David W. Goodman, M.D.
Director, Adult Attention Deficit Disorder Center of Maryland
Assistant Professor, Johns Hopkins University School of Medicine, Department of Psychiatry and Behavioral Sciences
Historically, attention deficit hyperactivity disorder has been conceptualized as a neurodevelopmental disorder. In this case, neurodevelopmental is defined as the evolution of symptoms occurring as the brain ages. As the brain’s neural network changes and matures, symptoms change or possibly diminish until they "go away". This concept is particularly relevant to attention deficit hyperactivity disorder because up to 50% of children with ADHD will continue to have symptoms in adulthood. Conversely, 50-60% of the ADHD children do not have functionally impairing symptoms in adulthood.
What factors determine which children continue to have symptoms in adulthood?
At this time we do not have clear answers to this question. Research suggests a strong familial pattern which we presume reflects a genetic component. Genetic factors account for 80%. 30% of parents with ADHD children have the disorder. In contrast, ADHD only rises in 4% of children of non-affected adults. ADHD children whose parents have adult ADHD symptoms will be at greater risk for having symptoms persist into adulthood. Adults whose ADHD symptoms remitted in adolescence may have children whose ADHD symptoms also remit in adolescence. Therefore, the child’s risk for adult manifestations may be predicated on the affected parent’s ADHD illness history. The clarification of this issue might better define the "genetic load" for the disorder. Psychosocial adversity and psychiatric co-existing disorders are also risk factors for the persistence of ADHD into adulthood.
How do cognitive symptoms and hyperactivity change with age in an affected individual?
In the adult ADHD patient, the cognitive deficits seem not to change with age. The persistence of inattention/distractibility become the impairing symptoms for an adult dealing with increasing adult responsibilities. In contrast, hyperactivity seems to decline with age. This has been found in children followed into late teens and early twenties. The change in the appearance of hyperactivity may be a reflection of neurodevelopment or a psychosocial process. Neurodevelopmentally, the maturation of the brain may reduce motor activity itself. Psychosocially, a person may redirect their hyperactivity into socially acceptable channels. It is very likely that both processes occur in most adult ADHD patients. Understanding the evolution of symptoms becomes an important concept when applying diagnostic criteria to adults.
ADHD is supposed to "go away" in mid-adolescence. What’s up?
Because physicians so strongly believed this disorder remitted in adolescence, no one thought to follow the patients into adulthood to see if symptoms persisted. Paul Wender, M.D. at the University of Utah was perhaps the first researcher to follow and publish his findings about the adult ADHD patients. His writings started to appear approximately twenty years ago. The recognition of this disorder is relatively new and research is now rapidly emerging.
Two diagnostic concepts are important to understand when reviewing symptoms of this disorder. One is differential diagnoses and the other is comorbid disorders. Differential diagnoses are a list of disorders to be considered when the grouping of symptoms are consistent with another diagnosis. For example, the symptoms of mood reactivity, impulsivity, irritability, and poor attention, although suggesting ADHD, may actually be a bipolar disorder (manic-depressive illness). This grouping of symptoms may also suggest a borderline personality disorder. You can see how this might create confusion when a few symptoms fall in several diagnostic categories.
Yes, but what if I just focus on the symptoms of inattention and distractibility to make the diagnosis?
Well, attentional levels vary within an individual and are influenced by a number of factors including diurnal variation (changes over the 24 hour cycle), sleep patterns, anxiety, stress, age, mood or medication. If you were to focus on inattention/distractibility, you would still have to consider other disorders before considering ADHD. In addition, learning disabilities frequently occur with ADHD making the evaluation of cognitive impairments specifically related to ADHD that much more difficult.
Diagnostic accuracy is crucial to formulating treatment recommendations. Focusing on pharmacologic therapy, a specific medication(s) will be recommended because it best addresses the diagnosis and associated symptoms. For example, the patient diagnosed as ADHD may be prescribed dextroamphetamine for disorganization, impulsivity, mood reactivity, inattention, hyperactivity and poor judgment. A week later the patient’s spouse calls and tells the physician that the symptoms have gotten worse. The patient is not sleeping or eating, recklessly spending money, and believes that his coworkers are plotting against him. One might conclude that the patient’s symptoms were provoked by too much stimulant, leading the physician to stop the dextroamphetamine. However, this patient may have an undiagnosed bipolar disorder that got worse from the dextroamphetamine. Stopping the dextroamphetamine will not be adequate treatment. Patient needs to be treated with an mood stabilizer and anti-psychotic. This situation could easily result in hospitalization for the patient, the ramifications of which are tremendous.
I mentioned earlier a second concept, comorbid disorders. When two or more disorders exist simultaneously, they are considered comorbid. Researchers look for frequent association between medical disorders because it may give them a clue to a common mechanism and thereby lead them to more effective treatments. Comorbid disorders occur more frequently in the ADHD adults than children with ADHD. In one study, only 25% of the adult ADHD population were "pure", that is , no comorbid conditions. So, 75% of these adults have at least one additional psychiatric diagnosis. In children, the comorbid rate is 50%. One explanation for a higher comorbid rate in adults is the fact the peak onset age range for mood and anxiety disorders is late teens and early twenties. Simply said, the ADHD child isn’t yet old enough to show symptoms of adult psychiatric disorders.
How do we know about the comorbid disorders in ADHD?
J. Biederman, M.D. at Harvard Medical School wrote an article with his research colleagues in the American Journal of Psychiatry in 1993 addressing this issue. In his paper, he look at two groups of ADHD adults, (referred ADHDs and nonreferred ADHDs), and compared them to adults without the ADHD. The comorbid illness rates were significantly different when comparing the two groups of ADHD adults to adults without ADHD. Comorbid disorders occurred at similiar rates among patients within the two groups of adult ADHD suggesting validilty of comorbid disorders in ADHD adults. The similiar comorbid rates occurred regardless of whether the ADHD patient was referred for treatment or not. This finding helps eliminate the selection bias introduced when only looking only at patients who seek treatment. Subsequent research has confirmed these findings.
What other disorders should we consider?
There are specific psychiatric disorders that seem to have significant rates of comorbidity. In Dr. Biederman’s study, generalized anxiety disorder occurred in 20-36% of the ADHD adults, multiple anxiety disorders 42%, clinical depression (Major Depression) 30%, Bipolar Disorder 10%, alcohol/drug abuse 36-41%, social phobia 33-27%, antisocial personality disorder 18-10%. These percentages are conservative compared to other studies reporting higher comorbid rates. Other studies have reported mood disorder comorbidity occurring up to 57%. These high rates of comorbidity were also found by Shekim et al. (1990). In children with ADHD, longitudinal studies have reported increased risk for mood or anxiety disorders.
If several disorders exist together, which disorder do we treat first?
This is an excellent question and one only recently answered by published research. As mentioned earlier, a misdiagnosis or the presence of an unrecognized psychiatric disorder may lead to treatment that is ineffective or harmful. In a personal communication to me, both Dr. Biederman and Dr. Wilens at Harvard suggest that any mood disorder be stabilized first before the pharmacologic treatment of ADHD is undertaken. This has been our mode of treatment for several years. This position is in contrast to the Texas Algorithm for the treatment of co-existing conditions. The algorithm was a consensus of paneled experts specifically addressing treatment in children and adolescents. The Texas Algorithm suggested treating ADHD first and then evaluating the presence of other conditions. With the recent focus on Bipolar Disorder in children, the treatment of children with ADHD and comorbid conditions is changing. Experts now suggest that comorbid psychiatric disorders be treated first followed by the treatment of ADHD.
It is essential that all existing psychiatric conditions be accurately identified, then prioritized for treatment so that a thoughtful sequence of medication trials can be instituted. Because the first medication trial may not be successful, it is necessary for the physician to document any partial response and notable side effects occurring with each medication. This allows for the accumulation of data that will increase the likelihood of finding the right medication or combination. When comorbid disorders exist, medication combinations may be necessary. The combination may be more effective than a single medication. I reviewed the medication alternatives for ADHD adults during my presentation at the Eleventh Annual National Children and Adults with Attention Deficit Hyperactivity Disorder Association(CHADD) Conference on Friday, October 8, 1999 in Washington, DC. This presentation is available on videotape from CHADD in Landover, Maryland.
The diagnosis of adult attention deficit hyperactivity disorder is very complex. The clinician needs to consider differential diagnoses before reaching a diagnostic conclusion. Then the presence of comorbid conditions needs to be reviewed by asking specific questions. Only after a comprehensive evaluation is completed can the issues of medication be considered. Research on treatment algorithms for comorbid conditions is still in its infancy. The continuing emergence of research findings and the refinement of the clinical skills of health professionals will improve the accuracy of diagnoses and treatment.
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