Marlin D. Wiita, PA-C

Attention-deficit/hyperactivity disorder (ADHD) was once thought to be limited to overactive or inattentive children. Yet recent studies have shown that ADHD has a 50% to 60% persistence rate into adulthood and may affect as many as seven million adults in the United States today, impairing the ability of many to function productively.^1,2 A significant number of adolescents previously diagnosed with ADHD but not currently receiving treatment are emerging into young adulthood. Some patients are prompted to seek help when their ADHD symptoms interfere with daily functioning; in others, ADHD is identified when they seek treatment for other conditions.

Most older ADHD patients initially present in the primary care setting,³ where practitioners may be reluctant to treat them because:

(1) The diagnosis of ADHD is subjective and purely clinical.

(2) It is unclear how the presently published diagnostic criteria should be applied to adults.

(3) The ADHD treatments proven most effective are schedule II psychostimulants, which have a certain potential for abuse.⁴

This article summarizes a review of currently accepted practice in primary care for recognizing and treating ADHD in the young adult patient.

Background
Between 1990 and 1998, the number of school-age children diagnosed with ADHD reportedly increased by 700%.⁵ The accompanying increase in use of schedule II stimulants⁶ (primarily methylphenidate and dexamphetamine) aroused some controversy, even though these medications were shown to be effective in reducing the inattentiveness, impulsivity, and hyperactivity associated with ADHD.^7,8

Concerns regarding the indicated medications—possible abuse, associated adverse effects, inconvenience, stigma—prompted many parents of affected children to decline pharmacologic treatment.⁹ Among treated children, a large proportion discontinued their medications because they did not have a response or experienced intolerable adverse effects.^10,11 Still others were never diagnosed. As a result, a significant number of adolescents with untreated or undertreated ADHD are now entering adulthood. Without treatment now, perhaps half of them will experience lifelong impairment resulting from ADHD and associated comorbidities (ie, conduct and oppositional-defiant disorder, antisocial personality disorder, substance abuse disorder, anxiety disorders, and depression).^1,2,9,10,12

ADHD is believed to have a solid neurobiologic basis, but the condition has no known objective markers. Its diagnosis remains subjective and clinical, depending primarily on structured interviews conducted by trained practitioners.¹³ Unlike most behavioral disorders, which are first understood in adults, then extrapolated to children,¹⁴ ADHD has been recognized and treated in children since the late 1930s¹⁵ but has only recently been identified among significant numbers of adults.¹ Thus, ADHD is currently best understood in children.¹⁴

The classic symptoms and signs of ADHD and its subtypes undergo subtle alterations as the patient matures.^2,12,16 Hyperactivity wanes in adolescence and may be replaced by a restlessness that prompts the adult patient to change jobs and/or living quarters frequently, leading to an unstable lifestyle.¹² Although impulsivity and inattention may persist through adolescence into adulthood, they are often obscured by both coping mechanisms (eg, choice of employment, conscious efforts by high achievers to overcome their disorganization)1 and behavioral comorbidities (depression, self-medication/substance abuse, personality disorders) that the patient may have developed.^10,16 These developments may significantly complicate identification of the disorder in older patients.^2,12,10,16

The adult with ADHD often exhibits low self-esteem, anxiety, depression, sleep disturbances,¹⁷ difficulties with personal relationships and jobs, and impulsivity, which can lead to trouble with the law.¹⁸ The costs to adult ADHD patients, their families, and the community are enormous, making it all the more important for health care professionals to understand this condition.

Diagnostic Criteria
The diagnosis of ADHD is based on criteria from the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition^7,19(DSM-IV; see www.cdc gov/ncbddd/adhd/symptom.htm). ADHD may be widely acknowledged to affect adults, but only recently has an attempt been made to modify the DSM-IV criteria to accommodate the adult patient; changes so far have been limited to minor rewording. As the DSM-IV undergoes significant change at a conservative pace, individual practitioners must decide how best to apply the current criteria to adult patients.

Modifying the DSM-IV Criteria
Adult ADHD is a relatively new diagnostic category. Creating such categories to account for the symptoms of less impaired patients incurs the risk of ascribing pathology to conditions that lie at the margins of normality; hence the reluctance of DSM-IV editors to engage in rapid change. Weighed against their conservative approach, however, is the opportunity to treat individuals whose lives would benefit as a result. Thus, the editors of DSM-IV encourage its use as a guideline rather than a “cookbook.”²⁰ The further practitioners move away from the comorbidities of mental health toward the merging of “soft” morbidity with normality, the more flexibility is required in applying the DSM-IV criteria.

For example, for a diagnosis of adult ADHD, one DSM-IV requirement is for the patient to have experienced onset of symptoms by age 7 (perhaps to distinguish it from confounding comorbidities that develop during or after adolescence). This seems unnecessarily restrictive and can be difficult to establish retrospectively. Even careful history-taking can be insufficient, as third-party observers are likely to be unavailable.^9,13 Although recent studies have shown adult self-determined questionnaires to be an effective means of detecting ADHD impairment during childhood, many practitioners continue to question their validity.²¹ Proposals have been made to modify this age requirement, but agreement has not been reached on a new cutoff point (if one should be specified at all).

Because many “subthreshold” patients might benefit from pharmacotherapy, it has been suggested that the currently required number of DSM-IV criteria (six) should be relaxed. But what should that number be? Requiring only three criteria, researchers recently found, would result in 25% of all presenting patients qualifying for a diagnosis of ADHD.²² Most experts agree that a corresponding increase in psychostimulant use would be unjustified.

The willingness of practitioners to use the current DSM-IV criteria flexibly (eg, deciding what comprises a “clinically significant impairment”) will be determined by their level of comfort in diagnosing DSM-IV–defined disorders. Until continued research can provide more definitive diagnostic criteria for the adult with ADHD, a conservative approach may be advisable to avoid medicating patients unnecessarily.

Supplemental Rating Scales
Experts have developed several rating scales which, while not diagnostic, are nonetheless useful in identifying the adult who is impaired by ADHD but who may not strictly meet the DSM-IV criteria. These include:

• Wender Utah Rating Scale for Adult ADHD.^23,24 One of the earliest and still most useful adjunctive rating scales for adult ADHD,²³ this tool was originally developed to retrospectively identify childhood onset (before age 7) of ADHD symptoms. The original 61 items have been condensed and reorganized into a 25-item self-assessment questionnaire (see Table 1^23,24). The currently used Wender Utah scale seeks to elicit from the adult patient the core symptoms of ADHD.²⁵

• Conners’ Adult ADHD Rating Scales (CAARS).²⁶ This proprietary, 93-question, structured clinical interview allows the clinician to determine the presence of DSM-IV–defined symptoms of ADHD.²⁷ Questions are grouped into nine symptom domains thought to encompass ADHD in adults, with responses categorized into four distinct problem areas²¹ (see Table 2^21,26,27). Although problematic responses appear to correlate highly with confirmed ADHD, a 15% misdiagnosis rate prevents use of the CAARS for definitive diagnosis.²¹

• Brown ADHD Rating Scale for Adults.²⁸ This tool identifies five important symptom clusters (see Table 3^21,28). The Brown scale overlooks hyperactivity in adults and instead emphasizes executive functioning.

• Adult ADHD Self-Report Scale (ASRS-v1.1).²⁹ This self-administered questionnaire, developed through the World Health Organization, assesses for 18 DSM-IV–designated ADHD symptoms, with the first six items found most predictive. If four of these six items are “scored” (ie, the patient responds “Often” or “Very often”), the assessment is considered highly consistent with adult ADHD, and further investigation is warranted. (For seven of the 18 items, an answer of “Sometimes” is also scored. See Table 4.²⁹) Items 7 through 18 provide additional cues to distinguish specific symptoms or impairments.

No consensus exists regarding the reliable use of these rating scales to assist in the diagnosis of adult ADHD. As mentioned earlier, the role of patient self-reported symptoms of ADHD is subject to lingering controversy.²⁷

ADHD Subtypes
Many practitioners find it aids diagnosis to divide ADHD into the subtypes shown in Table 5^19,27; subtypes 4 and 5 are often applicable in this patient population. According to Robison et al,³⁰ however, women with ADHD are more likely to have the combined type (subtype 3) than men are (75% vs 62%, respectively), have a more complex presentation, and display greater impairment than men on all measures of ADHD symptoms.

Promise of Biomarkers
The neurobiologic basis of ADHD is poorly understood. Since medications known to have beneficial effects in ADHD alter dopamine levels,³¹ one prominent theory attributes the condition to dysfunction of dopamine neurotransmission and subsequent disruption of dopamine-modulated circuits among the frontal, striatal, and limbic regions of the brain.³² Early imaging studies using radioligands have shown a 70% increase in levels of the dopamine transporter molecule among subjects with ADHD, compared with non-ADHD controls.³³ Subsequently, however, dopamine levels have been found to vary among subregions of the brain, suggesting that the explanation is probably more complex.^32-34

ADHD medications also alter regulation of norepinephrine and possibly serotonin.³¹ The interplay in the brain between norepinephrine and dopamine is complex, and investigation of these processes is hampered by the current lack of a suitable radioligand that will bind selectively to the norepinephrine transporter molecule.³⁵ Until an objective marker for ADHD is identified, the diagnosis of ADHD remains subjective and purely clinical.  

Treatment
Current treatment recommendations for adult ADHD are almost exclusively pharmacologic. Effective, FDA-approved agents are methylphenidate, dextroamphetamine, and the nonstimulant atomoxetine. Treatment efficacy is determined by patient response, which is far from uniform or predictable. Selecting the optimal drug and dosage for each patient can be a lengthy process. Off-label use of other pharmacologic agents (eg, bupropion, clonidine, modafinil, and the tricyclic antidepressants³¹), combinations of agents, and medication for the ADHD patient with a history of substance abuse are treatments that are best left to a specialist.

Until recently, the role of behavioral therapy for children with ADHD had been somewhat discounted.³⁶ In current research, behavioral therapy appears to help properly motivated adult patients understand their condition and develop appropriate coping skills.³⁷ Self-referred adults with ADHD are usually motivated and compliant with prescribed treatment regimens.³

Currently, few therapeutic options are available for the ADHD-impaired adult who does not meet DSM-IV criteria for stimulant medications. If adults with confirmed ADHD benefit from behavioral therapies, however, their use to treat less impaired, subthreshold ADHD adults (for whom pharmacotherapy may not be warranted) is an intriguing possibility.

Conclusion
Previously considered a childhood-only disorder, ADHD is now known to persist into adulthood in many cases, often causing significant impairment in affected individuals. Ongoing research and brain imaging studies continue to improve our understanding of the neurobiologic basis for ADHD. Since no biomarker has yet been proved valid, diagnosis of ADHD remains subjective and clinical.

No consensus exists regarding the best diagnostic tools for ADHD in the young adult. Applying the DSM-IV criteria for ADHD to the adult patient is controversial. Until more objective data make it possible to modify these criteria, the primary care practitioner must rely on supplemental rating scales and other tools to gather diagnostic information.

Currently, schedule II stimulants and the FDA-approved nonstimulant atomoxetine are the most effective agents known for the adult patient with ADHD. Off-label medication use, combinations of medications, and the addition of behavioral therapy are best handled by a specialist.    

Attention-deficit/hyperactivity disorder (ADHD) was once thought to be limited to overactive or inattentive children. Yet recent studies have shown that ADHD has a 50% to 60% persistence rate into adulthood and may affect as many as seven million adults in the United States today, impairing the ability of many to function productively.^1,2 A significant number of adolescents previously diagnosed with ADHD but not currently receiving treatment are emerging into young adulthood. Some patients are prompted to seek help when their ADHD symptoms interfere with daily functioning; in others, ADHD is identified when they seek treatment for other conditions.

Most older ADHD patients initially present in the primary care setting,³ where practitioners may be reluctant to treat them because:

(1) The diagnosis of ADHD is subjective and purely clinical.

(2) It is unclear how the presently published diagnostic criteria should be applied to adults.

(3) The ADHD treatments proven most effective are schedule II psychostimulants, which have a certain potential for abuse.⁴

This article summarizes a review of currently accepted practice in primary care for recognizing and treating ADHD in the young adult patient.

Background
Between 1990 and 1998, the number of school-age children diagnosed with ADHD reportedly increased by 700%.⁵ The accompanying increase in use of schedule II stimulants⁶ (primarily methylphenidate and dexamphetamine) aroused some controversy, even though these medications were shown to be effective in reducing the inattentiveness, impulsivity, and hyperactivity associated with ADHD.^7,8

Concerns regarding the indicated medications—possible abuse, associated adverse effects, inconvenience, stigma—prompted many parents of affected children to decline pharmacologic treatment.⁹ Among treated children, a large proportion discontinued their medications because they did not have a response or experienced intolerable adverse effects.^10,11 Still others were never diagnosed. As a result, a significant number of adolescents with untreated or undertreated ADHD are now entering adulthood. Without treatment now, perhaps half of them will experience lifelong impairment resulting from ADHD and associated comorbidities (ie, conduct and oppositional-defiant disorder, antisocial personality disorder, substance abuse disorder, anxiety disorders, and depression).^1,2,9,10,12

ADHD is believed to have a solid neurobiologic basis, but the condition has no known objective markers. Its diagnosis remains subjective and clinical, depending primarily on structured interviews conducted by trained practitioners.¹³ Unlike most behavioral disorders, which are first understood in adults, then extrapolated to children,¹⁴ ADHD has been recognized and treated in children since the late 1930s¹⁵ but has only recently been identified among significant numbers of adults.¹ Thus, ADHD is currently best understood in children.¹⁴

The classic symptoms and signs of ADHD and its subtypes undergo subtle alterations as the patient matures.^2,12,16 Hyperactivity wanes in adolescence and may be replaced by a restlessness that prompts the adult patient to change jobs and/or living quarters frequently, leading to an unstable lifestyle.¹² Although impulsivity and inattention may persist through adolescence into adulthood, they are often obscured by both coping mechanisms (eg, choice of employment, conscious efforts by high achievers to overcome their disorganization)1 and behavioral comorbidities (depression, self-medication/substance abuse, personality disorders) that the patient may have developed.^10,16 These developments may significantly complicate identification of the disorder in older patients.^2,12,10,16

The adult with ADHD often exhibits low self-esteem, anxiety, depression, sleep disturbances,¹⁷ difficulties with personal relationships and jobs, and impulsivity, which can lead to trouble with the law.¹⁸ The costs to adult ADHD patients, their families, and the community are enormous, making it all the more important for health care professionals to understand this condition.

Diagnostic Criteria
The diagnosis of ADHD is based on criteria from the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition^7,19(DSM-IV; see www.cdc gov/ncbddd/adhd/symptom.htm). ADHD may be widely acknowledged to affect adults, but only recently has an attempt been made to modify the DSM-IV criteria to accommodate the adult patient; changes so far have been limited to minor rewording. As the DSM-IV undergoes significant change at a conservative pace, individual practitioners must decide how best to apply the current criteria to adult patients.

Modifying the DSM-IV Criteria
Adult ADHD is a relatively new diagnostic category. Creating such categories to account for the symptoms of less impaired patients incurs the risk of ascribing pathology to conditions that lie at the margins of normality; hence the reluctance of DSM-IV editors to engage in rapid change. Weighed against their conservative approach, however, is the opportunity to treat individuals whose lives would benefit as a result. Thus, the editors of DSM-IV encourage its use as a guideline rather than a “cookbook.”²⁰ The further practitioners move away from the comorbidities of mental health toward the merging of “soft” morbidity with normality, the more flexibility is required in applying the DSM-IV criteria.

For example, for a diagnosis of adult ADHD, one DSM-IV requirement is for the patient to have experienced onset of symptoms by age 7 (perhaps to distinguish it from confounding comorbidities that develop during or after adolescence). This seems unnecessarily restrictive and can be difficult to establish retrospectively. Even careful history-taking can be insufficient, as third-party observers are likely to be unavailable.^9,13 Although recent studies have shown adult self-determined questionnaires to be an effective means of detecting ADHD impairment during childhood, many practitioners continue to question their validity.²¹ Proposals have been made to modify this age requirement, but agreement has not been reached on a new cutoff point (if one should be specified at all).

Because many “subthreshold” patients might benefit from pharmacotherapy, it has been suggested that the currently required number of DSM-IV criteria (six) should be relaxed. But what should that number be? Requiring only three criteria, researchers recently found, would result in 25% of all presenting patients qualifying for a diagnosis of ADHD.²² Most experts agree that a corresponding increase in psychostimulant use would be unjustified.

The willingness of practitioners to use the current DSM-IV criteria flexibly (eg, deciding what comprises a “clinically significant impairment”) will be determined by their level of comfort in diagnosing DSM-IV–defined disorders. Until continued research can provide more definitive diagnostic criteria for the adult with ADHD, a conservative approach may be advisable to avoid medicating patients unnecessarily.

Supplemental Rating Scales
Experts have developed several rating scales which, while not diagnostic, are nonetheless useful in identifying the adult who is impaired by ADHD but who may not strictly meet the DSM-IV criteria. These include:

• Wender Utah Rating Scale for Adult ADHD.^23,24 One of the earliest and still most useful adjunctive rating scales for adult ADHD,²³ this tool was originally developed to retrospectively identify childhood onset (before age 7) of ADHD symptoms. The original 61 items have been condensed and reorganized into a 25-item self-assessment questionnaire (see Table 1^23,24). The currently used Wender Utah scale seeks to elicit from the adult patient the core symptoms of ADHD.²⁵

• Conners’ Adult ADHD Rating Scales (CAARS).²⁶ This proprietary, 93-question, structured clinical interview allows the clinician to determine the presence of DSM-IV–defined symptoms of ADHD.²⁷ Questions are grouped into nine symptom domains thought to encompass ADHD in adults, with responses categorized into four distinct problem areas²¹ (see Table 2^21,26,27). Although problematic responses appear to correlate highly with confirmed ADHD, a 15% misdiagnosis rate prevents use of the CAARS for definitive diagnosis.²¹

• Brown ADHD Rating Scale for Adults.²⁸ This tool identifies five important symptom clusters (see Table 3^21,28). The Brown scale overlooks hyperactivity in adults and instead emphasizes executive functioning.

• Adult ADHD Self-Report Scale (ASRS-v1.1).²⁹ This self-administered questionnaire, developed through the World Health Organization, assesses for 18 DSM-IV–designated ADHD symptoms, with the first six items found most predictive. If four of these six items are “scored” (ie, the patient responds “Often” or “Very often”), the assessment is considered highly consistent with adult ADHD, and further investigation is warranted. (For seven of the 18 items, an answer of “Sometimes” is also scored. See Table 4.²⁹) Items 7 through 18 provide additional cues to distinguish specific symptoms or impairments.

No consensus exists regarding the reliable use of these rating scales to assist in the diagnosis of adult ADHD. As mentioned earlier, the role of patient self-reported symptoms of ADHD is subject to lingering controversy.²⁷

ADHD Subtypes
Many practitioners find it aids diagnosis to divide ADHD into the subtypes shown in Table 5^19,27; subtypes 4 and 5 are often applicable in this patient population. According to Robison et al,³⁰ however, women with ADHD are more likely to have the combined type (subtype 3) than men are (75% vs 62%, respectively), have a more complex presentation, and display greater impairment than men on all measures of ADHD symptoms.

Promise of Biomarkers
The neurobiologic basis of ADHD is poorly understood. Since medications known to have beneficial effects in ADHD alter dopamine levels,³¹ one prominent theory attributes the condition to dysfunction of dopamine neurotransmission and subsequent disruption of dopamine-modulated circuits among the frontal, striatal, and limbic regions of the brain.³² Early imaging studies using radioligands have shown a 70% increase in levels of the dopamine transporter molecule among subjects with ADHD, compared with non-ADHD controls.³³ Subsequently, however, dopamine levels have been found to vary among subregions of the brain, suggesting that the explanation is probably more complex.^32-34

ADHD medications also alter regulation of norepinephrine and possibly serotonin.³¹ The interplay in the brain between norepinephrine and dopamine is complex, and investigation of these processes is hampered by the current lack of a suitable radioligand that will bind selectively to the norepinephrine transporter molecule.³⁵ Until an objective marker for ADHD is identified, the diagnosis of ADHD remains subjective and purely clinical.  

Treatment
Current treatment recommendations for adult ADHD are almost exclusively pharmacologic. Effective, FDA-approved agents are methylphenidate, dextroamphetamine, and the nonstimulant atomoxetine. Treatment efficacy is determined by patient response, which is far from uniform or predictable. Selecting the optimal drug and dosage for each patient can be a lengthy process. Off-label use of other pharmacologic agents (eg, bupropion, clonidine, modafinil, and the tricyclic antidepressants³¹), combinations of agents, and medication for the ADHD patient with a history of substance abuse are treatments that are best left to a specialist.

Until recently, the role of behavioral therapy for children with ADHD had been somewhat discounted.³⁶ In current research, behavioral therapy appears to help properly motivated adult patients understand their condition and develop appropriate coping skills.³⁷ Self-referred adults with ADHD are usually motivated and compliant with prescribed treatment regimens.³

Currently, few therapeutic options are available for the ADHD-impaired adult who does not meet DSM-IV criteria for stimulant medications. If adults with confirmed ADHD benefit from behavioral therapies, however, their use to treat less impaired, subthreshold ADHD adults (for whom pharmacotherapy may not be warranted) is an intriguing possibility.

Conclusion
Previously considered a childhood-only disorder, ADHD is now known to persist into adulthood in many cases, often causing significant impairment in affected individuals. Ongoing research and brain imaging studies continue to improve our understanding of the neurobiologic basis for ADHD. Since no biomarker has yet been proved valid, diagnosis of ADHD remains subjective and clinical.

No consensus exists regarding the best diagnostic tools for ADHD in the young adult. Applying the DSM-IV criteria for ADHD to the adult patient is controversial. Until more objective data make it possible to modify these criteria, the primary care practitioner must rely on supplemental rating scales and other tools to gather diagnostic information.

Currently, schedule II stimulants and the FDA-approved nonstimulant atomoxetine are the most effective agents known for the adult patient with ADHD. Off-label medication use, combinations of medications, and the addition of behavioral therapy are best handled by a specialist.    

Attention-deficit/hyperactivity disorder (ADHD) was once thought to be limited to overactive or inattentive children. Yet recent studies have shown that ADHD has a 50% to 60% persistence rate into adulthood and may affect as many as seven million adults in the United States today, impairing the ability of many to function productively.^1,2 A significant number of adolescents previously diagnosed with ADHD but not currently receiving treatment are emerging into young adulthood. Some patients are prompted to seek help when their ADHD symptoms interfere with daily functioning; in others, ADHD is identified when they seek treatment for other conditions.

Most older ADHD patients initially present in the primary care setting,³ where practitioners may be reluctant to treat them because:

(1) The diagnosis of ADHD is subjective and purely clinical.

(2) It is unclear how the presently published diagnostic criteria should be applied to adults.

(3) The ADHD treatments proven most effective are schedule II psychostimulants, which have a certain potential for abuse.⁴

This article summarizes a review of currently accepted practice in primary care for recognizing and treating ADHD in the young adult patient.

Background
Between 1990 and 1998, the number of school-age children diagnosed with ADHD reportedly increased by 700%.⁵ The accompanying increase in use of schedule II stimulants⁶ (primarily methylphenidate and dexamphetamine) aroused some controversy, even though these medications were shown to be effective in reducing the inattentiveness, impulsivity, and hyperactivity associated with ADHD.^7,8

Concerns regarding the indicated medications—possible abuse, associated adverse effects, inconvenience, stigma—prompted many parents of affected children to decline pharmacologic treatment.⁹ Among treated children, a large proportion discontinued their medications because they did not have a response or experienced intolerable adverse effects.^10,11 Still others were never diagnosed. As a result, a significant number of adolescents with untreated or undertreated ADHD are now entering adulthood. Without treatment now, perhaps half of them will experience lifelong impairment resulting from ADHD and associated comorbidities (ie, conduct and oppositional-defiant disorder, antisocial personality disorder, substance abuse disorder, anxiety disorders, and depression).^1,2,9,10,12

ADHD is believed to have a solid neurobiologic basis, but the condition has no known objective markers. Its diagnosis remains subjective and clinical, depending primarily on structured interviews conducted by trained practitioners.¹³ Unlike most behavioral disorders, which are first understood in adults, then extrapolated to children,¹⁴ ADHD has been recognized and treated in children since the late 1930s¹⁵ but has only recently been identified among significant numbers of adults.¹ Thus, ADHD is currently best understood in children.¹⁴

The classic symptoms and signs of ADHD and its subtypes undergo subtle alterations as the patient matures.^2,12,16 Hyperactivity wanes in adolescence and may be replaced by a restlessness that prompts the adult patient to change jobs and/or living quarters frequently, leading to an unstable lifestyle.¹² Although impulsivity and inattention may persist through adolescence into adulthood, they are often obscured by both coping mechanisms (eg, choice of employment, conscious efforts by high achievers to overcome their disorganization)1 and behavioral comorbidities (depression, self-medication/substance abuse, personality disorders) that the patient may have developed.^10,16 These developments may significantly complicate identification of the disorder in older patients.^2,12,10,16

The adult with ADHD often exhibits low self-esteem, anxiety, depression, sleep disturbances,¹⁷ difficulties with personal relationships and jobs, and impulsivity, which can lead to trouble with the law.¹⁸ The costs to adult ADHD patients, their families, and the community are enormous, making it all the more important for health care professionals to understand this condition.

Diagnostic Criteria
The diagnosis of ADHD is based on criteria from the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition^7,19(DSM-IV; see www.cdc gov/ncbddd/adhd/symptom.htm). ADHD may be widely acknowledged to affect adults, but only recently has an attempt been made to modify the DSM-IV criteria to accommodate the adult patient; changes so far have been limited to minor rewording. As the DSM-IV undergoes significant change at a conservative pace, individual practitioners must decide how best to apply the current criteria to adult patients.

Modifying the DSM-IV Criteria
Adult ADHD is a relatively new diagnostic category. Creating such categories to account for the symptoms of less impaired patients incurs the risk of ascribing pathology to conditions that lie at the margins of normality; hence the reluctance of DSM-IV editors to engage in rapid change. Weighed against their conservative approach, however, is the opportunity to treat individuals whose lives would benefit as a result. Thus, the editors of DSM-IV encourage its use as a guideline rather than a “cookbook.”²⁰ The further practitioners move away from the comorbidities of mental health toward the merging of “soft” morbidity with normality, the more flexibility is required in applying the DSM-IV criteria.

For example, for a diagnosis of adult ADHD, one DSM-IV requirement is for the patient to have experienced onset of symptoms by age 7 (perhaps to distinguish it from confounding comorbidities that develop during or after adolescence). This seems unnecessarily restrictive and can be difficult to establish retrospectively. Even careful history-taking can be insufficient, as third-party observers are likely to be unavailable.^9,13 Although recent studies have shown adult self-determined questionnaires to be an effective means of detecting ADHD impairment during childhood, many practitioners continue to question their validity.²¹ Proposals have been made to modify this age requirement, but agreement has not been reached on a new cutoff point (if one should be specified at all).

Because many “subthreshold” patients might benefit from pharmacotherapy, it has been suggested that the currently required number of DSM-IV criteria (six) should be relaxed. But what should that number be? Requiring only three criteria, researchers recently found, would result in 25% of all presenting patients qualifying for a diagnosis of ADHD.²² Most experts agree that a corresponding increase in psychostimulant use would be unjustified.

The willingness of practitioners to use the current DSM-IV criteria flexibly (eg, deciding what comprises a “clinically significant impairment”) will be determined by their level of comfort in diagnosing DSM-IV–defined disorders. Until continued research can provide more definitive diagnostic criteria for the adult with ADHD, a conservative approach may be advisable to avoid medicating patients unnecessarily.

Supplemental Rating Scales
Experts have developed several rating scales which, while not diagnostic, are nonetheless useful in identifying the adult who is impaired by ADHD but who may not strictly meet the DSM-IV criteria. These include:

• Wender Utah Rating Scale for Adult ADHD.^23,24 One of the earliest and still most useful adjunctive rating scales for adult ADHD,²³ this tool was originally developed to retrospectively identify childhood onset (before age 7) of ADHD symptoms. The original 61 items have been condensed and reorganized into a 25-item self-assessment questionnaire (see Table 1^23,24). The currently used Wender Utah scale seeks to elicit from the adult patient the core symptoms of ADHD.²⁵

• Conners’ Adult ADHD Rating Scales (CAARS).²⁶ This proprietary, 93-question, structured clinical interview allows the clinician to determine the presence of DSM-IV–defined symptoms of ADHD.²⁷ Questions are grouped into nine symptom domains thought to encompass ADHD in adults, with responses categorized into four distinct problem areas²¹ (see Table 2^21,26,27). Although problematic responses appear to correlate highly with confirmed ADHD, a 15% misdiagnosis rate prevents use of the CAARS for definitive diagnosis.²¹

• Brown ADHD Rating Scale for Adults.²⁸ This tool identifies five important symptom clusters (see Table 3^21,28). The Brown scale overlooks hyperactivity in adults and instead emphasizes executive functioning.

• Adult ADHD Self-Report Scale (ASRS-v1.1).²⁹ This self-administered questionnaire, developed through the World Health Organization, assesses for 18 DSM-IV–designated ADHD symptoms, with the first six items found most predictive. If four of these six items are “scored” (ie, the patient responds “Often” or “Very often”), the assessment is considered highly consistent with adult ADHD, and further investigation is warranted. (For seven of the 18 items, an answer of “Sometimes” is also scored. See Table 4.²⁹) Items 7 through 18 provide additional cues to distinguish specific symptoms or impairments.

No consensus exists regarding the reliable use of these rating scales to assist in the diagnosis of adult ADHD. As mentioned earlier, the role of patient self-reported symptoms of ADHD is subject to lingering controversy.²⁷

ADHD Subtypes
Many practitioners find it aids diagnosis to divide ADHD into the subtypes shown in Table 5^19,27; subtypes 4 and 5 are often applicable in this patient population. According to Robison et al,³⁰ however, women with ADHD are more likely to have the combined type (subtype 3) than men are (75% vs 62%, respectively), have a more complex presentation, and display greater impairment than men on all measures of ADHD symptoms.

Promise of Biomarkers
The neurobiologic basis of ADHD is poorly understood. Since medications known to have beneficial effects in ADHD alter dopamine levels,³¹ one prominent theory attributes the condition to dysfunction of dopamine neurotransmission and subsequent disruption of dopamine-modulated circuits among the frontal, striatal, and limbic regions of the brain.³² Early imaging studies using radioligands have shown a 70% increase in levels of the dopamine transporter molecule among subjects with ADHD, compared with non-ADHD controls.³³ Subsequently, however, dopamine levels have been found to vary among subregions of the brain, suggesting that the explanation is probably more complex.^32-34

ADHD medications also alter regulation of norepinephrine and possibly serotonin.³¹ The interplay in the brain between norepinephrine and dopamine is complex, and investigation of these processes is hampered by the current lack of a suitable radioligand that will bind selectively to the norepinephrine transporter molecule.³⁵ Until an objective marker for ADHD is identified, the diagnosis of ADHD remains subjective and purely clinical.  

Treatment
Current treatment recommendations for adult ADHD are almost exclusively pharmacologic. Effective, FDA-approved agents are methylphenidate, dextroamphetamine, and the nonstimulant atomoxetine. Treatment efficacy is determined by patient response, which is far from uniform or predictable. Selecting the optimal drug and dosage for each patient can be a lengthy process. Off-label use of other pharmacologic agents (eg, bupropion, clonidine, modafinil, and the tricyclic antidepressants³¹), combinations of agents, and medication for the ADHD patient with a history of substance abuse are treatments that are best left to a specialist.

Until recently, the role of behavioral therapy for children with ADHD had been somewhat discounted.³⁶ In current research, behavioral therapy appears to help properly motivated adult patients understand their condition and develop appropriate coping skills.³⁷ Self-referred adults with ADHD are usually motivated and compliant with prescribed treatment regimens.³

Currently, few therapeutic options are available for the ADHD-impaired adult who does not meet DSM-IV criteria for stimulant medications. If adults with confirmed ADHD benefit from behavioral therapies, however, their use to treat less impaired, subthreshold ADHD adults (for whom pharmacotherapy may not be warranted) is an intriguing possibility.

Conclusion
Previously considered a childhood-only disorder, ADHD is now known to persist into adulthood in many cases, often causing significant impairment in affected individuals. Ongoing research and brain imaging studies continue to improve our understanding of the neurobiologic basis for ADHD. Since no biomarker has yet been proved valid, diagnosis of ADHD remains subjective and clinical.

No consensus exists regarding the best diagnostic tools for ADHD in the young adult. Applying the DSM-IV criteria for ADHD to the adult patient is controversial. Until more objective data make it possible to modify these criteria, the primary care practitioner must rely on supplemental rating scales and other tools to gather diagnostic information.

Currently, schedule II stimulants and the FDA-approved nonstimulant atomoxetine are the most effective agents known for the adult patient with ADHD. Off-label medication use, combinations of medications, and the addition of behavioral therapy are best handled by a specialist.