Understanding the Onset and Prevalence of ADHD

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder, affecting both children and adults around the world. Individuals with ADHD struggle with persistent patterns of inattention (finding it hard to focus) and may also experience hyperactivity, restlessness, and impulsivity.

While everyone might occasionally find it hard to pay attention, people with ADHD struggle to the degree that it affects their quality of life, finding it harder than most to stay organized, meet deadlines, and manage stress.

If you suspect that you or your child might have ADHD, it’s a good idea to make an appointment with your doctor to discuss possible symptoms^[1].

How Prevalent is ADHD?

ADHD is among the most common neurodevelopmental disorders worldwide. Prevalence can vary quite dramatically from country to country, potentially due to varying diagnostic practices among other social and cultural factors.

In the United States, the Centers for Disease Control and Prevention (CDC) estimates that approximately 11.4% of children aged 3 to 17 had been diagnosed with ADHD in 2022^[2]. In 2023, the CDC estimated that 15.5 million U.S. adults—about 6% of the population—had an ADHD diagnosis, with nearly half receiving their diagnosis in adulthood^[3].

Globally, ADHD prevalence averages around 8.0% for children and adolescents and is more common among boys (10%) than girls (5%)^[4]. In 2020, the prevalence of adult ADHD that had persisted was 2.58% (139.84 million), while 6.76% (366.33 million) had symptomatic adult ADHD worldwide^[5].

What is the Typical Age of Onset of ADHD?

ADHD typically begins to present in early childhood, and the vast majority of adults with an ADHD diagnosis recall showing symptoms before turning 12 years old^[6].

However, ADHD age of onset changes from person to person, and symptoms typically vary across different stages of life.

Symptoms for children and adolescents usually include:

• Forgetfulness
• A short attention span
• Struggling to sit still
• Easily distractible
• Fidgeting
• Difficulty following instructions
• Regularly switching tasks
• Impatience
• Talkativeness
• Difficulty staying organized^[7]

In early childhood, symptoms can include:

• Frequent daydreaming
• Squirming and fidgeting
• Difficulty taking turns
• Forgetfulness
• Talkativeness
• Finding it hard to get along with others^[8]

Children tend to internalize criticism and shame, and children with ADHD might struggle with low self-esteem. For this reason, it’s important not to shame children for interrupting, forgetting things, or struggling to complete homework tasks.

Rather, try to keep in mind that children with ADHD cannot help their behavior. Offering gentle reminders, praising specific actions, and patiently repeating instructions when necessary can help them feel capable of getting things right^[9].

For adults to be diagnosed with ADHD, they will need to report past symptoms, as a diagnosis relies on the occurrence of symptoms before age 12^[6].

Symptoms may present somewhat differently as an adult and usually include:

• Difficulty focusing
• Beginning a new task before completing the last one
• Difficulty staying on task and prioritizing tasks
• Disorganization
• Forgetfulness
• Restlessness
• Irritability and mood swings
• Impatience
• Difficulty keeping quiet
• A seeming lack of attention to detail
• Risk-taking and impulsive behaviors^[7]

ADHD Prevalence by Gender

ADHD statistics show that it is more commonly diagnosed and treated in males than females, with a male-to-female ratio of approximately 3:1 in population-based studies of children.

There might be many reasons for these disparities, including that girls express ADHD differently than boys, which may contribute to late or missed diagnoses in females.

In particular, adolescent females tend to internalize symptoms more than their male counterparts, meaning their emotions and experiences are not as often outwardly expressed. Examples of outward expression include hyperactivity and impulsivity.

In adults, ADHD prevalence is similarly higher for males (5.4%) compared to females (3.2%)^[6].

ADHD diagnoses have often relied on evaluations of executive function, though recent studies indicate that many individuals with ADHD reflect normal executive function when tested. Still, there’s a possibility that normally developing boys report lower levels of executive function compared to normally developing girls between 5 and 18 years, which might play a role in masking ADHD in adolescent females^[10].

ADHD Prevalence by Race

Research indicates variability in ADHD prevalence across different racial and ethnic groups.

In a study by the CDC, white children presented higher rates of ADHD diagnoses (13.4%) compared to Black (10.8%) and Hispanic (8.9%) children.

Additionally, children with public or private health insurance were more often diagnosed with ADHD, compared to children without insurance^[11].

Contributing reasons for these disparities are not completely clear, though studies suggest they include:

• Access to healthcare: Accessing quality healthcare is a socio-economic concern, which varies across racial and ethnic groups.
• Cultural values: Because of the variations in ADHD presentations, different cultural values may impact the perceptions of symptomatic behaviors.
• Bias in diagnostic practices: Patients’ and parents’ anxieties and concerns about racism, bias, and discrimination in the healthcare system might cause them to refrain from seeking support, while white individuals are more willing to do so.

Additionally, compared to Black and Hispanic children, white children are more likely to be treated for ADHD^[12].

ADHD Prevalence by Region

In the United States, ADHD prevalence varies across states and regions.

A recent scientific report indicates that the highest percentage of children with ADHD is in Louisiana, at 15.7%. California has a prevalence rate of 5.6%, which is the lowest.

This study indicated correlations between ADHD diagnoses and unsafe school and neighborhood environments, as well as economic hardships.

Excluding Louisiana and Nevada, all states with more urban neighborhood amenities, such as parks and libraries, had fewer cases of ADHD among children^[13].

These findings suggest that children who grow up in supportive, safe, and enriching regions of the United States are less likely to receive an ADHD diagnosis.

Common ADHD Comorbidities

ADHD frequently co-occurs with other conditions, which include but aren’t limited to the following:

• Oppositional defiant disorder (ODD): One of the most common disorders to co-occur with ADHD, ODD causes children to act out and defy rules or instructions. Children with ODD often get angry, throw a tantrum, lose their temper, and physically hurt others. They also struggle to take responsibility for their behavior.
• Conduct disorder (CD): Like those with ODD, individuals with conduct disorder show patterns of aggression and tend not to follow the rules. For children, these behaviors may occur at school or home, increasing their risk of injury. Meanwhile, adults with CD tend to display aggressive behavior and are more prone to encountering legal troubles.
• Learning disorder (LD): In addition to the focus-related symptoms that present in children with ADHD, children with LD have clear learning difficulties. This does not mean a child is not capable or intelligent; rather, they may struggle in particular areas, such as reading, writing, or math.
• Anxiety and depression: Generalized anxiety, separation anxiety, and social anxiety are common among adults and children with ADHD. While many people may feel worried from time to time, individuals with anxiety worry excessively, to a degree that affects their quality of life. Depression is also more common among individuals with ADHD, which involves feelings of hopelessness, low self-esteem, and difficulty focusing.

The presence of comorbidities can influence the presentation of ADHD and vice versa, which can complicate the diagnosis^[14].

Overlapping symptoms between ADHD and co-occurring conditions may influence prevalence rates, as individuals are often diagnosed with a single condition rather than multiple conditions.

It’s important to take steps to recognize or rule out a dual diagnosis, especially if you recall experiencing or currently exhibiting ADHD symptoms^[15].

What Factors Influence ADHD Prevalence and Diagnosis?

The prevalence of ADHD has risen in recent years. Though many have observed that this rise coincided with the COVID-19 pandemic, studies have suggested that the pandemic did not directly contribute to the increased prevalence of ADHD^[16].

Pinpointing what influences the prevalence rates and diagnosis of ADHD is not an exact science, but studies have pinpointed several contributing factors, including the following:

• Access to healthcare: Where healthcare access is easier, diagnoses of ADHD tend to be higher. In the United States, efforts to improve access to healthcare at the state and federal levels have resulted in more diagnoses^[17].
• Sociodemographic factors: How common ADHD is varies across socio-economic groups. Diagnoses are most common in boys, children with public health insurance, and children living in lower-income households^[18].
• Changes in diagnostic criteria: Whereas only hyperactive children were considered for a diagnosis in the past, the diagnostic criteria have since expanded to include additional inattention-related symptoms^[17]. This broadened understanding of ADHD has resulted in higher prevalence rates^[19]. When comparing ADHD prevalence rates over the years, it is important to consider changes in diagnostic criteria. Broader definitions or updated guidelines may result in more diagnoses, while stricter criteria could lower rates, making direct comparisons over time challenging.
• Increased awareness: The medical community and the general public have become more aware of ADHD and its symptoms, and stigma has declined in recent years^[17]. As a result, individuals have become more capable of recognizing ADHD symptoms and seeking help. Social media platforms like TikTok have played a significant role here, with ADHD-related content garnering billions of views and contributing to a surge in diagnoses, especially among adults and specifically women^[20].

If you suspect that you, your child, or someone you know might have ADHD, it never hurts to see your primary care physician or a psychiatrist who can perform a medical evaluation. While it’s possible to manage symptoms of ADHD independently, having extra support, treatments, and peace of mind can make a big difference to a person’s quality of life.