An irritable, inattentive, and disruptive child: Is it ADHD or bipolar disorder?
Clinical characteristics, rating scales, nomograms help guide diagnosis
The next strategy is to look at Bill’s scores on externalizing behaviors using an instrument such as the Vanderbilt ADHD Diagnostic Parent Rating Scale. Few pediatric patients with BD will score low on externalizing behaviors.14 Bill scores in the clinically significant range for hyperactivity/impulsivity and positive on the screeners for ODD, conduct disorder (CD), and anxiety/depression.
You decide that Bill is at high risk of pediatric BD; he has a post-test probability of approximately 45%, and many externalizing behaviors on the Vanderbilt. You give Bill a diagnosis of BD I and ADHD and prescribe risperidone, 0.5 mg/d, which results in significant improvement in mood swings and other manic behaviors.
ADHD
Epidemiology. ADHD is one of the most common neurodevelopmental disorders in childhood, with prevalence estimates of 8% of U.S. children.15,16 Overall, boys are more likely to be assigned a diagnosis of ADHD than girls.15 Although ADHD often is diagnosed in early childhood, research is working to clarify the lifetime prevalence of ADHD into late adolescence and adulthood. Current estimates suggest that ADHD persists into adulthood in close to two-thirds of patients.17 However, the symptom presentation can change during adolescence and adulthood, with less overt hyperactivity and symptoms of impulsivity transitioning to risky behaviors involving trouble with the law, substance use, and sexual promiscuity.17
As in pediatric BD, comorbidity is common in ADHD, with uncomplicated ADHD being the exception rather than the rule. Recent studies have suggested that approximately two-thirds of children who have a diagnosis of ADHD have ≥1 comorbid diagnoses.15 Common comorbidities are similar to those seen in BD, including ODD, CD, anxiety disorders, depression, and learning disability. Several tools and resources are available to help clinicians navigate these issues within their practices.
Family history. Genetics appear to play a large role in ADHD, with twin studies suggesting inheritance of approximately 76%.18 Environmental factors contribute, either in the development of ADHD or in the exacerbation of an underlying familial predisposition. Interestingly, in children with BD, family history often is significant for several family members who have both ADHD and BD. However, in children with ADHD only, family history often reflects an absence of family members with BD.19 Although not diagnostic, this pattern can be helpful when considering a diagnosis of BD vs ADHD.
Clinical picture. ADHD often is recognized in childhood; DSM-5 criteria specify that symptoms be present before age 12 and persist for at least 6 months. This characterization of the timing of symptoms helps exclude behavioral disruptions related to external factors such as trauma (eg, death of a caregiver) or abuse. It also is important to note that symptoms might be present earlier but not come to attention clinically until a later age, perhaps because of increasing demands placed on the child by school, peer groups, and extracurricular activities. To make an ADHD diagnosis, symptoms must be present in >1 setting and interfere with functioning or development.
Core symptoms of ADHD include inattention, hyperactivity, and impulsivity that are out of proportion to the child’s developmental level (Table 2).20 When considering diagnosis of ADHD, 6 of 9 symptoms for inattention and/or hyperactivity-impulsivity must be present at a clinically significant level.
Three different ADHD presentations are recognized: combined, inattentive, and hyperactive impulsive. Children with predominant impulsive and hyperactive behaviors generally come to clinical attention at a younger age; inattentive symptoms often take longer to identify.
Children with ADHD have been noted to have lower tolerance for frustration, which might make anger outbursts and aggressive behavior more likely. Anger and aggression in ADHD often stem from impulsivity, rather than irritable mood seen with BD.18 Issues related to self-esteem, depression, substance use, and CD can contribute to symptoms of irritability, anger, and aggression that can occur in children with ADHD. Although these symptoms can overlap with those seen in children with BD, other core symptoms of ADHD will not be present.
ODD is one of the most common comorbidities among children with ADHD, and the combination of ODD and ADHD may be confused with BD. Children with ODD often are noted to exhibit a pattern of negative and defiant behavior that is out of proportion to what is seen in their peers and for their age and developmental level (Table 3).20 When considering an ODD diagnosis, 4 out of 8 symptoms must be present at a clinically significant level.
The following case highlights the potential similarities between ADHD/ODD and BD, with tips on how to distinguish them.
CASE REPORT
Angry and destructiveSam, age 7, has been given a diagnosis of ADHD, but his parents think that he isn’t improving with methylphenidate treatment. They are concerned that he has anger issues like his uncle, who has “bipolar disorder.”
