder are separate diagnoses. DMDD describes constant irritability and outbursts, and bipolar disorder needs distinct mood episodes. If clear episodes of mania or depression appear later, a clinician will evaluate the teenager again.

What is the usual treatment for bipolar disorder in a teenager?

AACAP says treatment usually includes education for the teenager and family, mood-stabilizing medication such as lithium or an atypical antipsychotic, and psychotherapy. A child and adolescent psychiatrist makes the plan. If ADHD is also present, the prescriber decides how and when to treat it.

How Do You Tell If a Teenager Has Bipolar Disorder or ADHD?

The short answer: No single test separates the two. Clinicians look at the pattern over time. ADHD symptoms start before age 12 and stay fairly constant. Bipolar disorder comes in episodes: clear changes in mood, energy, and sleep that last days or weeks. Some teenagers have both conditions, so the answer is not always one or the other.

Why do bipolar disorder and ADHD look alike in teenagers?

Several symptoms are on both lists. The American Academy of Child and Adolescent Psychiatry (AACAP) lists these signs of a manic episode in its family guide to bipolar disorder in children and teens: talking too much and too fast, distractibility, and repeated high-risk behavior. The National Institute of Mental Health (NIMH) describes ADHD with very similar words on its ADHD page: trouble paying attention, talking excessively, restlessness, and interrupting.

So distractibility, fast talk, high activity, and impulsive acts can point to either condition.

NIMH says this plainly. Its page on bipolar disorder in children and teens names ADHD as one of the disorders with symptoms like those of bipolar disorder. A 2016 review in the Journal of Clinical Psychiatry adds a second problem. Children often do not show the full criteria for a mood episode, and that makes the diagnosis harder.

What separates bipolar disorder from ADHD?

A 2015 review in Current Psychiatry Reports says clinicians separate the two by clinical features, family history, course of illness, and response to treatment. These are the features that carry the most weight.

Course: constant or in episodes. This is the main one. NIMH says ADHD behaviors are frequent and occur across many situations. Bipolar disorder is "often episodic." Mood episodes last several days or weeks, and they are a change from how the teenager usually is.
Age at the start. NIMH says ADHD symptoms must begin before age 12. Most people with bipolar disorder are diagnosed in adolescence or adulthood, although symptoms can appear earlier.
Need for sleep. AACAP describes a manic teenager who can go with little or no sleep for days and not feel tired. The NIMH list of ADHD symptoms does not include a lower need for sleep.
Grandiosity. NIMH lists "an inflated sense of ability, knowledge, and power" as a sign of mania. AACAP calls it unrealistic highs in self-esteem. This is not on the ADHD symptom list.
Elevated mood. Intense happiness or silliness for long periods points to mania. So does thinking that feels like it is on fast forward.
Depressive episodes. Periods of sadness, low energy, hopelessness, or thoughts of death are part of bipolar disorder. They are not ADHD symptoms.
Family history. A parent with bipolar disorder raises the chance. A 2018 meta-analysis of 17 studies found that these children were nine times more likely to have a bipolar-type disorder than children of parents without psychiatric illness. They also had a higher risk of ADHD, so family history alone does not settle the question.

For a closer look at the mania list, see the signs of mania. For the genetics, see is bipolar disorder hereditary.

Can a teenager have both bipolar disorder and ADHD?

Yes, and it is common in young people with bipolar disorder. A 2015 systematic review of 167 studies looked at children and adolescents with bipolar disorder. The weighted mean rate of ADHD in that group was 48%. Only anxiety disorders were more common, at 54%.

The link looks weaker from the other direction, and the best numbers are from adults. A 2021 meta-analysis of 71 studies found that about 1 in 13 adults with ADHD (7.95%) also had a bipolar diagnosis. Nearly 1 in 6 adults with bipolar disorder (17.11%) had ADHD. Rates varied widely between studies. Bipolar disorder also started about 4 years earlier in people who had ADHD too.

So most people with ADHD do not have bipolar disorder. But an ADHD diagnosis does not rule it out if clear mood episodes appear later.

Could it be DMDD and not bipolar disorder or ADHD?

It could, mainly in a younger child. Disruptive mood dysregulation disorder (DMDD) describes ongoing irritability with severe temper outbursts. NIMH lists the main features on its DMDD page:

Severe temper outbursts, on average 3 or more times per week
An irritable or angry mood most of the day, nearly every day
Symptoms that have continued for 12 or more months
Trouble in more than one place, such as home, school, or with peers

NIMH says youth with DMDD are diagnosed between the ages of 6 and 10. So a teenager does not usually get this diagnosis for the first time, but may have received it years earlier.

DMDD exists because of the bipolar question. A 2014 article in the American Journal of Psychiatry explains that many children with constant irritability had received a bipolar diagnosis without distinct mood episodes. The difference is again the course. DMDD irritability is constant. Bipolar mood changes come in episodes.

How do clinicians evaluate a teenager?

They take a history, and they take time. NIMH says no blood test or brain scan can diagnose bipolar disorder. AACAP says the diagnosis "is complex and involves careful observation over an extended period of time." It recommends a full evaluation by a child and adolescent psychiatrist or a trained mental health professional.

The 2016 review describes three parts of the work:

Interview the parents and the teenager about behavior.
Review the family history in detail.
Rule out other disorders one at a time.

For ADHD, NIMH says the clinician looks for symptoms that have lasted at least 6 months and appear in two or more settings. It says providers may gather input from people who know the teenager well and use rating scales.

You can help by keeping a dated record. Write down sleep hours, mood, energy, and any behavior that is unlike your teenager. Sleep is a useful clue, and insomnia.md covers ordinary teenage sleep problems. A record over several weeks shows whether the symptoms are constant or come in episodes. The diagnosis can take a long time, as how long it takes to get a bipolar diagnosis explains.

Are ADHD stimulants safe if a teenager has bipolar disorder?

The evidence is mixed, and the best studies are in adults. This is a decision for the prescriber.

The FDA label for Concerta (methylphenidate) says stimulants "may induce a manic or mixed episode in patients with bipolar disorder." It tells prescribers to screen first for risk factors, such as a history of depressive symptoms or a family history of suicide, bipolar disorder, or depression. In pooled short-term trials, psychotic or manic symptoms occurred in about 0.1% of stimulant-treated patients without that history, compared with 0% on placebo.

Two registry studies of adults with bipolar disorder give more detail:

A Swedish study of 2,307 adults found a higher rate of mania in the 3 months after methylphenidate was started without a mood stabilizer (hazard ratio 6.7). In patients who took a mood stabilizer, the rate of mania was lower after the start (hazard ratio 0.6).
A Danish study of 1,043 patients found no increase in mania after methylphenidate. Manic episodes fell by 48%, but the authors attributed that to regression to the mean and not to the drug.

Evidence in young people is thinner. A 2024 systematic review found 11 pediatric studies. Some reported that stimulants were safe and well tolerated in children with both conditions. Others reported treatment-emergent mania and discontinuation. The 2015 systematic review found that randomized trials showed a better response to stimulants than to placebo when they were added for ADHD symptoms in bipolar youth.

Tell the prescriber about any family history of bipolar disorder before a stimulant is started. Report new sleeplessness without tiredness, unusual elation, or racing speech right away.

The bottom line

ADHD is a constant pattern that starts before age 12. Bipolar disorder comes in episodes, with a lower need for sleep, grandiosity, and periods of depression. About half of young people with bipolar disorder also have ADHD, so both diagnoses are possible. If your teenager talks about death or suicide, call or text 988 now.

Last updated: October 2026. This article is for informational purposes only and does not constitute medical advice. Only a qualified clinician who has evaluated your teenager can diagnose bipolar disorder, ADHD, or DMDD, and no medication should be started or stopped without the prescriber.