Attention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental condition characterized by persistent patterns of inattention, hyperactivity, and impulsivity. These patterns can significantly affect an individual’s functioning in various life areas, including academic performance, work, and relationships. ADHD is recognized as a condition that can affect individuals across their entire lifespan, with symptoms and their impact evolving over time.
Prevalence of ADHD in the Population
In the United States, an estimated 11.4% of children aged 3–17 years have received an ADHD diagnosis, according to a 2022 national survey. Other estimates from the American Psychiatric Association suggest a prevalence of approximately 8.4% among children.
The prevalence in adults varies, with estimates ranging from 2.5% to 6% of the adult population. While the American Psychiatric Association reports around 2.5% of adults have ADHD, other research indicates that approximately 4.4% of adults aged 18 to 44 years experience the condition. A more recent study suggests that up to 6% of U.S. adults have an ADHD diagnosis, with about half receiving their diagnosis during adulthood.
Factors Influencing Diagnosis Rates
Several factors influence ADHD diagnosis rates. Increased public and professional awareness leads more individuals to seek evaluation and more clinicians to recognize symptoms. This heightened recognition extends to previously underdiagnosed groups, such as adults and women.
Changes in diagnostic criteria have also impacted prevalence figures. The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), released in 2013, introduced modifications that broadened the criteria for diagnosis. These changes included extending the age of symptom onset for diagnosis from seven to twelve years and reducing the number of symptoms required for an adult ADHD diagnosis. The DSM-5 also permitted a co-occurring ADHD diagnosis for individuals with autism spectrum disorder.
Debates exist about potential overdiagnosis in some populations versus underdiagnosis in others. While concerns exist regarding overprescription of stimulant medications, there is also evidence of diagnostic disparities, particularly among underrepresented populations and women. The COVID-19 pandemic also contributed to a notable increase in individuals seeking help for ADHD symptoms, further influencing diagnosis trends.
Variations in ADHD Presentation and Demographics
ADHD presentation and distribution differ across demographic groups, particularly by gender and age. In childhood, boys are diagnosed with ADHD more frequently than girls; for instance, boys account for 15% of diagnoses compared to 8% for girls. This disparity is often attributed to differences in symptom manifestation.
Boys tend to exhibit more externalizing symptoms, such as hyperactivity and impulsivity, which are readily observable and often lead to referrals for evaluation. Girls, conversely, may present with more internalizing symptoms like inattention, disorganization, and quiet daydreaming, which can be less disruptive in classroom or home settings and thus overlooked. Consequently, many girls may not receive a diagnosis until later in adolescence or adulthood.
As individuals with ADHD transition from childhood to adulthood, symptom manifestation can also change. Overt hyperactivity, such as excessive physical movement, often diminishes with age. However, internal restlessness and difficulties with executive functions, including challenges with attention, organization, and impulse control, frequently persist into adult life. These enduring challenges can significantly affect daily functioning in educational, professional, and personal spheres.
The Frequency of Co-occurring Conditions
ADHD frequently co-exists with other mental health, neurodevelopmental, and learning conditions, a phenomenon known as comorbidity. This often complicates diagnosis and treatment, as many individuals experience at least one other co-occurring disorder.
Among children and adolescents with ADHD, common co-occurring conditions include Oppositional Defiant Disorder (ODD), present in around 41% of cases. Minor depression or dysthymia affects approximately 22% of children with ADHD, and generalized anxiety disorder is seen in about 15%. Learning disabilities, such as dyslexia or dyscalculia, are also common, affecting between 31% and 45% of children with ADHD.
In adults with ADHD, rates of co-occurring conditions are substantial, with up to 89% having at least one additional psychiatric diagnosis during their lifetime. Anxiety disorders are particularly prevalent, affecting nearly half of adults with ADHD, while mood disorders, including major depressive disorder and bipolar disorder, are also frequently observed. Substance use disorders are another common comorbidity, occurring in a notable percentage of individuals with ADHD.
Brainwave Frequencies and ADHD
Research has investigated brainwave activity in individuals with ADHD, focusing on the ratio of theta waves to beta waves. Theta waves are associated with drowsiness or relaxed wakefulness, while beta waves are linked to alert, active thinking.
Studies report that individuals with ADHD often exhibit an increased theta/beta ratio, meaning they have more slower theta wave activity compared to faster beta wave activity. This pattern has been described as one of the most reproducible psychophysiological findings in ADHD research. Quantitative electroencephalography (qEEG) is a tool used to measure these patterns.
While the Food and Drug Administration (FDA) approved the theta/beta ratio as part of the Neuropsychiatric EEG-Based Assessment Aid (NEBA) system for ADHD diagnosis in 2013, it is not a standalone diagnostic method. Its diagnostic accuracy has yielded mixed results, with some studies suggesting high sensitivity and specificity, while others indicate a risk of false-positive diagnoses. Experts advise that relying solely on the theta/beta ratio for diagnosis could lead to misdiagnosis and that it should not replace a thorough clinical evaluation. Additionally, some findings suggest that the elevated theta/beta ratio might sometimes reflect slowed alpha peak frequencies rather than a true increase in theta activity.