Attention-deficit/hyperactivity disorder (ADHD) receives considerable attention in both medical literature and the lay media. Historically, ADHD was considered to be primarily a childhood condition. However, recent data suggest that symptoms of ADHD continue into adulthood in up to 50 percent of persons with childhood ADHD.¹, ^2(pp41–75) Because ADHD is such a well-known disorder, adults with both objective and subjective symptoms of poor concentration and inattention are likely to present to family physicians for evaluation. While the symptoms of ADHD have been extended developmentally upward to adults, most of the information about the etiology, symptoms and treatment of this disorder comes from observations of and studies in children. Research on adult ADHD is in an early stage. The criteria for ADHD emphasize a childhood presentation, and there is growing evidence that the diagnostic features of ADHD take a different form in adults.

For several reasons, family physicians may be uncomfortable evaluating and treating patients with symptoms of ADHD, particularly adults without a previously established ADHD diagnosis. First, the criteria for ADHD are not objectively verifiable and require reliance on the patient's subjective report of symptoms. Second, the criteria for ADHD do not describe the subtle cognitive-behavioral symptoms that may affect adults more than children. Third, the most effective treatment is long-term use of a schedule II drug with potential for abuse.³

The family physician's role as diagnostician is further complicated by the high rates of self-diagnosis of ADHD in adults. Many of these persons are influenced by the popular press. Studies of self-referral suggest that only one third to one half of adults who believe they have ADHD actually meet formal diagnostic criteria.⁴ While family physicians are knowledgeable about childhood ADHD, there is a noticeable absence of guidelines for primary care evaluation and treatment of adults with symptoms of the disorder.

Diagnostic Criteria and Symptoms

The criteria for ADHD as specified in the Diagnostic and Statistical Manual of Mental Disorders, 4th ed. (DSM-IV), are described in Table 1.⁵ DSM-IV describes three subtypes of the disorder: predominantly hyperactive, predominantly inattentive and a mixed type with symptoms of the other two forms. Symptoms should be persistently present since age seven. While a longstanding symptom history is often difficult to elicit clearly in adults, it is a key feature of the disorder.

Adults who have retained some, but not all, of the symptoms of childhood ADHD may be best diagnosed as having ADHD in partial remission.^5,6 While the DSM-IV criteria for ADHD may be applied to adults, these dimensions tend to reflect presentations in children. The subtlety of ADHD symptoms among adults has led to several modifications of existing criteria. Rather than requiring six DSM-IV symptoms of inattention or hyperactivity, some investigators propose requiring only five such behaviors for older patients.⁷ In addition, the symptoms take different forms in adults.

There is growing consensus that the central feature of ADHD is disinhibition.⁸ Patients are unable to stop themselves from immediately responding, and they have deficits in their capacity for monitoring their own behavior. Hyperactivity, while a common feature among children, is likely to be less overt in adults. The “on the go” drivenness seen in many ADHD children is replaced in adults with restlessness, difficulty relaxing and a feeling of being chronically “on edge.”¹

Deficits in sustained attention and concentration are likely to remain and may become more apparent in late adolescence and early adulthood as responsibilities increase. Appointments, social commitments and deadlines are frequently forgotten. Impulsivity often takes the form of socially inappropriate behavior, such as blurting out thoughts that are rude or insulting. While many of the symptoms are reported by others in the patient's life, the problem often expressed by adults with ADHD is frustration over the inability to be organized.¹ Prioritizing is another common source of frustration. Important tasks are not completed while trivial distractions receive inordinate time and attention.

Wender developed a set of ADHD criteria, referred to as the Utah criteria, that reflect the distinct features of the disorder in adults (Table 2).^{2(pp122–43)} The diagnosis of ADHD in an adult requires a longstanding history of ADHD symptoms, dating back to at least age seven. In the absence of treatment, such symptoms should have been consistently present without remission. In addition, hyperactivity and poor concentration should be present in adulthood, along with two of five additional symptoms: affective lability; hot temper; inability to complete tasks and disorganization; stress intolerance; and impulsivity.

The Utah criteria include the emotional aspects of the syndrome. The episodes of hot temper, typified by frequent angry eruptions out of proportion to the precipitants, often “blow over” more quickly for the patient than for coworkers and family members. Affective lability is characterized by brief, intense affective outbursts ranging from euphoria to despair to anger, and is experienced by the ADHD adult as being out of control. Under conditions of increased emotional arousal from external demands, the patient becomes more disorganized and distractible.^{2(pp122–43)}

Another model of adult ADHD diverges from DSM-IV but overlaps with Wender's criteria and includes five areas.⁹ In this model, the five core ADHD dimensions include the following: activation and organization; sustained attention; sustained energy and effort; managing affective interference; and working memory and accessing recall. Activation refers to difficulties initiating and organizing daily tasks. Sustained attention includes such aspects as distractibility, daydreaming and having to reread material to understand it. Sustained energy and effort refers to drowsiness, inconsistent performance and poor task completion. Managing affective interference includes difficulty managing criticism as well as being easily frustrated, irritable and poorly motivated. Memory difficulties encompass recent and remote memory for daily activities and task-related materials.⁹

Another model, which serves as the basis for the Copeland symptom checklist for ADHD in adults, includes eight dimensions: inattention and distractibility; impulsivity; activity level problems; noncompliance; underachievement, disorganization and learning problems; emotional difficulties; poor peer relations; and impaired family relationships.¹⁰

Evaluation

The subtlety and subjectivity of ADHD symptoms in adults, together with the absence of a single “gold standard” for confirming the diagnosis, make assessment particularly challenging. Evaluation of adults with symptoms of ADHD requires weighing and integrating a range of data, including the patient's history, the patient's self-report of symptoms and mental status testing (Table 3). A thorough history should include an emphasis on past school performance and conduct, previous and current psychiatric therapies, and reports of specific symptoms of inattention, distractibility and disorganization. ADHD is currently understood as a neurobehavioral condition that is typically apparent in preschool years and becomes more pronounced in the early elementary grades.

An extended, consistent pattern of ADHD symptoms, dating back to early childhood, should be uncovered during history taking. Patients with ADHD may have difficulty accurately recalling relevant history.¹¹Adult patients should be asked to provide any available school records and gather information from parents and other adults who knew them as children. Because adults with ADHD may not appreciate their symptoms, the patient's spouse or another significant person in the patient's life should ideally be included in the interview. The recent onset of symptoms or sporadic episodes of symptoms should raise concern about the appropriateness of the diagnosis of ADHD.

The three most commonly used self-report measures for ADHD are the Wender rating scale,¹² the Copeland symptom checklist and the Brown scale (Table 4). While self-report instruments may be useful for initial screening, they should not be used alone to diagnose adult ADHD. High scores are likely in a variety of psychiatric conditions. Problems with attention, concentration, affective lability, impulsivity and task completion are non-specific and can be associated with many forms of psychopathology.

Mental status testing is often useful when evaluating the patient's cognitive functioning in the office, but impaired performance on mental status testing may result from numerous psychiatric and medical conditions. Cognitive tasks include recitation of serial 7s for assessment of concentration, digit span forward and backward for assessment of attention, and immediate recall for assessment of short-term memory. Short-term memory can be evaluated by asking patients to verbally recall a short paragraph that was read to them. The patient's ability to attend to relevant stimuli while ignoring distractions can be assessed through vigilance tasks in which the patient is read a string of letters and told to tap a finger when a target letter is spoken. Verbally administered mathematic problems are more demanding tasks that require concentration and problem solving.

The medical evaluation should include a neurologic examination. There are suggestions that patients with ADHD exhibit a greater incidence of “soft neurologic signs,” including problems with right-left discrimination, motor overflow movements and sequencing difficulties.¹³ Laboratory tests may include a serum lead level and thyroid function tests.^13,14

Differential Diagnosis

Patients with a range of psychiatric conditions may emphasize difficulty with concentration, attention or short-term memory when they describe their problems to the physician.¹⁴ It is important to exclude other psychiatric conditions, most of which are actually more prevalent than ADHD among adults (Table 5). Major depression and substance abuse, in particular, commonly accompany adult ADHD.

Importantly, most adults with ADHD do not have a “pure” form of the disorder. Comorbidity is more likely to be the rule than the exception. It is not clear whether these comorbid psychiatric conditions are a psychologic effect of preexisting ADHD or are simply associated with ADHD.² For example, substance abuse may have developed as a way to reduce the frustration arising from distractibility, inattention and impulsivity. If a comorbid psychiatric disorder exists in a patient with ADHD, the patient should be educated about the ADHD symptoms that will resolve with stimulant therapy and the symptoms of the other psychiatric condition that may warrant additional treatment.

In addition to the physical examination and laboratory findings, a thorough history is valuable in the differential diagnosis. Medical conditions that may mimic adult ADHD include hyperthyroidism, petit mal and partial complex seizures, hearing deficits, hepatic disease and lead toxicity.¹³ In addition, sleep apnea and drug interactions should be considered as possible causes of inattention and hyperactivity.^13,15 Patients with a history of head injury may also have problems with attention, concentration and memory.¹⁶

Pharmacotherapy

STIMULANTS

The pathophysiologic basis of ADHD centers on an imbalance in catecholamine metabolism in the cerebral cortex, and the agents used to treat this disorder in adults, as in children, enhance the availability of dopamine and norepinephrine.^17,18 Pharmacotherapy options are summarized in Table 6. As with children, stimulants are the most commonly used category of medications in adults with ADHD.

Methylphenidate (Ritalin) and dextroamphetamine (Dexedrine) are effective in improving attention and concentration, and in reducing impulsivity in adults with ADHD.¹⁸ Although chemically distinct from the other two agents, pemoline (Cylert) has a mechanism of action that is similar to that of methylphenidate and dextroamphetamine. These agents stimulate the release of catecholamines from storage sites at the synapses of the central nervous system. Because catecholamine receptors are pervasive throughout the central nervous system, the exact focus of the pharmacologic effect is unclear. Increased norepinephrine and dopamine concentrations in the brain stem, midbrain or frontal cortex have been postulated to be responsible for the increased attention span and concentrating ability that occurs with the use of stimulants. Because stimulants may produce these effects in patients without ADHD and because not all patients with ADHD improve with such therapy, the patient's response cannot be used to confirm or exclude the diagnosis of ADHD.³

Each of the currently available stimulants appears to be equally effective in the management of symptoms of ADHD, but they differ in their time course of action. Stimulants are usually well tolerated and are associated with only mild side effects. A common initial side effect is sleep disturbance, characterized by the delayed onset of sleep. While initial insomnia can be a side effect of stimulant medication, it is also a common complaint of adults with untreated ADHD. Therefore, if sleep problems develop after initiation of therapy, it may be helpful to assess the patient's sleep patterns for several weeks before altering the dosage or the timing of administration. Another side effect of stimulants may be a decrease in appetite, resulting in weight loss.

The cardiovascular effects of stimulants are of potentially greater concern in adults than in children. Mild increases in heart rate and blood pressure may occur but are not usually clinically significant.¹⁹ Because the effects of stimulants on blood pressure may be variable, blood pressure should be controlled and closely monitored when initiating treatment with stimulants in patients with hypertension.²⁰

Because of the risk of hepatitis with pemoline, the use of this agent is recommended only in patients who have failed to respond to other stimulants.¹⁸ A baseline serum alanine aminotransferase (ALT) determination should be obtained before initiating therapy with pemoline and every two weeks during therapy. According to the manufacturer, pemoline therapy should be discontinued if the ALT level exceeds two times the upper limits of normal or if symptoms of liver disease develop. The manufacturer of pemoline has developed a consent form that describes the risks associated with this drug and recommends that patients sign the form before initiation of therapy.

Some prescribing issues surround the use of controlled substances such as stimulants. Caution should be exercised not only in making the diagnosis of ADHD but also in avoiding the use of stimulants in patients with a history of substance abuse. On the other hand, adult patients may require larger dosages than those usually prescribed to children. Therefore, it is important to document the patient's symptoms and the patient's response to each dosage as the amount is titrated upward. Because methylphenidate and dextroamphetamine are C-II controlled substances, most states limit prescriptions to a 30-day supply and do not authorize refills. In addition, written copies of the prescription are usually required. Such requirements necessitate frequent contact between the patient and physician for reevaluation and prescription renewal. Pemoline is classified as a C-IV controlled substance, which can usually be refilled up to five times over the six months following the initial prescription.

ANTIDEPRESSANTS

As a means of increasing the concentration of catecholamines in the central nervous system, antidepressants that inhibit reuptake of norepinephrine have been evaluated for the treatment of ADHD.¹⁷ Tricyclic antidepressants (TCAs), which inhibit the uptake of norepinephrine and serotonin, may be effective, while the response to selective serotonin reuptake inhibitors (SSRIs) has been less promising in adults with ADHD.^18,21 The secondary amine TCAs, such as desipramine (Norpramin) and nortriptyline (Pamelor), may be preferred because of greater effects on norepinephrine than on serotonin and a better side effect profile.¹⁷ Bupropion (Wellbutrin), an atypical antidepressant with more stimulant properties than the TCAs, may be effective as well.¹⁷ Therapy with monoamine oxidase (MAO) inhibitors has produced variable responses in patients with ADHD, but may be tried in patients who have responded poorly to other therapies.

Antidepressant therapy in adults with ADHD may be particularly helpful in reducing affective instability and controlling a coexistent mood disturbance. Because of the different effects of stimulants and antidepressants, some patients may benefit from the combination of a stimulant and an antidepressant.

Adverse effects of antidepressants often limit the ability to titrate the dose to an effective level. Because of the possibility of cardiac conduction abnormalities, an electrocardiogram should be obtained before initiating TCA therapy and after the dosage is stabilized. Drowsiness is common but may be minimized by taking the antidepressant at bedtime and slowly titrating to the target dosage. Anti-cholinergic effects such as dry mouth, constipation and urinary retention may also be troublesome. Weight gain and postural hypotension may be problematic. Sexual dysfunction is more common with the agents that affect serotonin reuptake, so it may be less common with secondary amine TCAs. If sedation is problematic, bupropion may be an alternative agent. However, the use of bupropion is contraindicated in patients with a history of seizures. If an antidepressant is tolerated at an effective dosage, it may be a reasonable alternative in patients with coexisting depression or an alternative to a controlled substance.

OTHER MEDICATIONS

Sympatholytics have also been used in the management of ADHD. Clonidine (Catapres) is a centrally acting alpha ₂ agonist that decreases sympathetic outflow from the central nervous system. While this agent may be beneficial in children and adolescents, particularly those with significant hyperactivity and aggressive behavior, the benefits in adults are less clear. Sedation is the most common adverse effect of clonidine. The antihypertensive effects of clonidine may be beneficial in a patient with hypertension but may limit its usefulness in other patients.

Self-Management Strategies

Adults with ADHD benefit considerably from direct education about the disorder. They can use information about their deficits to develop compensatory strategies. Planning and organization can be improved by encouraging patients to make lists and use computerized schedules. Placing a large calendar with important dates and deadlines in a central location in the home or workplace is a valuable memory aid.²⁰ Ways to reduce distractions may include having a clutter-free desk, a carrel-style desk or a windowless office. ADHD adults may benefit from going to work early to accomplish tasks before coworkers arrive and phones begin ringing. Most adults are aware of their “personal clock” and know their prime times for completing intellectually demanding tasks. Task completion can be improved by systematically breaking down large projects into manageable “chunks,” each with its own deadline.²⁰

Adults with ADHD should be educated about their elevated risk for drug and alcohol dependence and should be encouraged to drink in moderation or practice abstinence.

Psychotherapy

Marital and individual counseling and self-help groups are often valuable adjuncts to pharmacotherapy and skill training. Among newly diagnosed adults in particular there may be an extended psychologic history of low self-esteem, failure, frequent job changes and relationship problems. Individual psychotherapy that focuses on core issues of self-worth along with ways to improve the patient's ability to monitor work and social skills can be invaluable.

Married patients often have significant relationship conflicts stemming from forgotten commitments, impulsive decisions and emotional outbursts. Working with the couple to enhance communication skills, conflict resolution and problem solving, and educating the patient's spouse about ADHD can dramatically improve the relationship.²⁰ Finally, self-help organizations such as Children and Adults with Attention Deficit Disorder (CHADD; 800-233-4050) provide didactic information about the disorder.