ADHD

ADHD is difficult to cope with and comes with an additional level of stress that contributes to emotional ups and downs. Forgetfulness and distractions are challenging, and small things like waiting in line can make a person with ADHD quite irritable, as can minor setbacks such as not completing projects on time or changes in deadlines or routines.

 We will take a closer look at the intricacies of ADHD and the tools those with the “disorder” and parents of children with ADHD can use to promote a healthier, more productive, and harmonious life.

Understanding the Causes of ADHD

The underlying causes of Attention-Deficit/Hyperactivity Disorder (ADHD) are not fully understood for most individuals. Research indicates that genetics plays a significant role in the development of ADHD, with studies suggesting a heritability rate ranging from 70% to 80%. This means that the disorder often runs in families and is influenced by genetic factors.

Genetic and Acquired Factors

While genetics is the primary contributor, there are rare instances where ADHD is acquired rather than inherited. Such cases may result from traumatic brain injury, exposure to heavy metals (for example, lead), carbon monoxide poisoning, exposure to certain biohazards or substances during pregnancy, or significant genetic mutations. These factors can disrupt normal brain development, leading to ADHD symptoms.

Neurodevelopmental Nature of ADHD

ADHD is classified as a neurodevelopmental disorder. There is no biologically distinct form of adult-onset ADHD, except in situations where the disorder develops following a traumatic brain injury. The condition arises from atypical development of brain structures, especially those in the prefrontal executive networks. These networks are responsible for executive functioning and self-regulation, and their development can be affected by both genetic variants and acquired disruptions.

Individuals with ADHD often exhibit reduced size, functional connectivity, and activation of brain regions that subserve attention and executive functions. Additionally, imbalances in the noradrenergic and dopaminergic neurotransmitter systems, which modulate the activity of these networks, contribute to the pathophysiology of ADHD.

Role of Environment

It is important to note that the family environment and social upbringing do not play a significant role in the development of ADHD.

IQ Test Performance

Research examining the relationship between ADHD and performance on intelligence quotient (IQ) tests has yielded mixed results. Some studies indicate that individuals diagnosed with ADHD often score lower on standardized IQ assessments. However, the interpretation of these findings remains controversial.

The controversy arises because people with ADHD exhibit a wide range of differences, making it challenging to pinpoint whether lower scores are a reflection of true intellectual capacity or a result of ADHD symptoms—such as distractibility—affecting test performance. Furthermore, many studies investigating ADHD tend to exclude participants with lower IQ scores, which may lead to an overrepresentation of individuals with higher intelligence in research samples. Despite those exclusions, the overall trend suggests that individuals with ADHD score, on average, nine points lower on standardized intelligence measures compared to the general population.

On the other hand, some studies provide a contrasting perspective, reporting that ADHD can be overlooked in individuals with high intelligence. In these cases, compensatory strategies may mask ADHD symptoms, leading to a missed diagnosis. This suggests that the relationship between ADHD and IQ scores is complex and influenced by multiple factors, including test methodology and individual coping mechanisms.

Boys are diagnosed with ADHD approximately 5 to 1 over females. This suggests that ADHD occurs more often in males, but this is likely incorrect. Boys may be diagnosed more often because they are more active and disruptive than girls, and ADHD may affect girls differently. The criteria used to diagnose and treat ADHD were developed and mostly based on the behavior and symptoms of boys. This makes it difficult to accurately diagnose and treat girls.

Relationship Difficulties Associated With ADHD

Social Challenges

Individuals with ADHD, regardless of age or presentation, commonly encounter difficulties with social skills. These challenges often manifest as problems in social interaction and in forming and maintaining friendships. Research indicates that approximately half of children and adolescents with ADHD experience social rejection from their peers, a rate significantly higher than the 10–15% observed in those without ADHD. Difficulties with attention can make it hard for those with ADHD to process both verbal and nonverbal language, which can adversely affect the quality of their social interactions. It is also common for individuals with ADHD to lose focus during conversations, miss important social cues, and struggle to learn and apply social skills effectively.

Hyperfocus and Its Impact

There is a widely reported association between ADHD and hyperfocus, a state characterized by intense and narrow concentration on a specific stimulus, object, or task for an extended period. Hyperfocus typically occurs when an individual is engaged in highly interesting activities or those that offer immediate gratification, such as playing video games or participating in online chat. Although hyperfocus is not officially recognized as a symptom of ADHD in diagnostic manuals, it is frequently discussed in academic literature and commonly observed in clinical practice among individuals with ADHD. Existing studies from 2016, 2019, and 2024 indicate that people diagnosed with ADHD, or those who self-report ADHD symptoms, experience hyperfocus more frequently or intensely than those without ADHD.

A state of hyperfocus may provide benefits, such as enabling individuals to maintain attention on tasks for longer periods than usual. However, it can also present challenges. For example, individuals may find it difficult to disengage and shift their attention to other necessary tasks or stimuli, resulting in excessively prolonged focus that can be detrimental in certain contexts.

Environmental Factors Contributing to ADHD

While genetics plays a major role in the development of ADHD, certain environmental factors have also been identified as potential contributors. For example, alcohol consumption during pregnancy is known to cause fetal alcohol spectrum disorders, which can include symptoms similar to those seen in ADHD. Children who are exposed to environmental toxins, such as lead or polychlorinated biphenyls, may also develop issues that resemble ADHD. Additionally, perinatal exposure to organophosphate insecticides—specifically, chlorpyrifos and dialkyl phosphate—has been associated with a higher risk of ADHD, though the evidence for this relationship is not definitive. Exposure to tobacco smoke during pregnancy can disrupt the development of the central nervous system and is considered a risk factor for ADHD. In particular, nicotine exposure during pregnancy may increase the likelihood of a child developing ADHD.

Other factors that elevate the risk of ADHD include extreme premature birth, very low birth weight, and experiences of extreme neglect, abuse, or social deprivation. Certain infections that occur during pregnancy, at birth, or in early childhood also increase the risk. Furthermore, there is a strong association between traumatic brain injuries and the later development of ADHD; at least 30% of children who experience a traumatic brain injury go on to develop ADHD, and approximately 5% of ADHD cases are attributed to brain damage.

There is some evidence suggesting that, for a small subset of children, artificial food dyes or preservatives may be linked to a higher prevalence of ADHD or ADHD-like symptoms. However, this evidence is generally considered weak and may only apply to children with specific food sensitivities.

Research does not support popular beliefs that ADHD is caused by eating too much refined sugar, watching too much television, bad parenting, poverty, or family chaos; however, these factors might worsen ADHD symptoms in certain people.

Pathophysiology of ADHD

Neurotransmitter Systems

Current models of ADHD indicate that the condition is associated with functional impairments in several of the brain's neurotransmitter systems. In particular, dopamine and norepinephrine are implicated in the disorder. Psychostimulant medications that are commonly used to treat ADHD are effective because they increase the activity of these neurotransmitters, thereby improving symptoms.

Executive Function Deficits

ADHD is characterized by a core deficit in executive functions, which include attentional control, inhibitory control, and working memory. These executive functions are cognitive processes that enable individuals to select, monitor, and carry out behaviors to achieve their goals. When these processes are impaired, individuals with ADHD experience difficulties in staying organized, managing time, controlling procrastination, maintaining concentration, paying attention, ignoring distractions, regulating emotions, and remembering details. Although people with ADHD typically have intact long-term memory, problems with long-term recall are often linked to deficits in working memory.

Developmental Trajectories

The manifestation of ADHD-related impairments can vary according to brain maturation rates and increasing demands for executive control as individuals grow older. As a result, some symptoms may not become fully apparent until adolescence or early adulthood. Conversely, changes in brain maturation trajectories may contribute to improvements in executive functions after reaching adulthood.

Motivational Deficits

Motivational deficits are also commonly associated with ADHD, especially in children. Those affected often struggle to prioritize long-term rewards over short-term ones and may exhibit impulsive behaviors in pursuit of immediate gratification.

Classification

Diagnostic and Statistical Manual

As with many other psychiatric disorders, a formal diagnosis should be made by a qualified professional based on a set number of criteria. In the United States, these criteria are defined by the American Psychiatric Association in the DSM. Based on the DSM-5 criteria published in 2013 and the DSM-5-TR criteria published in 2022, there are three presentations of ADHD:

1.    ADHD, predominantly inattentive presentation, presents with symptoms including being easily distracted, forgetful, daydreaming, disorganisation, poor sustained attention, and difficulty completing tasks.

2.    ADHD, predominantly hyperactive-impulsive presentation, presents with excessive fidgeting and restlessness, hyperactivity, and difficulty waiting and remaining seated.

3.    ADHD, combined presentation, is a combination of the first two presentations.

This subdivision is based on presence of at least six (in children) or five (in older teenagers and adults) out of nine long-term (lasting at least six months) symptoms of inattention, hyperactivity–impulsivity, or both. To be considered, several symptoms must have appeared by the age of six to twelve and occur in more than one environment (e.g. at home and at school or work). The symptoms must be inappropriate for a child of that age and there must be clear evidence that they are causing impairment in multiple domains of life.

Adult Attention Deficit Hyperactivity Disorder

Diagnosis Criteria and Sources of Information

Adults with ADHD are diagnosed using the same criteria as children, with the requirement that symptoms must have been present by the age of six to twelve years. While the individual undergoing assessment is typically the best source of information, input from others—such as family members or close associates—can provide valuable insights into both current symptoms and those experienced during childhood. Additionally, a family history of ADHD increases the likelihood of an accurate diagnosis. Although the core symptoms of ADHD are consistent between children and adults, the way these symptoms manifest can differ; for instance, children may show excessive physical activity, whereas adults might experience persistent feelings of restlessness and continuous mental activity.

Prevalence and Course of ADHD in Adults

Globally, approximately 2.58% of adults are estimated to have persistent ADHD, meaning they currently meet the diagnostic criteria and have evidence of childhood onset. In contrast, 6.76% of adults are thought to have symptomatic ADHD, which indicates they meet the current criteria regardless of whether symptoms were present in childhood. Longitudinal studies suggest that around 15% of children diagnosed with ADHD continue to meet the full DSM-IV-TR criteria at age 25, while about 50% continue to experience some symptoms. Despite this persistence, the majority of adults with ADHD remain untreated. Many of those who are undiagnosed or untreated may lead disorganized lives and may use non-prescribed drugs or alcohol as a means of coping. Additional challenges frequently faced by adults with ADHD include difficulties in relationships and employment, as well as an increased risk of engaging in criminal activities. Commonly associated mental health concerns include depression, anxiety disorders, and learning disabilities.

Differences in Symptom Presentation

The symptoms of ADHD in adults can differ from those observed in children. For example, while children with ADHD may excessively climb or run about, adults often struggle to relax or may speak excessively in social settings. Impulsivity can manifest as initiating relationships rapidly, seeking out new and intense experiences, or displaying a short temper. Adults with ADHD are also at increased risk for addictive behaviors such as substance abuse and gambling.

Onset and Diagnostic Considerations

For an adult to be diagnosed with ADHD, it is generally required that symptoms have been present since childhood. However, there is a subset of adults who meet the criteria for ADHD but were not diagnosed during childhood. Most cases of late-onset ADHD tend to develop between the ages of 12 and 16, and these cases may be regarded as early adult or adolescent-onset ADHD.

Psychiatric comorbidities with ADHD

Neurodevelopmental and Learning Disorders

Other neurodevelopmental conditions commonly occur with ADHD. Autism spectrum disorder (ASD) is present in about 21% of individuals with ADHD and is characterized by difficulties in social skills, communication, behavior, and interests. Learning disabilities are also found in roughly 20–30% of children with ADHD. These may include developmental speech and language disorders as well as academic skills disorders. However, ADHD itself is not classified as a learning disability, although it frequently causes academic challenges for affected individuals. In addition, intellectual disabilities and Tourette syndrome are also observed at higher rates among those with ADHD.

Disruptive, Impulse Control, and Conduct Disorders

ADHD often co-occurs with disruptive, impulse control, and conduct disorders. Oppositional defiant disorder (ODD) is seen in about 25% of children with an inattentive presentation of ADHD and in 50% of those with a combined presentation. ODD is characterized by an angry or irritable mood, argumentative or defiant behavior, and inappropriate vindictiveness for the individual's age. Conduct disorder (CD) is another common comorbidity, particularly in adolescents with ADHD, occurring in about 25% of those with a combined presentation. CD is characterized by aggression, property destruction, deceitfulness, theft, and serious rule violations. The presence of CD in adolescents with ADHD increases the likelihood of developing antisocial personality disorder in adulthood. Brain imaging studies show that CD and ADHD are distinct conditions: CD is associated with reductions in the size of the temporal lobe and limbic system and increases in the size of the orbitofrontal cortex, while ADHD is linked to reduced connectivity in the cerebellum and prefrontal cortex. CD typically involves greater impairments in motivation and control compared to ADHD. Intermittent explosive disorder, which involves sudden and disproportionate outbursts of anger, also co-occurs more frequently with ADHD than in the general population.

Personality Disorders

Borderline personality disorder has been noted to co-occur with ADHD; however, more recent research suggests that this association may be partly due to historical biases that led to misdiagnoses. Diagnostic assessment of each disorder can be complex due to significant symptom overlap. Therefore, differential diagnosis is often necessary to determine if both disorders are present.

Anxiety and Mood Disorders

Anxiety and mood disorders are frequently found alongside ADHD. Anxiety disorders are more prevalent in people with ADHD, as are mood disorders, particularly bipolar disorder and major depressive disorder. Gender differences are apparent: while boys with ADHD are more likely to exhibit externalizing comorbidities, girls tend to internalize symptoms, which can increase the risk of misdiagnosis when using diagnostic criteria developed primarily for males. Both adults and children with ADHD may also have bipolar disorder, which makes careful assessment essential for accurate diagnosis and appropriate treatment.

Sleep Disorders

Sleep disorders commonly co-exist with ADHD and may also arise as side effects of medications used to manage ADHD. In children with ADHD, insomnia is the most frequent sleep disorder, with behavioral therapy often recommended as the preferred treatment. Many individuals with ADHD experience difficulties initiating sleep, yet may sleep deeply and have trouble waking in the morning. Melatonin is sometimes prescribed for children with sleep-onset insomnia. Restless legs syndrome is found more often in people with ADHD, often due to iron deficiency anemia, though it may also be an intrinsic aspect of ADHD. Careful assessment is required to distinguish between these conditions. Delayed sleep phase disorder is another sleep issue commonly associated with ADHD.

Substance Use and Eating Disorders

Individuals with ADHD are at a higher risk for substance use disorders, with the most common substances being alcohol and cannabis. Factors contributing to this increased risk may include alterations in the brain's reward pathways, self-medication behaviors, and elevated psychosocial risk factors. When substance misuse is present, it typically takes treatment priority due to its severity. People with ADHD are also three times more likely to be diagnosed with an eating disorder compared to those without ADHD. Conversely, those with eating disorders are twice as likely to have ADHD as the general population.

ADHD and Suicide

A 2019 meta-analysis indicated a significant association between ADHD and suicidal spectrum behaviours (suicidal attempts, ideations, plans, and completed suicides); across the studies examined, the prevalence of suicide attempts in individuals with ADHD was 18.9%, compared to 9.3% in individuals without ADHD,

Comorbidity of ADHD, Trauma, and Adverse Childhood Experiences

Attention-deficit/hyperactivity disorder (ADHD), trauma, and adverse childhood experiences (ACEs) frequently co-occur, a relationship that may be partially explained by the similarities in their clinical presentation. Both ADHD and post-traumatic stress disorder (PTSD) exhibit significant behavioral overlap, including symptoms such as motor restlessness, difficulty concentrating, distractibility, irritability or anger, emotional constriction or dysregulation, poor impulse control, and forgetfulness. These shared features can lead to diagnostic challenges, with trauma-related disorders sometimes being mistaken for ADHD and vice versa.

In addition, experiencing traumatic events during childhood is a known risk factor for developing ADHD. Such experiences can result in structural changes within the brain and contribute to the emergence of ADHD-like behaviors. Conversely, the behavioral consequences of ADHD symptoms—such as impulsivity and difficulties with emotional regulation—can increase an individual's vulnerability to experiencing trauma. This bidirectional relationship means that ADHD may not only arise from trauma but also predispose individuals to traumatic events, potentially resulting in a subsequent diagnosis of a trauma-related disorder.

Many people who have ADHD also have other issues; for example, at least 50% of adults with ADHD will also develop Anxiety, and almost as many will struggle with Depression. ADHD can be a serious condition if not recognized or treated appropriately. Russel Barkley, one of the leading authorities on ADHD, made the following statement:

“Compared to other killers from a public health standpoint. ADHD is bad. Smoking, for example, reduces life expectancy by up to 6.5 years. For obesity and diabetes, it’s a couple of years. For elevated blood cholesterol, it’s 9 months. ADHD is worse than the top 5 killers combined. Having ADHD costs a person nearly thirteen years of life on average.”

In this statement, Dr. Barkley refers primarily to unrecognized and untreated ADHD. Professional evaluation and treatment change the journey and the destination for those who have ADHD.