An irritable, inattentive, and disruptive child: Is it ADHD or bipolar disorder?

Differentiating the irritable, oppositional child with attention-deficit/hyperactivity disorder (ADHD) from the child with bipolar disorder (BD) often is difficult. To make matters more complicated, 50% to 70% of patients with BD have comorbid ADHD.^1,2 Accordingly, clinicians are often faced with the moody, irritable, dis­ruptive child whose parents want to know if he (she) is “bipolar” to try to deal with oppositional and mood behaviors.

In this article, we present an approach that will help you distinguish these 2 disorders from each other.

Precision medicineThere is a lack of evidence-based methods for diagnosing psychiat­ric disorders in children and adolescents. DSM-5 provides clinicians with diagnostic checklists that rely on the clinician’s judgment and training in evaluating a patient.³ In The innovator’s prescription: a dis­ruptive solution for health care, Christensen et al⁴ describe how medi­cine is moving from “intuitive medicine” to empirical medicine and toward “precision medicine.” Intuitive medicine depends on the clini­cian’s expertise, training, and exposure to different disorders, which is the traditional clinical model that predominates in child psychiatry. Empirical medicine relies on laboratory results, scans, scales, and other standardized tools.

Precision medicine occurs when a disorder can be precisely diag­nosed and its cause understood, and when it can be treated with effec­tive, evidence-based therapies. An example of this movement toward precision is Timothy syndrome (TS), a rare autosomal dominant disorder characterized by physical malformations, cardiac arrhyth­mias and structural heart defects, webbing of fingers and toes, and autism spectrum disorder. In the past, a child with TS would have been given a diagnosis of intellectual disability, or a specialist in developmental disorders might recognize the pattern of TS. It is now known that TS is caused by muta­tions in CACNA1C, the gene encoding the calcium channel Ca_v1.2α subunit, allowing precise diagnosis by genotyping.⁵

Although there are several tools that help clinicians assess symptoms of ADHD and BD, including rating scales such the Vanderbilt ADHD Diagnostic Rating Scale and Young Mania Rating Scale, none of these scales are diagnostic. Youngstrom et al^6,7 have developed an evidence-based strategy to diagnose pediatric BD. This method uses a nomogram that takes into account the base rate of BD in a clinical set­ting and family history of BD.

We will describe and contrast the epi­demiologic and clinical characteristics of pediatric BD from ADHD and use the Youngstrom nomogram to better define these patients. Although still far from pre­cision medicine, the type of approach rep­resents an ongoing effort in mental health care to increase diagnostic accuracy and improve treatment outcomes.

Pediatric bipolar disorder
Prevalence of pediatric BD is 1.8% (95% CI, 1.1% to 3.0%),⁸ which does not include sub-threshold cases of BD. ADHD and oppo­sitional defiant disorder (ODD) are 8 to 10 times more prevalent. For the purposes of the nomogram, the “base rate” is the rate at which a disorder occurs in different clinical settings. In general outpatient clinics, BD might occur 6% to 8% of the time, whereas in a county-run child psychiatry inpatient facility the rate is 11%.⁶ A reasonable rate in an outpatient pediatric setting is 6%.

Family history. In the Bipolar Offspring Study,9 the rate of BD in children of par­ents with BD was 13 times greater than that of controls, and the rate of anxiety and behavior disorders was approximately twice that of children of parents without BD (Table 1).⁹ This study evaluated 388 children of 233 parents with BD and 251 children of 143 demographically matched controls.

Clinical characteristics. Children and adolescents with BD typically manifest with what can be described as a “mood cycle”—a pronounced shift in mood and energy from one extreme to another. An example would be a child who wakes up with extreme silliness, high energy, and intrusive behavior that persists for several hours, then later becomes sad, depressed, and suicidal with no precipitant for either mood cycle.¹⁰ Pediatric patients with BD also exhibit other symptoms of mania dur­ing mood cycling periods.

Elevated or expansive mood. The child might have a mood that is inappropriately giddy, silly, elated, or euphoric. Often this mood will be present without reason and last for several hours. It may be distin­guished from a transient cheerful mood by the intensity and duration of the episode. The child with BD may have little to no insight about the inappropriate nature of their elevated mood, when present.

Irritable mood. The child might become markedly belligerent or irritated with intense outbursts of anger, 2 to 3 times a day for several hours. An adolescent might appear extremely oppositional, belliger­ent, or hostile with parents and others.