Nathalie V. Buitrago, PsyD

The prevalence of attention-deficit/hyperactivity disorder (

) in the worldwide pediatric population has been stable over the past 30 years except in the United States, where cases have increased.

 According to a 2016 parent survey, approximately 6.1 million US children (9.4%) had received a diagnosis of ADHD.

 Worldwide, ADHD is the third most common mental health disorder, following depression and anxiety.

 Overall, girls (5.6%) are less likely to be diagnosed with ADHD than boys (12.9%).

A 2021 global systematic review and meta-analysis suggested that the prevalence of persistent adult ADHD was 2.58% and the prevalence of symptomatic adult ADHD was 6.76%, with 139.84 million and 366.33 million affected adults worldwide in 2020, respectively.

 ADHD appears to impact men more than women. In adults, ADHD appears to decrease as an individual ages.

Etiology is still not clearly understood; however, combinations of genetic, neurological, and environmental factors likely contribute to its pathogenesis and symptom expression.

 Genetic factors are implicated, but the mechanism of action is not completely clear. Family, twin, and adoption studies have strongly suggested that ADHD is highly inheritable. Moreover, genetic studies have documented the gene sets interfering with neurotransmitter pathways in the brain that implicate rare copy number variants or the collection of higher deletions, as well as the duplications impacting gene transcriptions that are more likely to be found in individuals with ADHD.

Pre-, peri-, and postnatal environmental factors play a significant role in the development of ADHD. Some evidence suggests prenatal factors include the mother’s lifestyle during pregnancy.

 For example, prenatal alcohol exposure can lead to hyperactive, disruptive, and impulsive behaviors and increase the risk of psychiatric disorders.

 Maternal smoking during the prenatal developmental period has been linked to increased risk of ADHD

 Perinatal factors, such as very low birthweight, can result in a 2-fold increase in the likelihood of ADHD.

ADHD is conceptualized as a disorder of childhood that gradually diminishes over the lifespan.

 However, several prospective longitudinal studies have challenged the prevailing assumption that childhood ADHD and adult ADHD affect the same individuals, and that they share the same neurodevelopmental vulnerabilities.

 The results of these studies suggest that more than two-thirds of individuals with adult ADHD never had childhood ADHD. Adult ADHD had been generally neglected in epidemiological studies, until recently, as researchers attempt to estimate the true prevalence of ADHD in adults. Furthermore, researchers are exploring whether ADHD is solely a neurodevelopmental disorder that presents in childhood, or whether ADHD can be acquired during other developmental periods. The prevalence of persistent adult ADHD from childhood and that of symptomatic adult ADHD were 2.58% and 6.76% in 2020, respectively.

The diagnostic assessment of ADHD can be complicated, as inattention, impulsivity, and difficulties with concentration can be driven by myriad factors. It is well documented that children and adolescents diagnosed with ADHD often have 1 or more cooccurring disorders

Co-Occurring Disorders in Children and Adolescents Diagnosed with ADHD

According to a study by Elia and colleagues, oppositional defiance disorder was the most common comorbid disorder at 41%, followed by depression/dysthymia at 22% and general anxiety disorder at 15%.

Approximately 60% to 100% of children with ADHD have 1 or more comorbid disorders that persist into adulthood. Autism spectrum disorder, with a comorbid rate of 42%, and learning disorders (math, reading, and spelling), account for 10% and 92% of comorbidities. Tourette syndrome accounts for 55% comorbidity. Children with ADHD experience major depression at a rate higher than children without ADHD (12% to 50%). Regarding anxiety symptoms, children with ADHD have a prevalence rate between 15% and 35%.

In adults with ADHD, the most common cooccurring psychiatric disorders are bipolar disorder, depression, anxiety disorders, substance use disorders (SUDs), and personality disorders.

 ADHD has a high cooccurring prevalence with bipolar disorder: Estimates range between 9.5% and 21.2%, with bipolar I disorder being more likely.

 ADHD and depression commonly cooccur at even higher rates, ranging from 18.6% to 53.3%.

 Individuals with ADHD are also at higher risk for developing anxiety disorders than the general population, with rates approaching 50%.

 SUDs are likely the most common cooccurring condition with ADHD—specifically, alcohol and/or nicotine, cannabis, and cocaine use.

Research support for the intersection of ADHD and personality disorders is scant compared with the support of other psychiatric cooccurring conditions. However, reports indicate that personality pathology is present in approximately 50% of adults with ADHD—most commonly cluster B and C personality structures—and up to 25% of adults with ADHD have 2 or more personality conditions.

Diagnosing ADHD can be a complicated process. It is imperative to obtain historical information such as academic performance records and previous psychological testing reports, if ever tested.

There are several significant barriers to diagnosis and treatment in ADHD, including overlapping symptomology between ADHD and mood and anxiety disorders, SUDs, learning disabilities, information processing disorders, auditory processing disorders, and psychosocial factors. It is important to note that some individuals overcome ADHD-related deficits by developing and mastering compensating skills. This also can impact the accuracy of ADHD diagnosis.

Evidenced-based assessment includes multi-informant/multimethod procedures and validated measures. This approach should be guided by current research and include test data to support clinical observations and, ultimately, an accurate ADHD diagnosis. 

 highlights several measures used in ADHD assessments.

Treatment considerations should be informed by functional outcomes including symptom reduction, increased quality of life, and improved daily, academic, and occupational functioning.

 Efficiency at working or studying, maintaining stable relationships, containing or curbing impulsivity, and being satisfied with life overall are indicators of improved functioning. Moreover, adherence to treatment is key to successful management of ADHD.

First-line treatments for ADHD are pharmacologic: stimulants and nonstimulants. Stimulant medications include methylphenidate, mixed amphetamine salts, and lisdexamfetamine dimesylate. Nonstimulants used in ADHD treatment include atomoxetine and alpha-2-adrenergic agonists. 

 highlights several ADHD medication options, although the effectiveness of psychopharmacological treatments is beyond the scope of this paper.

For children and adolescents, a well-established body of evidence supports the effectiveness of psychosocial treatments, including behavioral management interventions (eg, parent training, classroom interventions, peer-based interventions), training interventions (eg, cognitive training, neurofeedback, organization), cognitive behavioral therapy (CBT), and physiological treatments (eg, play and other physical activities).

CBT, the preferred nonpharmacological treatment for adult ADHD, consistently reduces its core behavioral symptoms.

Usually first diagnosed in childhood and sometimes persisting into adulthood, ADHD has extensive implications for academic achievement, relationships, finances, and employment. In addition, untreated ADHD carries greater risk of accidental injuries and substance abuse. Thus, careful assessment is of utmost importance to properly diagnose and then treat the disorder.

is an assistant professor and licensed clinical psychologist at Harris Health System in the Menninger Department of Psychiatry and Behavioral Sciences at Baylor College of Medicine in Houston, Texas. 

 is a psychology fellow at Baylor College of Medicine.

1. Polanczyk GV, Willcutt EG, Salum GA, et al. 

ADHD prevalence estimates across three decades: an updated systematic review and meta-regression analysis

2. Danielson ML, Bitsko RH, Ghandour RM, et al. 

Prevalence of parent-reported ADHD diagnosis and associated treatment among U.S. children and adolescents, 2016

3. Bélanger SA, Andrews D, Gray C, Korczak D. 

ADHD in children and youth: part 1 - etiology, diagnosis, and comorbidity

The prevalence of adult attention-deficit hyperactivity disorder: a global systematic review and meta-analysis

Molecular genetics of attention deficit hyperactivity disorder

6. Stergiakouli E, Hamshere M, Holmans P, et al; deCODE Genetics; Psychiatric GWAS Consortium. 

Investigating the contribution of common genetic variants to the risk and pathogenesis of ADHD

7. Williams NM, Franke B, Mick E, et al. 

Genome-wide analysis of copy number variants in attention deficit hyperactivity disorder: the role of rare variants and duplications at 15q13.3

9. D’Onofrio BM, Van Hulle CA, Waldman ID, et al. 

Causal inferences regarding prenatal alcohol exposure and childhood externalizing problems

Maternal prenatal substance use and behavior problems among children in the U.S.

11. Milberger S, Biederman J, Faraone SV, Chen L, Jones J. 

Is maternal smoking during pregnancy a risk factor for attention deficit hyperactivity disorder in children?

12. Kotimaa AJ, Moilanen I, Taanila A, et al. 

Maternal smoking and hyperactivity in 8-year-old children

Practitioner review: early adversity and developmental disorders

14. Moffitt TE, Houts R, Asherson P, et al. 

Is adult ADHD a childhood-onset neurodevelopmental disorder? evidence from a four-decade longitudinal cohort study

15. Agnew-Blais JC, Polanczyk GV, Danese A, et al. 

Evaluation of the persistence, remission, and emergence of attention-deficit/hyperactivity disorder in young adulthood

16. Caye A, Botter-Maio Rocha T, Anselmi L, et al. 

Attention-deficit/hyperactivity disorder trajectories from childhood to young adulthood: evidence from a birth cohort supporting a late-onset syndrome

. 2005;366(9481):237-248. Published correction appears in 

18. Larson K, Russ SA, Kahn RS, Halfon N. 

Patterns of comorbidity, functioning, and service use for US children with ADHD, 2007

19. Elia J, Ambrosini P, Berrettini W. ADHD characteristics: I. 

Concurrent co-morbidity patterns in children & adolescents

20. Gnanavel S, Sharma P, Kaushal P, Hussain S. 

Attention deficit hyperactivity disorder and comorbidity: a review of literature

21. Katzman MA, Bilkey TS, Chokka PR, et al. 

Adult ADHD and comorbid disorders: clinical implications of a dimensional approach

A systematic review of rates and diagnostic validity of comorbid adult attention-deficit/hyperactivity disorder and bipolar disorder

23. Torgersen T, Gjervan B, Rasmussen K. 

ADHD in adults: a study of clinical characteristics, impairment and comorbidity

24. Mancini C, Van Ameringen M, Oakman JM, Figueiredo D. 

Childhood attention deficit/hyperactivity disorder in adults with anxiety disorders

25. Braaten EB, Beiderman J, Monuteaux MC, et al. 

Revisiting the association between attention-deficit/hyperactivity disorder and anxiety disorders: a familial risk analysis

26. Kessler RC, Adler L, Barkley R, et al. 

The prevalence and correlates of adult ADHD in the United States: results from the National Comorbidity Survey Replication

27. Klassen LJ, Bilkey TS, Katzman MA, Chokka P. 

Comorbid attention deficit/hyperactivity disorder and substance use disorder: treatment considerations

28. Olsen JL, Reimherr FW, Marchant BK, et al. 

The effect of personality disorder symptoms on response to treatment with methylphenidate transdermal system in adults with attention-deficit/hyperactivity disorder

29. Rösler M, Ginsberg Y, Arngrim T, et al. 

Correlation of symptomatic improvements with functional improvements and patient-reported outcomes in adults with attention-deficit/hyperactivity disorder treated with OROS methylphenidate

30. Shrestha M, Lautenschleger J, Soares N. 

Non-pharmacologic management of attention-deficit/hyperactivity disorder in children and adolescents: a review

31. Pliszka S; AACAP Work Group on Quality Issues. 

Practice parameter for the assessment and treatment of children and adolescents with attention-deficit/hyperactivity disorder

Evidence-based psychosocial treatments for children and adolescents with attention-deficit/hyperactivity disorder

Behavior management for school-aged children with ADHD

34. Nimmo-Smith V, Merwood A, Hank D, et al. 

Non-pharmacological interventions for adult ADHD: a systematic review

Articles

Is it ADHD—or something else? The importance of careful assessment for the proper diagnosis and effective treatment of the third most common mental health disorder worldwide.

ADHD Update: Diagnosis, Assessment, and Treatment Issues

Attention-deficit/hyperactivity disorder (

) is one of the most common neurodevelopmental disorders of childhood.

 This disorder is typically first diagnosed in childhood and can persist into adulthood, with far-reaching implications on academic achievement, employment, finances, peer relationships, and increased accidental injuries and substance abuse.

 Children with ADHD may have difficulty initiating and maintaining attention, concentrating, completing tasks, and controlling impulsive behaviors. According to the American Psychiatric Association, there are 3 types of ADHD: predominantly inattentive presentation; predominantly hyperactive-impulsive presentation, and combined presentation.

ADHD prevalence in the pediatric population has been stable over the past 30 years except in the United States, where cases have increased.

 According to a 2016 parent survey, approximately 6.1 million (9.4%) children received a diagnosis of ADHD in the United States.

 Overall, girls are less likely to be diagnosed with ADHD than boys.

 A 2021 global systematic review and meta-analysis suggested that the prevalence of persistent adult ADHD was 2.58%, and the prevalence of symptomatic adult ADHD was 6.76%, with 139.84 million and 366.33 million affected adults worldwide in 2020, respectively.

 ADHD appears to impact men more than women. In adults, ADHD decreases as an individual ages.

The etiology of ADHD is still not clearly understood; however, combinations of genetic, neurological, and environmental factors contribute to the pathogenesis and symptom expression.

 Genetic factors are implicated in ADHD, but the mechanism of action is not completely clear. Family, twin, and adoption studies have strongly suggested that ADHD is highly inheritable. Moreover, genetic studies have documented the gene sets interfering with neurotransmitter pathways in the brain that implicate rare copy number variants or the collection of higher deletions, as well as the duplications impacting gene transcriptions that are more likely to be found in individuals with ADHD.

Pre-, peri-, and postnatal environmental factors play a significant role in the development of ADHD. Prenatal factors include the mother’s lifestyle during pregnancy.

 Perinatal factors such as very low-birthweight children have a twofold increase in ADHD.

 However, several prospective longitudinal studies have challenged the prevailing assumption that childhood ADHD and adult ADHD affect the same individuals who share the same neurodevelopmental vulnerabilities.

 These studies suggest that more than two-thirds of individuals with adult ADHD never had childhood ADHD. Adult ADHD is generally neglected in epidemiological studies, and, until recently, many attempts have been made to estimate the prevalence of ADHD in adults. Further, researchers are exploring whether ADHD is solely a neurodevelopmental disorder that is diagnosed in childhood, or whether ADHD can be acquired during other developmental periods. The prevalence of persistent adult ADHD from childhood and that of symptomatic adult ADHD were 2.58% and 6.76% in 2020, respectively.

The diagnostic assessment of ADHD can be complicated, as inattention, impulsivity, and difficulties with concentration can be driven by a myriad of factors. It is well-documented that children and adolescents diagnosed with ADHD have a cooccurring disorder.

 It is estimated that 45% children and adolescents with ADHD have a learning disability; 27% have a conduct disorder diagnosis; 18% have an anxiety disorder; and 15% have a depressive disorder.

 According to a study by Elia and colleagues, oppositional defiance disorder was the most common comorbid disorder at 41%, followed by depression/dysthymia at 22% and general anxiety disorder at 15%.

In adults with ADHD, the most common cooccurring psychiatric disorders are depression, anxiety disorders, bipolar disorder, substance use disorders (SUDs), and personality disorders.

 ADHD and depression commonly cooccur at high rates ranging from 18.6% to 53.3%.

 Individuals with ADHD are at higher risk for developing anxiety disorders than the general population with rates approaching 50%.

 SUDS are likely the most common cooccurring condition with ADHD—specifically alcohol and/or nicotine, cannabis, and cocaine use.

Research support for the intersection of ADHD and personality disorders is scant compared to the support of other psychiatric cooccurring conditions. However, reports indicate that personality pathology are present approximately 50% of adults with ADHD—most commonly cluster B and C personality structures—and up to 25% of adults with ADHD have 2 or more personality conditions.

It is important to differentiate if an individual is presenting with any of the above-mentioned conditions to determine if they have comorbid ADHD. Diagnosing ADHD can be a complicated process that goes beyond a checklist. It is imperative to obtain historical information such as academic performance records and previous psychological testing reports, if ever tested. There are several significant barriers to diagnosis and treatment in ADHD, including overlapping symptomology between ADHD and mood, anxiety, SUDS, learning disabilities, information processing disorders, auditory processing disorders, and psychosocial factors. Another key barrier to the accurate diagnosis of ADHD is that some individuals will be able to overcome their deficits by developing and mastering compensating skills that will likely impact the accuracy of ADHD diagnosis and treatment.

Evidenced-based assessment that includes multi-informant/multimethod methods and evidenced-based assessment measures are well-regarded and arguably gold-standard approaches to the assessment of ADHD. This approach should be guided by current research and include test data to support clinical observations and, ultimately, an accurate ADHD diagnosis. 

 highlights several measures used in ADHD assessment conducted by clinical psychologists.

Treatment considerations should be informed by functional outcomes, which include symptom reduction; improved daily, academic, and occupational functioning; and increased quality of life.

The first line of ADHD are pharmacologic treatments, which are divided into stimulants and nonstimulants. Stimulant medications include methylphenidate, mixed amphetamine salts, and lisdexamfetamine dimesylate. Nonstimulants used in ADHD treatment include atomoxetine and alpha-2-adrenergic agonists. 

 highlights several medication options for ADHD.

There is a well-established body of evidence highlighting the effectiveness of psychosocial treatments for ADHD in children and adolescents, which include behavioral management interventions (parent training, classroom interventions, and peer-based interventions), training interventions (cognitive training, neurofeedback, and organization), cognitive behavioral therapy (CBT), and physiological treatments (play and other physical activities).

 CBT is the preferred nonpharmacological treatment for adult ADHD, which shows consistent reduction in the core behavioral symptoms of ADHD.

 is an assistant professor and licensed clinical psychologist at Harris Health System in the Menninger Department of Psychiatry and Behavioral Sciences at Baylor College of Medicine. 

1. Faraone SV, Banaschewski T, Coghill D, et al. 

The World Federation of ADHD international consensus statement: 208 evidence-based conclusions about the disorder

The transition of youth with ADHD into the workforce: review and future directions

3. Polanczyk GV, Willcutt EG, Salum GA, et al. 

4. Danielson ML, Bitsko RH, Ghandour RM, et al. 

5. Bélanger SA, Andrews D, Gray C, Korczak D. 

ADHD in children and youth: part 1-etiology, diagnosis, and comorbidity

8. Stergiakouli E, Hamshere M, Holmans P, et al. 

9. Williams NM, Franke B, Mick E, et al. 

11. D'Onofrio BM, Van Hulle CA, Waldman ID, et al. 

13. Milberger S, Biederman J, Faraone SV, et al. 

14. Kotimaa AJ, Moilanen I, Taanila A, et al. 

16. Moffitt TE, Houts R, Asherson P, et al. 

17. Agnew-Blais JC, Polanczyk GV, Danese A, et al. 

 [published correction appears in Lancet. 2006 Jan 21;367(9506):210]. 

20. Larson K, Russ SA, Kahn RS, Halfon N. 

ADHD characteristics: I. concurrent co-morbidity patterns in children & adolescents

22. Katzman MA, Bilkey TS, Chokka PR, et al. 

24. Torgersen T, Gjervan B, Rasmussen K. 

25. Mancini C, Van Ameringen M, Oakman JM, Figueiredo D. 

26. Braaten EB, Beiderman J, Monuteaux MC, et al. 

27. Kessler RC, Adler L, Barkley R, et al. 

28. Klassen LJ, Bilkey TS, Katzman MA, Chokka P. 

29. Olsen JL, Reimherr FW, Marchant BK, et al. 

30. Rösler M, Ginsberg Y, Arngrim T, et al. 

31. Shrestha M, Lautenschleger J, Soares N. 

32. Pliszka S; AACAP Work Group on Quality Issues. 

35. Nimmo-Smith V, Merwood A, Hank D, et al. 

The importance of understanding diagnosis, assessment, and treatment.

Nathalie V. Buitrago, PsyD

Articles

ADHD Update: Diagnosis, Assessment, and Treatment Issues

ADHD—or Something Else?