Attention Deficit Hyperactivity Disorder (ADHD) - Clinical Case Series #1
Adapted by Prof. Henry O'Connell from chapter 4 in his book "Evolution and Psychiatry: Clinical Cases" - Edited by Dr Gurjot Brar
Welcome to the first in a series of clinical cases, exploring common mental disorders through the lens of evolutionary psychiatry. A ‘problem-based learning’ (PBL) approach is taken with learning outcomes defined at the outset, followed by several clinical encounters with fictional scenarios, interspersed with theory responding to the learning objectives. This method has emerged globally in medical curricula and has a good evidence base in medical education promoting self-directed learning. We hope you enjoy this format and look forward to your feedback.
This case series will often refer to key principles defined in the following article published in July 2023 which serves as a primer:
Attention Deficit Hyperactivity Disorder (ADHD)
Learning Objectives
1. Outline briefly the key facts about ADHD relating to clinical features and diagnostic criteria, epidemiology, aetiology, pathophysiology and management.
2. Describe the evolutionary principle of ‘environmental mismatch’ and how this can be applied to ADHD.
3. Describe the principle of ‘fast life history’ strategies and how this can help our understanding of ADHD.
4. Outline how the evolutionary perspective can help inform treatment strategies for ADHD.
5. Outline how the evolutionary perspective can help inform research strategies for ADHD
Clinical station 1: ‘This kid’s in trouble’
You are a Consultant Psychiatrist working in Child and Adolescent Mental Health Services (CAMHS) in a large Irish town. You receive a referral from one of your Family Doctor colleagues marked ‘urgent’. The referral is as follows:
Dear Dr Sullivan,
Please see Mark Ryan and advise on treatment. He is aged seven and comes from a good, stable family. Both of his parents are patients with my practice. His father is a successful musician and his mother works as a secretary.
Mark seems not to be fitting in at school, to say the least. Problems have been evident since he started at school two years ago but they are now coming to a head. The teachers say he never listens, he is constantly out of his desk running around the classroom and he is always in trouble, fighting with other children and giving cheek to the teachers.
I really think that this kid’s in trouble. The school is limited in resources to cope with him. His teacher thinks there’s more going on than just naughtiness, as does his mother. His father seems to think that Mark will just ‘grow out of it’. The problem is that I think the teachers are starting to lose patience with him and there have been complaints from the parents of other children. Mark has got a real reputation at this stage.
He is a healthy boy in all respects, with vaccines up to date and no history of any medical problems. I met with him recently with his mother and I did find him to be a little forward and fidgety, but I cannot see evidence of any major psychiatric or neurological disorder. He seems to be very clever, well ahead of most of the rest of his classmates in many respects, but he is easily distracted and loses interest in classroom activities after only a few minutes. He does not appear to have any sensory issues such as hearing or visual impairment, he is good at sports such as football although a little clumsy and rough at times.
This may well be a case of ADHD and if it is then he’s surely a child who would benefit from medication. But I know that there may be some objection from his parents, especially his father, regarding this approach. On the other hand, he may just be a difficult child who needs a firmer hand from his parents and the school. Whatever the case, I cannot see him lasting much longer in the school unless something is done about his behaviour.
Many thanks,
Dr Michael Gaffney
The referral is discussed at your multi-disciplinary team meeting and, in view of the level of concern expressed by the Family Doctor, it is agreed that you will do an initial assessment within the next week.
You meet with Mark and his parents in your office. Mark comes straight up to you and says: ‘That’s a stupid looking tie you’re wearing’, then starts laughing. You notice that his father smiles at this and then his mother gives the father a stern look. You offer Mark some toys in the corner of the room and he rushes off to start playing with them. His parents sit down and you go through Dr Gaffney’s referral with them. They have brought Conners questionnaires, given to them by Dr Gaffney and completed by themselves and Jack’s teacher. The results are highly indicative of Mark being in the ADHD range, with significant scores in the areas of inattention, hyperactivity and impulsivity.
You go through Mark’s developmental and medical history, which is unremarkable. He has two younger brothers who are much quieter and more compliant than Mark. The parents confirm that Mark had trouble settling in class from when he started in primary school at the age of five but that these problems have now become more evident. His mother has read up on ADHD and she feels that he has many of the features. During the consultation, you notice how Mark is playing with the toys: he makes lots of noise and goes quickly from one toy to the next. He also comes over frequently and interrupts his parents, asking when they can go home and if will he be getting an ice-cream for being quiet.
‘In your experience as a Child Psychiatrist, can you tell me if it’s ADHD that we’re dealing with here?’, his mother asks. ‘You see, doctor, my husband doesn’t believe in ADHD. He thinks it’s an American invention, designed to create a market for drug companies’. You outline the key facts about ADHD (see Learning Objective 1 below). As you talk, you notice that Mark’s father seems sceptical and uninterested in what you’re saying. You reflect this observation back to him, asking for his opinion on things. He looks at his wife and then at Mark and then back to you. ‘I would prefer to call you about this separately, doctor. You see, I have a very different view to my wife and the teachers as to what’s going on. And I don’t want his whole thing to descend into a big argument. Especially not in front of the little man there. We’ve had enough of those’. You make a plan to call Mark’s father later to get his take on things.
Learning Objective 1:
Outline briefly the key facts about ADHD relating to clinical features and diagnostic criteria, epidemiology, aetiology, pathophysiology and management
ADHD is classified as a neurodevelopmental disorder, with onset in early childhood and characteristic core features of inattention, hyperactivity and impulsivity. The symptoms and behaviours are pervasive in that they occur across all settings, e.g. at home and in school, and children with ADHD are likely to have impaired academic performance and behavioural difficulties.
Prevalence rates vary widely between countries, with as many as 9% of US children diagnosed in comparison to as few as 0.5 % of French children (Wedge, 2012). This wide variation may be related to cultural differences in terms of expectations of child behaviour and academic performance. Children born just before the cut-off for the next academic year are 2.5 times more like to have an ADHD diagnosis (Krabbe et al., 2014), indicating the potential importance of developmental aspects in diagnosis of ADHD. The condition is generally far more common in boys than girls, with the male: female ratio being reported as ranging from 3:1 in Norway to 16:1 in Austria (ADHD Institute, 2016).
Multiple aetiological factors have been implicated, including genetic factors related to dopamine, noradrenaline and serotonin activity (e.g. carriers of the long allele of the DRD4 7 repeat gene have a higher, expressed at the D4 receptor in the prefrontal cortex), trauma, neglect and suboptimal parenting styles. Overall risk for ADHD is likely mediated by multidirectional relationships between the child’s genotype and environmental factors but concordance rates for monozygotic twins have been reported as being as high as 60-88%. Additionally, epigenetic research has shown a ‘differential susceptibility to rearing’, suggesting some children are genetically more susceptible to the influence of their environments than others (Belsky & Hartman, 2014).
Comorbid neuropsychiatric conditions are common, including anxiety disorders, depression, substance use disorders and Tourette syndrome. Evaluation and diagnosis should consider such comorbid conditions while also assessing for developmental delay, sensory impairment and learning difficulties.
Pathophysiological differences, although heterogenous, are well described in children with ADHD and these include reduced grey and white matter volume in the frontal and temporal lobes, reduced caudate nucleus volume, cerebellar abnormalities and reduced thickness of the rostral part of the corpus callosum.
Treatment with dopaminergic stimulant medications is generally well tolerated and leads to improved behavioural and academic outcomes. Behavioural strategies are also effective and include reward-based systems. Persistence into adulthood occurs in up to half of those with ADHD in childhood, although the symptom profile may change, with inattentiveness features becoming relatively more prominent than hyperactivity.
Clinical station 2: ‘All the men in my family are a bit like that’
Later on, in the afternoon of the initial assessment, you call Mark’s father as planned. ‘Thank you for meeting with us earlier, doctor’, he begins. ‘I hope I didn’t come across as being dismissive, but I have my doubts about the whole ADHD thing generally. Then when you gave us the facts and figures and told us about actual brain differences it started to make a bit more sense to me. But I do have to say that Mark is a great boy, although I know I’m biased. And I do have to say that I too was ‘wired’ when I was his age, as were my brothers, his uncles. In fact, all the men in my family are a bit like that. We were all in to hiking and motorbikes and football and music. We grew up on a farm and we were out in the fresh air delivering calves and mending fences when we were not much older than Mark. But we’re now living in an apartment in the town and Mark only gets out to the park once a day. None of us Ryan boys had any interest in school. We had a reputation for being wild, but we settled down and found our own ways in life. I think my wildness and sense of adventure is why my wife took an interest in me in the first place! Oh, and I hated school. I remember just sitting on the edge of my desk during classes watching the clock all the time, then bursting out onto the football field at break-times and running around and screaming’. You acknowledge all of this information and make a note in Mark’s file.
He goes on: ‘You see, doc, I don’t want Mark to be medicated so that he ends up losing his ‘Ryan-ness’. I know that if he finds an interest that he will throw himself into it and excel. That’s what I was able to do with music. Is there any other option available apart from medication? I know it seems to help, and I know about the ADHD brain differences as you described them, but medication for a seven year old child seems to be drastic. I’ve noticed that he seems to be more settled and focused after he’s had a good run around and had a chance to let off some steam. Would that be an option? And on another point, I wonder do I and my brothers all have this ADHD condition?’
You reiterate the information about ADHD covered in your first meeting with Mark’s parents (see Learning Objective 1 above) and then you give Mark’s father further details, based on an evolutionary synthesis of the condition, addressing the principles of environmental mismatch and ‘fast life history’ strategy.
(See Learning Objectives 2 and 3 below)
Learning Objective 2:
Describe the evolutionary principle of ‘environmental mismatch’ and how this can be applied to ADHD
Randolph Nesse (2018) has outlined six main reasons for why evolution has left us all vulnerable to illness. One of these six evolutionary reasons relates to the issue of ‘mismatch’, i.e. between our bodies and minds that have evolved over hundreds of thousands of years in pre-industrial and indeed pre-agricultural settings and our current modern and often quite artificial environments. A classic example relates to tastes and appetites for certain foods. In our pre-agricultural background (where we as a species have spent the vast majority of our evolutionary history), a proclivity for then minimally available sugary, salty and fatty foods would have been advantageous. In contrast, in many modern environments, access to such food types is now cheap and limitless and so our ‘stone-age’ appetites can lead some of us to excessive consumption, thus developing all kinds of dietary related problems such as obesity, diabetes and some cancers.
The concept of environmental mismatch can also be applied to neurodevelopmental disorders such as ADHD. An evolutionary perspective on this condition asks ultimate causation questions not just about how the condition manifests and is mediated at the neurotransmitter level, but why it exists at all, especially at such high rates in certain countries such as the United States. One evolutionary perspective theorises that the core features of ADHD (i.e. inattentiveness, hyperactivity and impulsivity) may have had some adaptive roles at some stages of our evolutionary past, hence the persistence of the condition until now. And while caution should always be exercised to avoid jumping to hastily constructed adaptionist conclusions and viewing diseases as adaptations (VDAA), such an approach may be helpful in the example of ADHD. Another theory based on systems, may explain ADHD as the severe and dysfunctional extreme of disruption associated with the normal regulation of attention, activity and impulse control. Similar to mood disorders, where the proposed ‘moodostat’ can go awry, it is possible that as we all have capacities for attention, activity and impulse control, that those with ADHD represent the pathological extreme.
Specifically, it is plausible to consider that individuals with ADHD traits in our evolutionary past may have outperformed others in terms of hunting, gathering, exploring, risk taking, competing for mates and even in combat with other humans. However, when individuals with such traits are expected to sit still for long periods in modern indoor classroom settings and attend to academic pursuits, then the evolutionary formulation follows that they may not be able to comply and may thus be perceived as having a disorder, namely ADHD. The absence of an evolutionary perspective may thus lead us to make the error of viewing symptoms as disease (VSAD).
However, all of the above is theorising and we must always be wary of overly simplistic and ‘just so’ narratives within the evolutionary perspective. We must also look for testable questions and attempt to back up our theories with objective evidence.
One such piece of evidence relates to a study by Eisenberg and colleagues (2008) looking at a Kenyan population, comparing a group of nomadic farmers with close relations who had recently settled. In those with genotypes that would normally be associated with ADHD traits (7 repeat variant of the Dopamine DRD4 receptor gene), it was found that the nomadic group was relatively healthier with higher BMIs and those who had settled fared worse. This research suggests the importance of environmental context and how genotypes in one setting may be advantageous while causing problems in other settings.
The argument follows that the strengths of children with ADHD traits are ‘mismatched’ to their current environments. A key tenet of evolution is that survival and success in different environments is predicated on genetic variations. Those who may be more suited to outdoor activities, more stimulating environments and more active learning approaches, may underperform and suffer in a conventional classroom setting where the emphasis is on quietness, attentiveness and compliance for extended periods of time. This is particularly relevant as unlike other mental disorders, ADHD diagnosed predominantly in the classroom in children between the ages of 6 and 12 (NHS Choices, 2016).
Learning Objective 3:
Describe the principle of ‘fast life history’ strategies and how this can help our understanding of ADHD
While the ‘environmental mismatch’ concept covered in Learning Objective 2 involves a phylogenetic approach to our development as a species, any comprehensive evolutionary synthesis of a mental disorder should also incorporate ontological issues, relating to individual life history and development. A ‘fast life history’ strategy is a behavioural syndrome generally taken to involve a pattern of above average levels of risk taking and novelty seeking arising from adolescence onwards. Such a strategy may be associated with a number of mental disorders including mood disorders, personality disorders and, especially if untreated, ADHD. Individuals adopting such a strategy may engage in sexual activity from an early age, along with other risky behaviours such as alcohol and drug use. Relationship patterns tend to be unstable and the individual may become increasingly conduct disordered and antisocial as they grow older with ultimate outcome measures such as the overrepresentation of ADHD in prison inmate populations. Furthermore, those adopting a fast life history strategy tend to have more children at a younger age in whom they invest less, leading to an intergenerational transmission of similar traits, possibly explaining recent higher prevalence (Swanepoel et al., 2017).
This ontological based knowledge of the multiple adverse outcomes associated with untreated ADHD should act as a powerful motivator for healthcare professionals, educators and family members to take a proactive and multifaceted approach to supporting children with ADHD from an early stage in an effort to optimise quality of life and functioning and to avoid potentially lifelong negative outcomes for the individual, their family and wider society. This is particularly salient for those children with ADHD who may lack family and adequate educational support and who have comorbid psychiatric disorders, intellectual disability or developmental delay. Indeed ADHD incurs a 17-fold greater economic burden due to increased needs in education, health and social care while also increasing the likelihood that children will be bullies or the victims of bullying (Verlinden et al., 2015).
Clinical Station 3: The School Visit
After the feedback meeting with Mark’s parents, you arrange to visit his school. You spend some time observing Mark in the classroom and in the yard at break-time. This confirms the accounts of his parents and his teacher: he tends to be restless, loud, impulsive and inattentive with schoolwork. Other children tend to avoid him in the school yard as he can be rough and clumsy.
After class you have a meeting with Mark’s teacher. ‘As I said to you before, he really is a lovely boy. But I don’t know if he’s ever going to settle down. Mrs. Molamphy is one of the older teachers here and she taught his father and uncles and she said they were just the same as Mark. Over time they settled a little but they were always better with outdoor activities than classroom-based lessons. Our student: teacher ratio is high in this school so we don’t always have the time to deal with boys like Mark. I don’t mean to seem like I’m pressuring you or putting words in your mouth, but if you can make a formal diagnosis of ADHD then Mark will be entitled to a Special Needs Assistant who will spend extra time with him in the classroom and take him out for exercise breaks during the day. Oh, and I know it’s entirely the call of his parents and you, but if he does have an ADHD diagnosis then medication should be considered. I’ve seen medication do wonders for boys like Mark’.
Clinical station 4: ‘So doctor, what’s the plan?’
Over the following week you incorporate the various pieces of information about Mark into his file, including your direct observations of him, the history provided by his parents, the Conners Rating Scales and his background developmental history.
You then arrange to meet with Mark’s parents again. They are very appreciative of the rigorous assessment to date. ‘We’re glad you didn’t jump straight in with medication’, says Mark’s father. ‘Although we know it might be needed’, adds his wife. Mark’s father goes on: ‘And we’ve spoken to Mark’s teacher. We know that the school has a role to play here too. And all the information you gave me about family history and children in modern environments, well that all makes sense to us’, he says, looking at his wife, who smiles back at him. ‘So, I’ve been thinking. With the nature of my music work I’m usually off during the day so I’m very happy to call in to the school daily and give him extra attention, take him out for exercise, anything that will help. Of course, I’ll do it in a formal, structured way’. Mark’s mother smiles at her husband and gently squeezes his hand. Then she leans forward slightly and faces you directly: ‘So doctor, what’s the plan?’
(See Learning Objective 4 below)
Learning Objective 4:
Outline how the evolutionary perspective can help inform individual treatment strategies for ADHD
As with any formulation and treatment plan informed by a comprehensive evolutionary and thus truly biopsychosocial perspective, the SOCIAL questions defined by Nesse (2018) are always a useful starting point.
As this is a child assessment, the questions will need to be modified but the usual principles apply, involving detailed description and documentation of Mark’s Social situation (i.e. level of contact and quality of relationship with friends), Occupation (in this case, the focus will be on his performance in school); Children and family (in the case of a child, the focus will be on the quality of relationships with parents and siblings); Income (in the case of a young child, the focus will be on issues such as family poverty or hardship), Abilities and appearance (this may relate to e.g. educational performance and performance in sports) and Love and sex (e.g. the quality of relationship with parents and siblings).
All of the information in this case can thus be classified under the above outlined SOCIAL system and such an approach is likely to lead to a more cohesive treatment plan than the standard biopsychosocial or medical model, while also being more attractive to family members, teachers and potentially even to the child himself.
As outlined in Learning Objective 3, lessons from life history theory and the association between ADHD and the adoption of fast life history strategies should highlight the importance of early, proactive and preventive intervention in ADHD and steer us away from the potentially complacent hope that, like his father and uncles in this case, Mark will just find a niche in life and do well as a result.
The ‘mismatch’ principle covered in Learning Objective 2 should lead us to broaden the discussion and treatment plan beyond the confines of medication prescribing, a blind, generic ‘behavioural programme’ and an assumption that the standard classroom setting is optimal for all children and unchangeable as it currently exists.
Considering all these factors, a practical and patient orientated approach to individual treatment should follow on from the above outlined SOCIAL assessment and consider first any modifiable non-medical and environmental measures that can be addressed.
Such a treatment plan is likely to comprise many layers, including parenting style and behaviour (e.g. a social reward-based system may be particularly attractive to children with ADHD) with due consideration paid to the fact that either or both parents may share genetic susceptibility for ADHD with their child and may thus need psychoeducation, parenting guidance and perhaps even treatment themselves.
School based evaluation and close working with teachers is also essential. A comprehensive exercise programme should be built into the child’s school day. ADHD affects predominantly male children and teaching staff are primarily female (Swanepoel et al, 2017). Therefore, access to a male teacher or Special Needs Assistant (SNA) who is more likely to facilitate the child in outdoor and sports-based activities and learning exercises may be particularly useful. An SNA may also have an important role in sitting with the child during some class-based activities and helping them to keep engaged with lessons with frequent feedback and reassurance.
Everyone involved in the treatment plan, including parents, teachers, SNAs and the child themselves should see their specific role and inputs in the context of the overarching plan and the plan should be reviewed regularly and adjusted as needed. Additionally, the evolutionary informed approach will not necessarily consider the child as ‘disordered’ but on the merit of their strengths and difficulties and the adaptive value. Shifting these perceptions will allow all involved in the care of the child to attempt to change the environment which is potentially more reversible than our genetics.
Should the child continue to struggle academically or behaviourally despite the above changes, then the case for medication prescribing (e.g. dopaminergic stimulants such as Methylphenidate) is altogether stronger and may have to be considered. However, even if a decision is made to use medication, it should only be in conjunction with a continuing strategy incorporating all possible environmental, family based and educational strategies and never as a replacement for these.
The evolutionary approach allows a more informed debate of changes in schools and education required in the long-term to best suit children with ADHD.
Learning Objective 5:
Outline how the evolutionary perspective can help inform research strategies for ADHD
The evolutionary perspective provides an essential underpinning framework for psychology and psychiatry. However, in order to avoid falling into the trap of formulating and believing ‘just so’ stories, the evolutionary perspective must be harnessed to generate testable hypotheses and research questions. The study by Eisenberg and colleagues (2008) thus addresses in part the question of ADHD traits and environmental mismatch, i.e. how a certain phenotype may be advantageous in one environment while having a negative impact in another. The evolutionary perspective helps generates multiple other potentially testable research questions, including questions around treatment strategies. Therefore, potentially useful research questions could be formulated in relation to the role of physical exercise in treating ADHD, the role of outdoor activities, the role of psychoeducation for parents and family members and the role of tailored career advice.
Additionally, further studies could confirm these predictions by for example testing foraging capabilities of those with ADHD and controls, elucidating mental and physical health differences between current nomadic individuals and settled controls and demonstrating a larger presence of ADHD and/or novelty-seeking traits in certain jobs requiring regular physical activity and rapid decision-making versus controls engaged in sedentary work involving longer timescales.
Modern day hunter gatherer groups can be used to confirm hypotheses in evolutionary psychiatry - thus arguing that modern day hunter gatherer societies may act as a natural laboratory to confirm /disconfirm the findings of evolutionary psychiatry/psychology. Further ethnographic studies in these populations could extend the evolutionary theories behind ADHD (Dein, 2015).
If you enjoyed this article and would like to discover more about Evolutionary Psychiatry please consider:
subscribing to our Substack to receive regular content updates
visiting the webpage of the Evolution and Psychiatry Special Interest Group within the College of Psychiatrists of Ireland
visiting the webpage of the Evolutionary Psychiatry Special Interest Group within the Royal College of Psychiatrists
exploring a Youtube playlist on curated presentations by the Evolution and Psychiatry Special Interest Group within the College of Psychiatrists of Ireland
exploring the Youtube page of the Evolutionary Psychiatry Special Interest Group within the Royal College of Psychiatrists
exploring the Evolving Psychiatry podcast