By Andrew Feinberg, M.D.
Corrected version of article which appeared in the Fall 1997 issue of Smooth Sailing, a quarterly newsletter published by Depression and Related Affective Disorder Association (DRADA), Johns Hopkins University, Department of Psychiatry, Baltimore, Maryland
Mood disorders and ADHD coexist often enough that knowledge of ADHD should be of interest to many readers of Smooth Sailing. According to research by Dr. Joseph Biederman and colleagues, 17 to 30 percent of adults with ADHD also have major depression, and 5 to 10% of them have bipolar disorder. Certainly clinicians who have expertise in diagnosing and treating individuals with mood disorders will recognize the symptoms of ADHD in some of their patients once the mood disorder has been stabilized. With patients who initially have symptoms of both a mood disorder and ADHD, treatment of the mood disorder should be optimized before medication for ADHD is considered.
As for other mental disorders, a psychiatrist uses guidelines in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) in evaluating an adult for the possible presence of ADHD. This manual contains diagnostic criteria for three types of ADHD: combined, predominantly inattentive, and predominantly hyperactive-impulsive.
By several published estimates of prevalence, 3 to 5 percent of children and adolescents have ADHD. Forty to 60 percent of children with ADHD continue to complain of symptoms of ADHD as adults, and 11 to 31 percent of these adults continue to have disabling symptoms. We can estimate that between 1 and 3 percent of the general adult population has ADHD. For comparison, the prevalence of bipolar disorder is estimated to be 1 percent and that of major depression, 5 percent.
As with mood disorders, there is evidence that ADHD has a genetic basis. The evidence is derived from twin studies in which concordance rates [percentages of twin pairs sharing a trait, such as ADHD] are compared for identical and fraternal twin pairs, and by adoption studies (which control for possible environmental contributions for ADHD). When evaluating a patient with symptoms and signs of ADHD, as when evaluating a patient with a mood disorder, it is very useful to get a family history.
Studies involving PET positron emission tomography] scans have provided evidence that regional brain perfusion [blood flow] and metabolism differ in adults with and without ADHD. Specifically, frontal regions of the brain appear to be less active in adults with ADHD; this finding is interesting and relevant because these regions of the brain are normally involved in inhibition of thought, mood, and activity. Even though PET scans are used as a tool in ADHD research, they are not a clinical diagnostic test.
In some respects, approaches to managing adults with ADHD are similar to those used with mood disorder patients. Education about the illness is critical, as are support groups. Like DRADA, CHADD (Children and Adults with ADD, a national, state, and local organization) provides support and education. Successful treatment of ADHD in adults requires psychotherapy, often involving spouse and family. Frequently, the assistance of a "coach" (possibly a friend or colleague is helpful also. The primary medications used in treating ADHD are stimulants: methylphenidate (Ritalin), dextroamphetamine (Dexedrine), a mixture of amphetamine and dextroamphetamine (Adderall), and pemoline (Cylert). These medications differ mainly in their time to onset of action and their duration of action. Just as with the medications used in treating mood disorders, medications for ADHD have side effects, potential interactions with other medications, and potential impacts on other illnesses. They should, therefore, be administered by physicians familiar with their appropriate use.
In conclusion, a psychiatrist evaluating someone who may have ADHD must take a comprehensive history, consider the differential diagnosis (rule out other disorders with similar symptoms and signs), consider the possible presence of comorbid [co-existing] conditions (such as a mood disorder), and present a thoughtful, individualized treatment plan.
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