Brief historical review of ADHD and its impact on executive functioning

The psychologist, professor, researcher, and master’s degree holder in human development and education, Carolina Robledo Castro, offers us in this article a brief overview of the history of ADHD and how it affects the executive functioning of those who suffer from it.

What is ADHD?

Currently, Attention Deficit Hyperactivity Disorder (ADHD) is the clinically endorsed term to refer to a neurodevelopmental disorder characterized by behaviors of inattention, impulsivity, and hyperactivity (APA, 2013). However, this concept remains a developing psychological construct, which has undergone different conceptions and approaches over the decades and will surely continue to evolve.

Clinical evolution of ADHD

Alexander Crichton

The first clinical approaches to what we now know as ADHD can be observed since the 17th century when the physician Alexander Crichton, based on various clinical observations, published a work titled “On Attention and its Diseases,” describing a condition characterized by the inability to sustain attention to any object accompanied by constant motor restlessness, which he called mental agitation, resembling the current description of ADHD (Lange, 2010).

Heinrich Hoffmann

References to ADHD manifestations can also be found in the writings of physician Heinrich Hoffmann in 1844. Hoffmann wrote a series of illustrated stories describing the impulsive and inattentive behavior of a child he named “Struwwelpeter,” stories based on his own observations of his son (Filomeno, 2007). While Hoffmann’s approach was not clinical, the story of Struwwelpeter is often used as an allegory for ADHD (Lange, 2010).

George Frederic Still

In the field of pediatrics, one of the first to clinically address this condition was George Frederic Still, who in 1902 described a pattern of behavior in children who exhibited inattention and seemed to lack control over their conduct.

Initially, Still attributed this behavior to a defect in moral control, but later associated it with a possible neurological or hereditary condition (Robledo, 2017; Filomeno, 2007). Later on, this profile of inattention and impulsivity was associated with encephalitis lethargica during the epidemic that occurred between 1917 and 1928, as the affected individuals presented similar cognitive and behavioral alterations:

• Significant changes in personality.
• Emotional instability.
• Cognitive deficits.
• Learning difficulties.
• Poor motor control.

This condition was referred to as “minimal brain damage” and persisted until the 1970s when it was renamed “minimal brain dysfunction” (Lange, 2010).

ADHD from the 1930s to the 1960s

Between the 1930s and 1950s, the medical community placed particular emphasis on the symptoms of impulsivity and hyperactivity over cognitive manifestations, and the term changed to “hyperkinetic syndrome,” referring to significant motor activity that prevents children from staying still even for a second.

During the 1960s, with the influence of behavioral perspectives, notable work began by authors such as Stella Chess, and it started to be referred to as “hyperactive child syndrome” (Robledo, 2017).

Finally, in 1968, this condition was first included in the Diagnostic and Statistical Manual of Mental Disorders, DSM II (APA, 1968), under the name “hyperkinetic reaction.”

ADHD from the 1970s to the 1990s

The difficulty of sustained attention and lack of impulse control regained recognition in the 1970s through the work of Virginia Douglas (Douglas, 1972). By the 1980s, the Diagnostic and Statistical Manual of Mental Disorders in its third version established that hyperactivity was not a differential diagnostic criterion for the disorder. Instead, it coined the term “Attention Deficit Disorder” (ADD) and indicated that it could present two types: with hyperactivity and without hyperactivity (APA, 1980).

In the early 1990s, the DSM-IV coined the term “Attention Deficit Hyperactivity Disorder” (ADHD) and expanded the classification of this disorder by distinguishing subtypes: predominantly inattentive, predominantly hyperactive-impulsive, and combined (APA, 1990).

During that time, this disorder was categorized in the group of disorders of infancy and adolescence, specifically in the classification of attention-deficit and disruptive behavior disorders.

ADHD from the 1990s to the present

From the 1990s to the present, advances in neuroscience, genetics, diagnostic imaging, and computational modeling have contributed to new knowledge that has expanded the conceptualization and approach to Attention Deficit Hyperactivity Disorder.

With the latest diagnostic manual, DSM-5, some significant changes were incorporated that have influenced the conceptualization and understanding of ADHD. While many diagnostic criteria were retained from the previous version, ADHD has been included in the neurodevelopmental disorders category alongside others such as autism spectrum disorder. Additionally, for the first time within the diagnostic criteria, it is acknowledged that this condition is not exclusive to childhood but can persist into adolescence and adulthood. It is also differentiated into mild, moderate, and severe levels (APA, 2013).

As a result of over 40 years of work with children, adolescents, and adults exhibiting this behavioral pattern, Russell Barkley (2002) stated, “I now see ADHD as a disorder of the developmental regulation of behavior and foresight” (p.35).

Barkley, supported by scientific advances at the time, concluded that ADHD stems from the hypoactivity of a brain area responsible for providing greater resources for behavior inhibition, self-regulation, self-organization, and future planning as the individual grows and this neurological area matures. In addition, this hypoactivity leads to a deficit in individuals’ ability to regulate their daily functioning, adapt to environmental demands, and prepare for the future.

In the 2000s, scientific findings confirmed alterations in biochemical mechanisms in the prefrontal cortex in individuals with ADHD, particularly in the neurotransmitters dopamine and norepinephrine (Nigg, 2006; Duda, 2011).

Neuroimaging research suggests a possible delay of up to three years in the maturation of the prefrontal cortex in those with ADHD (Shaw, 2007), as well as an association between ADHD and alterations in volume and activation levels in prefrontal regions related to executive functions (Seidman et al., 2005).

Based on these findings and other clinical discoveries, authors such as Brown (2002) and Barkley (2011) have suggested that ADHD is not primarily originated from attention deficit but rather as a result of a synaptic alteration in certain brain areas, including the prefrontal neocortex, which play a crucial role in regulation and cognitive control. Consequently, it has been concluded that deficits in organization and self-management in individuals with ADHD are linked to the alteration in executive functioning (Barkley, 1997; 2011).

What are executive functions?

Executive functions (EF) are cognitive processes that allow the individual to internalize behaviors to anticipate future changes and thus maximize the individual’s long-term benefits (Barceló, 2005; Flores & Ostrosky-Shejet, 2012).

They are precursors to successful self-regulation (Kalbfleisch, 2017), thereby being crucial for school learning, following instructions, complying with rules, and overall performance in daily life.

They are involved in the completion of goal-directed tasks, those that involve reviewing options, organizing, planning, monitoring execution, foreseeing future consequences, evaluating performance, and adapting to new situations (Portellano & García, 2014). In other words, these cognitive processes make it possible to plan, organize, guide, review, regulate, and evaluate behavior in goal achievement.

Executive functions affected by ADHD

According to Brown (2008), the affected EF in people with ADHD are as follows:

1. Activation, required for organizing tasks and materials, estimating time, establishing task priorities, and initiating activity.
2. Focus, necessary to focus and sustain attention, as well as shift focus of interest.
3. Effort regulation, including managing alertness levels, fatigue tolerance, and processing speed.
4. Emotional management, enabling the individual to handle frustration and control emotions.
5. Working memory, responsible for holding incoming information and recalling stored information until a task is completed.
6. Action control, allowing behavior monitoring, learning from mistakes, and inhibiting automatic and impulsive responses.

Challenging activities due to ADHD

Based on the findings by Brown (2008), Beatriz Duda (2011) provides a description of activities associated with executive functioning that are often challenging for children, youth, and adults with ADHD, which have been compiled in the following table.

Executive function (Brown, 2008)	Subfunction	Activities that are difficult for people with ADHD (Duda, 2011)
Focus: Ability to focus attention on what is important, maintain and shift attention to certain tasks.	Focalize	Focus their attention on what is important. E.g., pay attention to the teacher instead of talking to classmates.
	Maintain focus	Sustaining attention for as long as a class lasts. Or alternate attention between two tasks.
	Flexibility	E.g. Stop searching the internet and start writing.
Action: Ability to evaluate one’s own behavior, recognize difficulties, self-regulate oneself, inhibit impulses and automatic behaviors.	Inhibition	Avoid automatic behaviors, waiting for turns, delaying rewards. E.g. Running out at recess.
	Self-monitoring	Manage time efficiently. Recognize mistakes and successes as lessons learned for future situations.
Emotion: Ability to control and manage affective states, reacting with the appropriate emotional level to circumstances.	Frustration management	Remain calm when things are not going his way.
	Emotion management	React appropriately to situations. E.g., yelling or hitting when something bothers them.
Working memory: Ability to retain in the mind information needed to follow actions.	Retain	Holding necessary information while performing a task. E.g. In a conversation, not remembering what you were talking about, after being interrupted.
	Evoke	Accessing important information. E.g. Studying for a test and not remembering it at the time of the exam.
Sustained effort: Regulation of alertness, sustaining effort, and speed of information processing.	Processing speed	Complete tasks in the allotted time. E.g. They need more time than other classmates to complete a task.
	Maintenance of effort	Fatigue tolerance. E.g., their attention spans burn out faster than other children.
	Regulating alertness	Maintain their alertness in activities that are not motivating.
Activation: Ability to activate to work, prioritize, and plan actions based on projected goals over time.	Activate	Get up in the morning and start the day’s activities. Stop playing and start doing homework.
	Prioritize	Decide what to do first and prioritize actions. E.g. Start many things at the same time.
	Organize	Maintaining order. E.g. Difficulty in planning how to resolve a situation.

Intervention and rehabilitation of executive functions in children with ADHD and without ADHD

Regarding the intervention and rehabilitation of executive functions in children with ADHD and without ADHD, Diamond (2011; 2012) distinguishes four types of interventions that have shown promising results:

1. Cognitive training.
2. Mindfulness practices focused on attention regulation.
3. Curriculum approaches with emphasis on cognitive scaffolding.
4. Programs centered on social skills and emotional regulation.

Computerized cognitive training

Computerized cognitive training has been one of the most implemented interventions to improve executive functions and reduce symptoms of impulsivity and inattention in the context of ADHD (Pauli-Pott et al., 2021; Robledo et al., 2023).

This type of intervention seeks to optimize cognitive functioning through the practice of intentional instructions and distinguishes two paradigms:

1. One based on processes, where the individual repeats the execution of a task.
2. Another based on strategies, where various strategies are explored to tackle a specific task (Jolles and Crone, 2012; Portellano, 2018).

Some systematic reviews and meta-analyses have compiled evidence from clinical studies and controlled trials in which computerized cognitive training has been implemented for stimulation and rehabilitation of executive functions in the ADHD population (Sonuga-Barke et al., 2014; Alabdulakareem and Jamjoom, 2020; Robledo et al., 2023).

These works have found that computerized cognitive training had effects on:

1. Attention and memory.
2. Reducing ADHD symptoms in children and adolescents (Sonuga-Barke et al., 2014).
3. Positive effects on executive functions such as attention, inhibitory control, and working memory (Robledo et al., 2023).
4. Improvements in academic performance and self-control in children with ADHD.
5. Greater satisfaction and adherence to treatment (Alabdulakareem and Jamjoom, 2020).

While evidence has been collected to date on the uses and benefits of computerized cognitive training on the executive functions of children and ADHD symptoms, this remains a field of study still in development that undoubtedly has broad relevance and interest for the academic community, as well as for all professionals in charge of the care and intervention of the ADHD population.

Bibliography

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