How to Differentiate Between Bipolar Disorder and ADHD

Because there are similarities in the symptoms of bipolar disorder and attention-deficit/hyperactivity disorder (ADHD), differentiating between the 2 psychiatric conditions can be challenging for clinicians.

To help ensure accurate diagnoses, researchers from the Icahn School of Medicine at Mount Sinai in New York City aimed to identify where ADHD and bipolar disorder in adult patients overlap and diverge symptomatically and epidemiologically. The authors based their criteria on the clinical diagnoses of the disorders described in the latest Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and published their findings in the Journal of Psychiatric Practice.

According to the researchers, the DSM-5 classifies adult ADHD symptoms into 2 clusters: inattention and hyperactivity/impulsivity. In order to diagnose an adult patient with ADHD, at least 5 of either 9 inattention symptoms or 9 hyperactivity/impulsivity symptoms must have been present over the past 6 months.

In contrast, bipolar disorder is characterized by at least 1 manic or hypomanic episode within a patient’s lifetime. The DSM-5 diagnostic criteria for a manic or hypomanic episode include a “distinct period of abnormally and persistently elevated, expansive, or irritable mood” and “persistently increased goal-directed activity or energy” that lasts at least 1 week or requires hospitalization (manic episode), or lasts at least 4 days (hypomanic episode).

Nevertheless, a number of diagnostic criteria for the 2 disorders are similar. In fact, several symptoms from the 2 ADHD clusters appear to overlap with the characteristics of bipolar disorder, which include acting as if “driven by a motor,” being easily distracted, and talking excessively.

Despite that overlap, the authors identified 5 areas where the bipolar disorder and ADHD vary significantly:

• Age of onset: ADHD symptoms typically appear by age 7, while bipolar symptoms are rare in adolescents and generally present between young and middle adulthood.
• Epidemiology: Adult ADHD is at least twice as prevalent as bipolar disorder in the general population.
• Disease course: ADHD is defined as a noncyclical, chronic disorder, while bipolar disorder is characterized by episodes of depression, mania, or hypomania intermingled with periods of normal mood and energy.
• Mood: ADHD itself does not feature a sustained change in mood, though patients with ADHD can have comorbid mood disorders.
• Psychosis and extreme symptomatology: Unlike bipolar patients, ADHD patients who express restlessness, talkativeness, and risky behavior do not usually increase productivity, lose verbal coherence, or end up in the emergency room because of those symptoms.

“Although the existence of phenomenological overlap, the high prevalence of depressive episodes in patients with ADHD and the existence of true ADHD-bipolar disorder comorbidity can make this differential diagnosis difficult, some clear characteristics distinguish the 2 disorders,” the authors concluded. “…Clinicians can work to differentiate these disorders by paying careful attention to phenomenology and by taking a thorough history when patients present in their offices.”

Noting that it is also important for clinicians to understand that the 2 conditions may occur simultaneously, the researchers cited a previous study that found that 21% of adult patients with bipolar disorder had comorbid ADHD, as well as another study that calculated a lifetime ADHD prevalence of 9.5% in the first 1000 bipolar disorder patients it examined.