March 17, 2008 (Savannah, Georgia) — A study of consecutive patients seen in an anxiety-disorders clinic found that 33% met criteria for adult attention-deficit/hyperactivity disorder (ADHD), which is much higher than the 4.4% prevalence of adult ADHD in the US population.
These findings, by Michael Van Ameringen, MD, and colleagues from McMaster University Medical Center, in Hamilton, Ontario, were presented in a talk here at the Anxiety Disorders Association of America 28th Annual Meeting.
"When we looked at individuals who were walking in for treatment for their anxiety disorder, we found that 33% of them met criteria for ADHD in adults, and they were not seeking treatment for this," Dr. Van Ameringen told Medscape Psychiatry.
It is important to be aware that adult ADHD exists and that probably about 50% of children do not grow out of it, he added. Often it is often not picked up because it co-occurs with other psychiatric illness. Even though adult ADHD is not specified in the Diagnostic and Statistical Manual of Mental Disorders, 4th ed (DSM-IV), the US Food and Drug Administration (FDA) has given approval for the use of new long-acting stimulants for ADHD in children, adolescents, and adults, he noted.
ADHD is the most common psychiatric disorder of childhood, and it accounts for up to 50% of clinical cases in childhood psychiatry, he told the audience. The prevalence of childhood ADHD is reported to be 3% to 10%, and it is highly comorbid with conduct disorder, oppositional-defiance disorder, anxiety disorder, and bipolar disorder.
There are no specific criteria for adult ADHD in the DSM-IV, so clinicians must apply the criteria for childhood ADHD (such as onset before age 7 years), although this is expected to change with the DSM-V, he said.
Although childhood ADHD often resolves, 36% to 55% of children maintain symptoms in adulthood.
Symptoms of ADHD take on different forms in adults:
Symptoms of hyperactivity in children with ADHD (squirming, fidgeting, inability to stay seated, running and climbing excessively, inability to play and work quietly, talking excessively) translate into different symptoms in adults (workaholic tendencies, being overscheduled and overwhelmed, self-selecting very active jobs, constantly active, talking excessively).
Similarly, symptoms of impulsivity in children (blurting out answers, not waiting his or her turn, intruding on or interrupting others) manifest differently in adults (low frustration tolerance, short temper, quitting jobs abruptly, ending relationships, driving too fast, addictive" personality).
Finally, symptoms of inattention differ in children with ADHD (difficulty in sustaining attention, not listening, not following through, inability to organize, losing important items, easily distractible, forgetful) vs adults with ADHD (showing incredible procrastination, slow, inefficient, very poor time-management skills, very disorganized)
Childhood ADHD is more common in boys, with a male:female prevalence ratio of 10:1 in clinical samples and 3:1 in community samples, he added, noting that, in adults, this ratio is closer to 3:2.
Most cases of childhood ADHD are the combined (inattentive and impulsive/hyperactive) type, but more cases of adult ADHD are the inattentive type. It is interesting to note that ADHD might not be detected in girls because they have the inattentive subtype, he said.
ADHD is a highly heritable condition, with a heritability factor of 0.76, which is greater than that for breast cancer, asthma, or schizophrenia.
"One of the surprising findings from the National Comorbidity Survey-Replication [NCS-R] study, for many people, was that the prevalence of adult ADHD meeting strict DSM-IV criteria was 4.4%, which makes adult ADHD 1 of the most common conditions in adulthood," said Dr. Van Ameringen.
The survey found a 5:3 male:female prevalence of adult ADHD, and individuals with adult ADHD were more likely to also have anxiety disorders, mood disorders, and social phobia (Kessler RC et al. Am J Psychiatry. 2006;163:716-23). Only 25% of the individuals found to have adult ADHD had ever had treatment for ADHD, and only 10% had treatment in the past month.
Prevalence of ADHD with Anxiety
Dr. Van Ameringen and colleagues aimed to determine the prevalence of childhood and adult ADHD in a sample of patients seen in an anxiety-disorders clinic. They looked at 97 consecutive patients referred to their clinic. The patients completed an Adult ADHD Self-Report Scale version 1.1 symptom checklist and were also assessed with a structured clinical interview for DSM-IV, which included the ADHD module of the Mini International Neuropsychiatric Interview (MINI).
They found that 32 of the 97 adults (33%) met the MINI criteria for adult ADHD, and similarly, 29 of the 88 adults (33%) who completed the self-report checklist met criteria for adult ADHD.
Only 9 of the 32 individuals (28%) who met the criteria for adult ADHD had previously been identified as having ADHD; only 7 of these 9 individuals (22%) had ever been treated for this disorder, and only 1 person was currently receiving treatment for this.
Most individuals identified as having adult ADHD "know they've had these symptoms, but no one has made the formal diagnosis," said Dr. Van Ameringen.
It is hoped that the DSM V will have better criteria to diagnose this condition, he added.