Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder affecting 5.9 percent of school-age children worldwide, which, to varying degrees, continues into adulthood for around 50 percent of them. It’s characterized by patterns of inattention, hyperactivity, and impulsivity that make it difficult for sufferers to pay attention and conform to the standards of behaviour expected of them.

The concept of ADHD has a long history, starting as far back as the 18th Century when in 1775, German physician Melchior Adam Weikart wrote the first textbook description of the disorder. A few years later, in 1798, Sir Alexander Crichton, a Scottish-born doctor, referred to it as ‘mental restlessness’ in children. However, it wasn’t until a series of lectures given in 1902 by English paediatrician Sir George Frederic Still, that interest in the condition grew. By the 1960s the American Psychiatric Association (APA) formally recognized it as a mental disorder and included it in the second edition of the Diagnostic and Statistical Manual of Mental Disorders, although at that time it was called ‘hyperkinetic reaction of childhood’. It wasn’t until the revised edition of the manual in 1987 that the name was changed to attention deficit hyperactivity disorder.

In the UK there was scepticism and controversy regarding the existence of ADHD, and virtually no recognition of its importance in children’s education and mental health services until the late 1990s, when it was finally accepted as a valid condition.

Types of ADHD

Some people experience predominantly inattentive symptoms, others experience predominantly hyperactive and impulsive symptoms, and some people experience a combination of both. The disorders (collectively) are found in a 2:1 male-to-female ratio, and the inattentive subtype is more common among the female population.

• Predominantly inattentive presentation: It’s difficult for the individual to organize or finish a task, to pay attention to details, or to follow instructions. They are easily distracted, don’t seem to listen when spoken to, have trouble maintaining daily routines, and frequently lose their belongings.

• Predominantly hyperactive-impulsive presentation: The person is restless and fidgets excessively. It’s hard for them to sit still or remain seated such as when in class, or eating a meal, and smaller children may run, jump, or climb constantly. They talk a lot, often interrupting others. They may grab things from people rather than waiting their turn, and their impulsivity makes them accident-prone.

• Combined presentation: Symptoms of the above two types are equally present.

What causes ADHD?

Research into what causes ADHD is ongoing, but it’s believed that most cases are the result of the combined effects of several genetic and environmental risks, each having a very small effect.

• Genetic: Anywhere from one-third to one-half of parents with ADHD will have a child with the disorder, but no one has yet been able to identify exactly which genes are responsible.

• Environmental: The environmental risks for ADHD exert their effects very early in life, during the foetal or early postnatal period. Examples of possible causes include exposure to lead and nitrogen dioxide, and mothers who smoke or have low vitamin D levels during their pregnancy.

The ADHD Brain

Scientists have also found that there are differences between the development, structure, and function of the brains of people who have ADHD that are key to understanding and treating the condition.

• Development: Neuroimaging studies of the brains of children have shown a delay in those with ADHD of two to five years in the frontal cortex, a brain region associated with abstract thought, decision-making, and short-term memory. This has led to the development of the ‘maturational delay hypothesis’, and may explain why for some, ADHD goes away after adolescence.

• Structure: For those whose ADHD continues into adulthood, several studies have found brain regions including the nucleus accumbens, amygdala, caudate, hippocampus, and putamen, to be up to five percent smaller in people with ADHD. However, a study completed earlier this year (2022) by psychiatrist Joel Bernanke and colleagues, found only modest differences in brain measurements in children aged 9 to 10 years with and without ADHD - so the picture is far from clear.

• Function: The brain is made up of nerve cells called neurons that transmit signals in groups called ‘networks’, and by using methods such as positron emission tomography (PET) which use an injected radioactive tracer that’s tracked as it permeates the brain, researchers have identified deficiencies in the function of neurotransmitters in the brains of individuals with ADHD. This is partly due to reduced levels of norepinephrine or its constituents, including dopamine, which are lower in the brains of people with ADHD compared to a neurotypical brain, and is the reason why stimulants are prescribed to regulate their function.

However, although scientists have shown that there are differences in the brain development, size, and neurotransmitters of people with ADHD, they do not yet fully understand how these differences, combined with the genetic and environmental risks, lead to the cause and symptoms of ADHD.

Growing up with ADHD

Children with ADHD often experience difficulties in the following areas:

• Accidents: They may have more accidents and injuries than their peers due to their impulsive behaviour and lack of concern for the consequences of their actions.

• Completing tasks: Homework, tidying their room, or eating dinner, take them longer, and may not get done at all.

• Irritability: Minor frustrations at home or school can cause substantial irritability. A scenario warranting a 2 on a 10-point scale, for example, can often feel like a 7 or 8 to a person with ADHD. They can be quick to anger as a result, and may lash out aggressively.

• Relationships: They’re more likely to have trouble interacting with, and being accepted, by peers and adults.

• Hyper-focus: Although easily bored, they may hyper-focus on tasks that interest them, to the detriment of essential activities such as sleeping and eating.

• Forgetfulness: They may forget things such as their sports kit, lunchbox, or homework - even when it’s been completed.

• Sleep: They often have problems getting to sleep, staying asleep, and waking up on time.

• Underachievement: They may be disruptive at school and underachieve, even though they have a lot of talent and potential.

• Low self-esteem: They often develop low self-esteem after years of not meeting their own, and other people's, expectations.

• Delinquent behaviour: They’re at increased risk of smoking, alcohol and drug abuse, and other delinquent behaviour.

ADHD in Adults

For the 50 percent or so whose ADHD continues into adulthood, there comes the realisation that they no longer have to conform to the behaviours expected of them by their parents and teachers. They now have more control over their environment, and the opportunity to choose a career and lifestyle that works with their symptoms.

For example, those with hyperactive ADHD could pick a job that doesn’t involve sitting at a desk for long. They might work outdoors as a gardener or become a salesperson who uses their car as a traveling office. For others, the freedom offered by self-employment is the goal. And although their hyperactivity is still there, as an adult they have greater control over their restlessness, so that the casual observer is probably unaware of it.

Sadly, according to the International Consensus Statement on ADHD published in 2021, people with ADHD are at increased risk for low quality of life, substance use disorders, accidental injuries, educational underachievement, unemployment, gambling, teenage pregnancy, difficulties socializing, delinquency, suicide, and premature death. Read the full report here.

However, that may be because the majority of people with ADHD also have one or more co-existing conditions.

Co-existing conditions

Research has shown that more than 65 percent of people with ADHD have at least one co-existing conditions, many of which have symptoms that can mimic ADHD, and may in fact, be exacerbating their difficulties. So it’s essential that they are also diagnosed and treated.

• Learning disabilities: Almost 50 percent of children with ADHD have a coexisting learning disorder such as dyslexia, which affects their ability to read, write, understand, and communicate.

• Oppositional defiant disorder (ODD):  About 40 percent of children with ADHD have ODD, defined as a pattern of negative, defiant, and hostile behaviour toward authority figures. Those diagnosed with ODD are generally described as being angry, resentful, spiteful, and vindictive. Most will outgrow it, but for some, it may turn into Conduct Disorder.

• Conduct disorder (CD): Marked by antisocial behaviour such as stealing, fighting, destroying property, and harming people or animals. CD occurs in around 27 percent of children, 47 percent of adolescents, and 23 percent of adults with ADHD, and is a strong driver for criminal activity.

• Disruptive mood dysregulation disorder (DMDD): Characterized by persistent irritability, punctuated by intense temper tantrums that are disproportionate to the situation. About 20 percent of those with ADHD qualify for a diagnosis of DMDD, and about 90 percent of children with DMDD meet the criteria for ADHD.

• Substance use disorders (SUD): Research suggests that young people with ADHD are at increased risk for very early cigarette use, followed by alcohol, and then drug abuse. Young people with ADHD are twice as likely to become addicted to nicotine as those without ADHD, and adults with ADHD have elevated rates of smoking and report particular difficulty in quitting.

• Anxiety disorders: Around 30 percent of children and 50 percent of adults with ADHD may also have an anxiety disorder, which is three times higher than that experienced by the general population.

• Sleep disorders: Up to 50 percent of parents of children with ADHD report that their children suffer from a sleep problem, especially difficulties with falling asleep and staying asleep.

• Mood disorders: Mood disorders are characterized by extreme changes in mood, and include depression, mania, and bipolar disorder. Approximately 14 percent of children with ADHD have depression, compared to only 1 percent of children generally. In adults with ADHD that figure increases to approximately 38 percent, whereas, in the general population it’s around 5 percent.

• Autism spectrum disorder (ASD):  More than 13 percent of children with ADHD are diagnosed with ASD, a condition related to brain development that impacts how a person perceives and socialises with others.

• Tic disorder or Tourette’s syndrome: Less than 10 percent of those with ADHD have tics or Tourette’s Syndrome, but 60 to 80 percent of those with Tourette’s syndrome have ADHD. Tics involve sudden, rapid, recurrent, involuntary movements or vocalizations. Tourette’s syndrome is a much rarer, but more severe tic disorder, where patients may also make noises, such as barking a word or sound.

Diagnosing ADHD

Diagnosing ADHD in children and adults is carried out by a psychiatrist, psychologist, or psychotherapist who specialises in ADHD, and depends on a set of strict criteria set out in the International Classification of Diseases (ICD) published by the World Health Organisation (WHO), or the Diagnostic and Statistical Manual of Mental Disorders (DSM) used by clinicians in the United States (US).

Regardless of which medical classification system is used, the features and descriptions of ADHD in the current editions of each manual are very similar. To be diagnosed with ADHD children must have six or more of the nine characteristics listed, and older teens or adults must have had at least five of the characteristics prior to reaching age twelve. There should also be clear, corroborated evidence that symptoms interfere with, or reduce, the level of social, academic, and occupational functioning. This will involve a variety of methods including behaviour and symptom checklists, psychological tests, and interviews or written observations from teachers, parents, or family members who can shed light on the patient's developmental history and childhood behaviour.

When diagnosing ADHD, clinicians now also need to specify whether a person has mild, moderate, or severe ADHD. This is based on how many symptoms a person has and how difficult those symptoms make daily life. Something I noted whilst I was researching this subject is that recent editions of both diagnostic manuals have widened the definition of ADHD, which has resulted in an increase in the number of people being identified with the condition, particularly those with mild to moderate symptoms. This has been viewed with concern by some clinicians because they question whether the increase may, in part, be due to overdiagnosis or misdiagnosis.

Girls and women with ADHD

For a long time, it was thought that ADHD was primarily a condition in boys and some men. However, while girls are still diagnosed with ADHD at just under half the rate of boys, in adulthood, women and men are now diagnosed with ADHD at roughly the same rate. That’s thought to be because girls more often exhibit the predominantly inattentive presentation of ADHD that is less apparent than the predominantly hyperactive-impulsive presentation of ADHD usually seen in boys. It’s only later in life, when they’re juggling home, family, and work responsibilities, that women may struggle to make sense of the difficulties they’re having, and an ADHD diagnosis is finally made.

Treating ADHD

Treatment options for people with ADHD include medication, cognitive behavioural therapy, occupational therapy, ADHD coaching, and neurofeedback. These interventions can be tailored to the patient’s and family’s needs, and while they won't cure the disorder, they can help the patient control symptoms, manage social relationships, and improve their overall well-being. Behaviour therapy and school supports and accommodations are also available for children and adolescents.

• Medication: Central nervous system (CNS) stimulants are the most widely used medications for the management of ADHD symptoms in children, adolescents, and adults. They work by increasing the amounts of brain chemical norepinephrine, which produces a paradoxical calming effect. This results in a reduction in hyperactivity, and an improvement in attention span in many people, which improves concentration and focus.

o   Stimulants: Amphetamine, Aextromethamphetamine, Dexmethylphenidate, Methylphenidate, Lisdexamfetamine. This group of drugs has treated ADHD for several decades.

o   Non-stimulants: Atomoxetine, Guanfacine, Clonidine, Bupropion, Viloxazine. For use in cases where stimulants don’t work or cause unpleasant side effects.

• Cognitive behavioural therapy (CBT): A form of psychotherapy in which the therapist works with the patient to explore their thoughts, feelings, and behaviours in order to challenge and change negative patterns of thinking. The therapist then assists the client to reframe the way they feel about themselves and their symptoms, and to implement effective strategies that will modify their behaviour and alleviate their symptoms.

• Behaviour therapy for children: Addresses problem behaviours by establishing predictability and routines, increasing positive attention, discouraging negative behaviour, and reinforcing good behaviour with a reward system.

• Occupational therapy (OT): Helps people to succeed at home, at work, at school, and in their leisure time. This may involve building skills in planning, organising, time-management, and setting priorities, as well as establishing routines such as those required to maintain personal hygiene.

• ADHD coaching: While not a traditional form of therapy, ADHD coaching can help children, adolescents, and adults to identify goals and maintain focus to achieve a balanced, happy, and healthy lifestyle. More specifically, coaches can help their clients to achieve emotional and intellectual growth and make conscious and wise choices.

• Neurofeedback: A non-invasive procedure that measures a patient’s brainwaves and provides the patient with real-time feedback about how the brain is functioning. Research has shown that the brain changes in response to stimulation, known as neuroplasticity, and ADHD brains that have deficits in one area will attempt to rewire themselves to accomplish a task. By training the brain to emit brain-wave patterns associated with focus, as opposed to those associated with (for example) daydreaming, neurofeedback helps patients to gain control over certain functions that they are typically not aware of.

Diet and ADHD

Despite numerous studies, the relationship between diet and ADHD remains unclear. However, a recent (October 2022) systematic review of the literature found that non-healthy dietary patterns (high in processed meats, refined grains, hydrogenated fats, artificial food colouring, and sugar) were positively associated with ADHD, whereas healthy patterns (high in fruits and vegetables, polyunsaturated fatty acids (PUFAs) and micronutrients such as magnesium and zinc) were negatively associated. As for nutritional supplements, only vitamin D and vitamin D + magnesium appeared to improve ADHD symptoms when baseline levels of vitamin D were deficient. Regarding biotics, evidence was only found for lactobacillus rhamnosus GG and for multi-species probiotic supplementation. Overall, more robust scientific evidence is required for these dietary interventions to be implemented as part of ADHD therapy. Read the full report here.

And now for the good news…

Although the focus is usually on the difficulties faced by people with ADHD, there are many who live happy and productive lives, especially if they receive treatment, and for some, the unique skills and characteristics they’ve developed as a result of their condition have given them advantages that set them apart from their peers.

• High Energy Levels: People who have hyperactivity as a symptom of ADHD have high energy levels. This sometimes presents with symptoms such as restlessness, fidgeting, and excess talking, but on the other hand, it can be a powerful driving force for those who are able to find ways to harness it and channel it productively.  

• Hyperfocus: People who have ADHD often experience hyperfocus, which involves becoming intensely focused on a particular task or subject. It can sometimes cause problems if it interferes with other areas of life, but it can also help people concentrate, finish tasks, and learn a great deal about a topic. This is similar to what psychologist Mihály Csíkszentmihályi refers to as the state of flow, which is defined as a period of intense concentration, attention, and absorption in an activity that produces strong feelings of enjoyment.

• Spontaneity: Impulsivity is another common symptom of ADHD. While it’s often characterised as acting without thinking, being impatient, and interrupting others - for those who are able to manage it effectively, it enables them to be spontaneous, lively, and open to new experiences.

• Creativity: While people with ADHD can be inattentive and easily distracted, they also tend to be divergent thinkers. A different perspective and original ideas can be a benefit in most careers. Instead of following fixed patterns and ways of thinking about problems, they’re able to spot new solutions and come up with innovative ideas, and research has found that people with ADHD perform better on real-time creative tasks than those without it.

• Resilience: People living with ADHD face daily challenges and obstacles. Having the ability to cope with the stress, and to create strategies to accomplish their goals, is why adults with ADHD are often more resilient than their neurotypical peers.

• Self-Awareness: People with ADHD often develop an increased sense of self-awareness because they frequently have to monitor and regulate their behaviour to be sure that they’re not being disruptive or acting inappropriately.

There’s no disputing that ADHD is a complex disorder that can make life difficult. But it’s also clear that people who have ADHD have a wide variety of skills, talents, and abilities that some refer to as their ‘superpowers’. Here are the names of just a few you may have heard of: John F. Kennedy, Richard Branson, Justin Timberlake, Whoopi Goldberg, Simone Biles, Emma Watson, will.i.am, Ryan Gosling, Karina Smirnoff, Pablo Picasso, Adam Levine, Jim Carrey, Thomas Edison, Michael Phelps, Michelle Rodriguez, Dave Grohl, Woody Harrelson, Jamie Oliver, Howie Mandel, Solange Knowles, Salma Hayek, Tom Hanks, Lee Mack, Bill Gates, John Lennon, Mel B, Michael Jordan, Mozart, and Leonardo Da Vinci.

While people tend to associate ADHD with children, there’s growing awareness that it can affect adults as well. So, if you’re concerned that you or someone you know may have the condition, discuss it with a healthcare provider. It’s never too late to get a diagnosis.

Thank you for reading this blog post. If you have any thoughts to share, or ideas for future posts, please do let me know. I would love to hear from you.