Fundamental Neurobiology of ADHD and ASD

“Everybody is talking about the weather, but nobody does anything about it!” – (Storm P.). It’s the same in regards to ADHD and ASD. Everyone thinks that they know all about it, but they really don’t! Let me guide you into the fascinating world of the Fundamental Biology of ADHD and ASD.


I hate not knowing how things relates to each other. Maybe it’s my autistic hyper-focusing or maybe it’s my relentless pursuit of my next Dopamine fix, caused by my ADHD (learning new knowledge, actually produces a reward of Dopamine in your Brain).. Nonetheless, I am going into a ‘death-roll spiral’ down the Rabbit Hole at the moment, primarily caused by the latest intellectual atrocities purposed by some in the USA that wishes to censor those who believe that vaccines causes Autism, so that their views are removed from both social media and Google Search.

Although I do not sympathize with the Anti-Vaxx Movement and their views, I’ve appalled that it is even suggested that their views should be censored – WTF!?!?

There is no valid reason for censoring a debate on any subject. Period. It reminds me of the Nazi Book Burnings or the Spanish Inquisition … Imagine if Gallileo wasn’t allowed to argue that the Earth was not flat, but in fact round … what kind of a world would we live in today, then? … Oh wait, they did do that, didn’t they? – AND HOW DID THAT WORK OUT FOR YOU!?

I like Truthstream Media, not because I agree with their opinions, cause I do not in large parts, but I respect them for their research work and their engagement, so let me share this brandnew video that they’ve just released, to allow you to get aquainted with the background story for this article.

1 hour Documentary oon the Anti-Vaccine debacle and freedom of speech

OK, let’s get started then …


As is the case with all new things, practice makes perfect. To get the full benefit of this article, I recommend that you spend the 9 minutes to watch this video, which explains the Human Nervous System, as I will be using a lot of medical terminology throughout this article.

Fundamentals of the Human Nervous System

The Human Nervous System is a very complex network of integrated parts, or systems, that in total makes up the ‘Central Command System’ of your body. It has developed over millions of years, as our species went through evolutionary changes to adapt to ever changing environmental factors. We share a lot of the features of our Nervous System with our species, but the human species have one distinct advantage, over all our species.

The Human Mind is capable of Hindsight and Foresight; looking back, to look ahead, to prepare for, what’s coming at you!

Dr. Russell A. Barkley, Ph.D. – World Renowned Neuropsychologist

What this entails, is that we humans can use our past experiences to try to predict future possible scenarios, while manipulating multiple simulated versions of predictions of outcomes, based on a ‘gut-feeling’ that guides our decision-making in the present tense.

This enables us to postpone immediate gratification of basic needs like hunger, sleep, safety and, of course, sex. By being able to NOT eat that marsmellow in front of you, when told that you will get TWO marshmellows, if you can manage to wait for 15 minutes, humans can use a vital core component within our Nervous System called Inhibition.

Inhibition is like your mother’s voice inside you head, constantly telling you; don’t do it!. Inhibition is what ensures that you don’t jump of that building to check if you’re able to fly or not. It is a key component of the success of the survival of our species.

But if all you’re hearing inside your head, is the warning to NOT do something, you will surely not survive for very long. Therefore the human body have created an extremely simple, but immensely versatile and powerful Reward System, which instructs you when to act out an idea and when not to. This Reward System is called the Dopaminergic System.

The Dopaminergic System is essential to all human behavior, as it guides the body to take actions, which the body finds beneficial for our well-being and survival. The key component of this function is a small molecule neurotransmitter named Dopamine (DA).

For more on Neurotransmitters, watch this

Dopamine is released into the Nervous System to regulate our behavior. When we take actions that our body believes is beneficial for us, we get a Dopamine reward in exchange. Think of a dog being taught to do a new trick, everytime it gets it right, it receives a reward to condition that behavior, so that it will be more likely to want to do more of that behavior.

But since Dopamine is used for a wide array of bodily functions and since the supply of Dopamine in the human body is limited, evolution have made a neat trick called Habituation.

This video illutrates how Habituation works, when training Police K9’s

Habituation in relation to Dopamine can be explained like this; the more you do something, the less dopamine you will receive as your reward. The reason for this, is that repeated actions quickly becomes automatic, meaning that they are being initiated and controlled by our unconscious mind. You now them well, we call the habits, in everyday life.

To understand how the Reward System works, watch this video

Habits are what guides our behavior. Humans are excellent at ‘repeating the same actions, over and over again, without paying attention’. The ‘without paying attention’ is the important part for the topic of this article, since both ADHD and ASD are closely related to inhibition and attention, which is the at the root of these neurodevelopmental disorders.

This video explains how NORMAL neurodevelopment works.

A neurodevelopmental disorder simply mean that it is a disorder of normal human development, from the creation of the embryo and up until the age of 25-30 years. The human brain comes with some basic survival skills, called instincts. The most prominent one is our self-preservation instinct, which guides us to always try to avoid getting killed, while still trying to get as much chance of procreating and raise our offspring, so that they can ensure the survival of our species, as a whole.

Since humans left the trees and began living on the African Savanna, we had to adapt to the new enviroment, by becoming bipedal – walking upright. This is turn created a problem for females, when giving birth, since the pelvic area of the female then became less flexible, which is essential for pressing a baby through the birth canal and out into the world.

To learn about human evolution, watch this video

To cope with this challenge, we have developed into being born with a smaller cranium that we had when we walked on all four, and therefore they size of the brain of a newborn baby, had to become smaller to. To make sure that we still could manage to survive in the hostile environment on the African Savanna, we became able to ‘grow our brain’ after birth. This ability is called Neuroplasticity.

Neuroplasticity well-explained in just 90 seconds

This ability to ‘rewire our brain’ as we develop into adulthood, is essential for successful human survival. You are born with certain basic instincts which will keep you alive (if your basic needs are met, of course), but these will not help you develop into an intelligent human being. This requires a whole lot of learning, repetition and reinforcement of behavior.

One of these important developmental stages is called ‘Gross Motor Development, which refers to the ability to control your body movements, crawl and finally walk. But this is just one part of the development of the Motor System in humans. Motor Control is the ability to consciously manage all of your verbal (language) and non-verbal (body movement) behvioral skills.

To understand how language develops, we need to understand that speaking is a motor function similar to that of moving your feets. Sounds is created by manipulating muscles in your throat (Larynx) which the travels up into your mouth where your lips form to make distinct sounds … also known as … words.

So not only does the baby need to master moving its body, it also have to learn how to control their speech and learn how to communicate needs to the outside environment (crying for mummy, banging the spoon on the plate etc,), but also to gradually develop the ability to ‘talk to themselves, within their own mind, without sound being released into the public environment. This is referred to as ‘Private Speech’ or ‘Inner Voice’.

This ability to ‘talk to yourself, without others knowing what you are saying’ is what we understand as – thinking to ourselves – This ability is essential for the management of internal and external, verbal and non-verbal, behaviors. These behaviors are what we use to inhibit our immediate needs, to postpone actions in the present tense, to gain a more attractive reward, in the future.

The same goes for developing your ‘Mind’s Eye’, your inner cinema screen on which to can ‘re-run’ past life experiences, also called – your memories – and these visual images is stored in our Long-term Memory, along with a whole host of sensory information which was ‘encoded’ when the ‘picture was taken’.

Imagine yourself as a child, maybe your first day of school. Try to remember as many details about that day, as you possible can. What was the weather like?, did you feel excited or anxious? What clothes did you wear? How did the school smell? How did the chair at your school-desk feel like to sit on? And how was the sound of your teacher’s voice, soft or harsh?

Memory Recall Exercise illustrting how the Mind works by association of stored sensory information (image, sound, taste, smell, touch etc.)

These ‘extra informations’ that are stored in your memory, along with the visual image of the that experience, are called Modalities. Today you may have heard about ‘Metadata’ being ‘encoded’ on the pictures your take one you phone. These metadata is things like date and time, location, light exposure in the moment the picture was taken, and maybe even some facial recognition of the people in the picture stored as metatags so that you can search for ‘Peter’ in your photo library and get all the pictures which the software believes to be pictures of Peter.

The brain works in a somewhat similar way, but with vastly more complexity (and functioning at an incredible speed, that no human made computer can even get close to matching today) and the ‘search algorithms’ are infinitely more complex than even those of Google Search.

It is possible to ‘recall’ a past experience (or actually you will be presented with an array of similar experiences (or memories) that all have som relation to the smell of ‘strawberry’, if your encounter that smell in the present tense.

Then your brain will try to pull all of your stored experiences with the smell of strawberries and ‘project’ those into your Executive Functions for analysis, simulation and decision-making process, on how to best proceed, when being subjected to the smell of strawberries. The is called Hindsight and Foresight.

This leads us back to the quote from Dr. Barkley which I stated, at the beginning of this article; The Human Mind is capable of Hindsight and Foresight; looking back, to look ahead, to prepare for, what’s coming at you!

Recap of biological fundamentals

So to recap all we have learned so far:

The Human Brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system (CNS). The brain consists of the cerebrum, the brainstem and the cerebellum.

The Human Central Nervous System

It controls most of the activities of the body, processing, integrating, and coordinating the information it receives from the sense organs, and making decisions as to the instructions sent to the rest of the body.

Easy way to remember the four lobes as a fisted hand

The brain is divided in to hemipheres, the right and the left. Each hemisphere is conventionally divided into four lobes – the frontaltemporalparietal, and occipital lobes:

  • The frontal lobe is associated with executive functions including self-controlplanningreasoning, and abstract thought.
  • The temporal lobe holds the primary auditory cortex, which is important for the processing of semantics in both speech and vision in humans.
  • The parietal lobe is where information such as taste, temperature and touch are integrated, or processed. Humans would not be able to to feel sensations of touch, if the parietal lobe was damaged.
  • The occipital lobe makes sense of visual information so that we are able to understand it. If our occipital lobe was impaired, or injured we would not be able to correctly process visual signals, thus visual confusion would result.
Illustrates how all of our organs are connected to the Brain
Illustrates how the sense of touch is relayed to the Brain

Illustrates how our senses are connected within the Brain

Illustrates how Afferent stimuli from the senses travels uo to the Brain and how Efferent Motor receives its instructions on the response should be released into verbal and/or non-verbal behavior.


Now we move into the unique world of fantasy, predictions, emotions and ideas … The Mind and the fascinating realm of neuropsychology, where the Mind, Brain and Body becomes .. YOU!

The Human Mind is not a thing, it’s a process!

Watch this to understand how the Human Mind works

The Mind is a complex system, which consists of a unimagineable vast network of neuronal networks, that is interconnected criss cross across the Brain and sometimes even extended into the Body.

Some neuronal network are specialized to handle specific proccesses, e.g. vision, hearing, smell etc. that handles the information that the Brain receives from the Body.

Others are more generalized or in their functioning, like our Executive Functions, which is located within the frontal lobe, but realies heavily on information from the Brain and the Body, in order to receive information, that it then analyses, interprets, predicts, simulate and finally decides on a response which is then send to the Brain for execution throughout the Body as verbal and/or non-verbal behavior.

Executive function can be broadly defined as a set of neurocognitive processes that allow for the organization of behavior across time so as to attain future goals.

Dr. Russell A. Barkley, Ph.D.

Executive Function (EF) is a set of mental skills that help you get things done. EF is comprised of 2 broad domains: inhibition and metacognition.

Inhibition encompasses the ability to inhibit motor, verbal, cognitive, and emotional activities. Metacognition, which include nonverbal working memory, verbal working memory, planning & problem-solving, and emotional self-regulation.

EF helps you:

  • Manage time
  • Pay attention
  • Switch focus
  • Plan and organize
  • Remember details
  • Avoid saying or doing the wrong thing
  • Do things based on your experience
  • Multitask

Summation of biology and neuropsychology

The Human Mind needs the Brain to access the outside world. The Mind lives with the Brain/Body system, and it is completely dependant on receiving information from, firstly the Body that sends information from the sensory system to the Brain, which then in turn ‘filters and interprets’ the information received, as well as prioritizing what the Brain can handle automatically and what needs to be forwarded to the Mind for further processing.

Since both the Mind and the Brain are dependant on the stimuli it receives from the Body, it cannot know of anything in the outside world, so that is why we ‘create our own reality’, which is basically our best guess of what’s happenning, based on previous experiences, sensory information and the use of complicated cognitive processes, Executive Functioning, to ‘guesstimate’ what the best response to the incoming stimuli would be, bearing in mind that we are going for the long-term benefit of maximizing our ‘return-on-energy-investment’ by postponing immediate gratification of our needs.

So to sum it all up;

‘Reality is an illusion and your Mind is playing tricks on you, every second of every minute of every day of your entire life, and that’s a good thing, since you would have died from exhaustion long ago, if you had to consciously making decision on everything going on, at any given moment in time’

Peter ‘ADDspeaker’ Vang (2019)


I hope that you have felt that this ‘short introduction’ has been worth while, and that you are now more ready to get down to the knots and bolts of what the heck ADHD and ASD – really is – and why that is so. I provided some additional ressources below, but have consciously opted not to put references to this massive amount of information from a wealth of sources, but I put my name and reputation on the line, stating that I have only used scientifically, peer-reviewed and published data, when writing this article.

/Peter ‘ADDspeaker’ Vang

Key Points to remember

  • As neurodevelopmental disorders, both ASD and ADHD share some phenotypic similarities, but are characterized by distinct diagnostic criteria.
  • ADHD and ASD are both heavily genetic in nature, with a heritability of 70-90% shared across probands (means that symptoms of ADHD and ASD are due to genetic factors, shared across familymembers) showing supporting evidence for the fact, that you cannot aquire ADHD or ASD from anything else than genetics.
  • 70% af all cases of ADHD are due to inherited genetic factors, the rest is due to neurobiological environmental factors during pregnancy (e.g. infections or pollution from heavy metals).
  • You cannot get neither ADHD or ASD later on in life, since this is a neurodevelopmental disorder, which implicitly makes it impossible to develop, once your brain is already fully developed, right?
  • You can, however, develop ADHD-like symptoms later in life, if you suffer a Traumatic Brain Injury (TBI), but it is NOT the same as being born with ADHD.
  • Treatments for ADHD is highly developed and the scientific consensus is that ADHD is optimally treated with a combined treatment with ADHD-medication and psychosocial support, at the same time.
  • Treatments for ASD is not currently (officially) supported by any medication, since it is a pervasive disorder (meaning that it messes up things all over the Brain, making it very hard to medicate effectively.

We, at ADDspeaker have many, many adult members who have ADHD with comorbid ASD (remember that between 30-50% af all with ASD, also suffers from ADHD, and 66% of people with ADHD, also suffers from ASD.
Our experience from real life usage of Guanfacine in combination with other ADHD-medication actually seems to alleviate some of the ASD symptoms that become both very visible and causing a higher degree of perceived impairment, since Guanfacine works on the Sympathetic Nervous System by lowering the blood pressure, and also by regulating the Alpha2-ports on synapses, which in turn ‘fine-tune’ or ‘boosts’ the effect of other ADHD-medication that works primarily in the frontal lobes.
The result is a reduction in sensory overstimulation, which in turn reduces the emotional dysregulation that is inherent in both ADHD and ASD.

Peter ‘ADDspeaker’ Vang is not a licensed psychiatrist, psychologist or have any other form of formal medical training, but he has researched and written about these subjects, since 2012 and hve a vast international network of scientists who have been generously sharing their research with him, to help better bring this scientific knowledge made available for the broader public. Always consult your doctor before making any changes to your medications!

Additional Ressources

Defining a neurodevelopmental disorder

Watch this to get an thorough introduction to neurodevelopmental disorders

Defining a specific vs. a pervasive neurodevelopmental disorder

A specific neurodevelopmental disorder primarily (but not exclusively) affect SOME part of cognitive functioning. A pervasive neurodevelopmental disorder affects ALL areas of cognitive functioning.

In turn, deficits in inhibition contribute to deficits in the development of 4 aspects of executive function in the domain of metacognition, which include nonverbal working memory, verbal working memory, planning and problem-solving, and emotional self-regulation.

ADHD vs. Autism

ADHD and Autism are neurodevelopmental disorders that impact similar brain functions. They are different conditions, but they share some of the same symptomsdifficulty settling down, social awkwardness, the ability to focus only on things that interest them, and impulsivity — and a common genetic link.

Neuroanatomy and Neuropathology of Autism Spectrum Disorder in Humans
Illustration of the neuro-typical (normal) development of the Brain

What happens when an embryo is created, and its DNA have been determined, all the genes that’s in that DNA, is that those genes have the potential to get activated in the feetus during pregnancy and sometimes due to epigenetic factors after birth.

Genes are like flicking a light switch. If their switch is NOT ‘flung’ at embryo creation, the gene’s RNA will not begin to copy that gene, unless some external factor activates them, later on. This is a the core of the whole anti-vaccine vs. autism debacle going on, since science have tried, without much luck sadly, to explain that those children who unfortunately develop Regressive Brain Disease after being vaccinated, have to have the RBD genes present in their DNA, in order for them to develop autism-like symptoms. That is why vaccines cannot cause autism, since it is dependant on the RBD disease genes being their already. It is exactly the same as with Anxiety, Diabetes Type-II, and many, many other genetically inheritable diseases and disorders.

Understanding the ways in which deficits in executive function contribute to the symptoms of ADHD can help in differentiating ADHD from disorders that share similar characteristics.

Great ressource for in-depth information can be found here:

Autism Spectrum Disorder

Diagnostic definition of Autisme Spectrum Disorder from the latest version of ICD. ICD-11 which will be implemented in 2022, describes ASD as follows:
“Autism spectrum disorder is characterized by persistent deficits in the ability to initiate and to sustain reciprocal social interaction and social communication, and by a range of restricted, repetitive, and inflexible patterns of behaviour and interests. The onset of the disorder occurs during the developmental period, typically in early childhood, but symptoms may not become fully manifest until later, when social demands exceed limited capacities. Deficits are sufficiently severe to cause impairment in personal, family, social, educational, occupational or other important areas of functioning and are usually a pervasive feature of the individual’s functioning observable in all settings, although they may vary according to social, educational, or other context. Individuals along the spectrum exhibit a full range of intellectual functioning and language abilities.

Autism is a complex neurobiological disorder that affects boys four times as often as girls. Autistic spectrum disorders (ASD) are usually called Pervasive Developmental Disorders (PDD) by physicians.

PDD is a group of three conditions — autistic disorder, Asperger syndrome, and Pervasive Development Disorder Not Otherwise Specified.

The conditions are characterized by problems communicating and relating to others, and a need to follow rigid routines and to engage in repetitive behaviors or language.

ASD is a lifelong, heterogeneous neurodevelopmental condition characterised by deficits in social communication and repetitive and restricted behaviours (including sensory anomalies).

The aetiological and neurobiological mechanisms underlying ASD are complex, and there is considerable heterogeneity in the clinical and neurobiological phenotype among individuals on the autism spectrum. However, research agrees that ASD is accompanied by differences in brain anatomy and connectivity.

Neurobiological causation of ASD

ASDs are recognized to be brain-based neurodevelopmental disorders, with differences emerging early in childhood.

However, as is the case for genes, no universal neurofunctional or neuroanatomical abnormality has been discovered; as is also the case for genes, this, in part, likely reflects heterogeneity in etiological and developmental course.

Cytological studies of brain structure have revealed reduced neuronal size and increased cell-packing density in the hippocampus, amygdala, mammillary body, anterior cingulate cortex, and septum.

Furthermore, decreased numbers of Purkinje cells and granule cells in the cerebellum have been described (Minshew et al., 2005).

Multiple structural brain studies have also revealed abnormalities in cerebellar regions, but specific areas affected have varied between studies.

Several studies have also indicated reduction in the connective tract of the corpus callosum (Minshew et al., 2005). A combination of early-childhood pediatric data and subsequently collected magnetic resonance imaging data suggest that a significant portion of children with ASD exhibit increased atypical development of brain volume, with temporal lobe white matter showing overgrowth during the second year of life despite typical size at birth (Courchesne et al., 2001; Hazlett et al., 2005).

Studies of neurochemistry have revealed various atypicalities in individuals with ASD, though elevated blood serotonin levels have been reported with the greatest frequency.

Other findings have included abnormal pep- tide excretion, neuroendocrine/hypothalamic–pituitary–adrenal function, amino acid levels, uric acid excretion, and central cholinergic and GABAergic receptors (Anderson and Hoshino, 2005).

A current topic of great interest is the role of oxytocin and vasopressin in autistic neuropathology. Because of their role in prosocial behavior and social bonding (Lim and Young, 2006), these neuropeptides have long been speculated to be involved in autistic social dysfunction (Modahl et al., 1992).

Oxytocin has been shown to increase eye gaze in typical individuals (Guastella et al., 2008), and a recent study found that administration of intranasal oxytocin improved emotion recognition in adolescents with ASD (Guastella et al., 2010).

Variation in the oxytocin receptor gene has been associated with ASD in some populations (Wermter et al., 2010), but current evidence suggests this is not true for all groups (Tansey et al., 2010).

Functional brain imaging studies have also revealed a variety of atypicalities without an emergent universal pattern. Rates of seizure are increased in children with ASD, and electroencephalographic recordings (EEGs) reveal an increased incidence of anomalous EEG in children with ASD, even among those without seizure disorder, most notably among individuals with significant cognitive impairment (Minshew et al., 2005).

Following from the aforementioned social brain theories of ASD, numerous functional magnetic resonance imaging (fMRI) and event-related potential
studies of hemodynamic and electrophysiological brain responses suggest anomalous functioning of brain regions subserving the processing of social information (Dawson et al., 2005; Schultz, 2005).

Affected brain systems have been posited to include: face perception, linked to the fusiform gyrus (Puce et al., 1996; Kanwisher et al., 1997); biological motion perception, linked to the superior temporal sulcus (Pelphrey et al., 2003); the action perception system, linked to the inferior frontal gyrus and inferior parietal lobe (Iacoboni et al., 1999; Rizzolatti and Craighero, 2004); perception of emotional states and emotional experience, linked to the amygdala and limbic system (LeDoux, 1994; Adolphs et al., 1995); visual perception of the human body, linked to the extrastriate body area in lateral occipitotemporal cortex (Downing et al., 2001); social reward and reinforcement, linked to the orbitofrontal cortex (Bechara et al., 1994; Cools et al., 2002); and theory of mind, linked to the ventromedial prefrontal cortex (Castelli et al., 2002).

An additional body of research, paralleling psychological theories of impaired processing of complex or global information, has investigated connectivity in the brains of individuals with autism.

Several studies have directly measured connectivity through imaging of white-matter tracts connecting different brain regions, demonstrating atypical patterns of connective tissue in ASD (Barnea-Goraly et al., 2004; Herbert et al., 2004; Keller et al., 2007); however, most evidence for atypical interconnectivity in ASD has relied on fMRI to examine covariation in activity in distal brain regions.

This approach has demonstrated atypical connectivity at rest (Cherkassky et al., 2006; Di Martino et al., 2009) and during a wide range of tasks, including face perception (Welchew et al., 2005; Bird et al., 2006; Kleinhans et al., 2008; Koshino et al., 2008), attribution of mental states during viewing of animations (Castelli et al., 2002; Kana et al., 2008), language processing (Just et al., 2004; Kana et al., 2006), executive function (Koshino et al., 2005; Just et al., 2007), visual-motor action (Villalobos et al., 2005; Mizuno et al., 2006; Turner et al., 2006), and response inhibition (Kana et al., 2007).

This body of research reveals inconsistent patterns of results across studies, including underconnectivity, overconnectivity, and typical patterns of connectivity, suggesting that connectivity problems may not be a universal feature of ASD (Kleinhans et al., 2008).

Psychological theories of ASD

Two prevailing classes of theories attribute autistic impairments to:
(1) core impairment in social functioning and dysfunction in corresponding brain systems (Dawson et al., 2005); and
(2) dysfunctional processing of information that is complex or requires perception or manipulation at the gestalt level.

Social accounts of ASD posit that specific human brain systems exist to process information pertaining to other humans (Brothers, 1990), and autistic dysfunction originates in these brain systems, exerting secondary, peripheral impacts through developmental effects.

For example, the social motivation hypothesis posits that reduced social drive leads to inattention to people and consequent failure of developmental specialization in experience-driven brain systems, such as the face perception system (Dawson et al., 2005).

Within the class of social brain theories, the “theory of mind” account suggests specific difficulty with attribution of mental states to others; a criticism of this conceptualization has been that it fails to account for the earliest emerging and most developmentally basic symptoms of ASD.

Interconnectivity theories of ASD have taken several forms. The “weak central coherence” account posits a lack of a central drive for coherence, with the consequent focus on dissociated fragments rather than integrated “wholes,” leading to a fragmentary and overly concrete experience of the world.

Another hypothesis posits deficits in “executive functioning,” i.e., in the capacity to abstract rules, inhibit irrelevant responses, shift attention, and, generally, to “multitask.”

A commonality among these theories is that, in contrast to social information- processing theories, they generally cite nonspecific brain processes in which the nature of the information processed is relevant only insofar as it requires distributed brain function (Horwitz et al., 1988; Just et al., 2004). For example, it has been posited that, due to poor long-range connectivity, simple, local processing is intact while complex, distributed information processing is impaired in ASD (Minshew and Williams, 2007).

Because social interaction tends to be complex, these theories suggest that it is particularly vulnerable to disruption.


Attention-deficit hyperactivity disorder (ADHD) is the current term for a specific neurodevelopmental disorder seen in both children and adults that is comprised of deficits in behavioral inhibition, sustained attention and resistance to distraction, and the regulation of one’s activity level to the demands of a situation (hyperactivity or restlessness). The ratio between sexes are 4:1 in childhood, but more close to 1:1 by adulthood.

Diagnostic definition of Attention Deficit Hyperactivity Disorder (ADHD) from the latest version of ICD. ICD-11 which will be implemented in 2022, describes ASD as follows:
Attention deficit hyperactivity disorder is characterized by a persistent pattern (at least 6 months) of inattention and/or hyperactivity-impulsivity, with onset during the developmental period, typically early to mid-childhood. The degree of inattention and hyperactivity-impulsivity is outside the limits of normal variation expected for age and level of intellectual functioning and significantly interferes with academic, occupational, or social functioning. Inattention refers to significant difficulty in sustaining attention to tasks that do not provide a high level of stimulation or frequent rewards, distractibility and problems with organization. Hyperactivity refers to excessive motor activity and difficulties with remaining still, most evident in structured situations that require behavioural self-control. Impulsivity is a tendency to act in response to immediate stimuli, without deliberation or consideration of the risks and consequences. The relative balance and the specific manifestations of inattentive and hyperactive-impulsive characteristics varies across individuals, and may change over the course of development. In order for a diagnosis of disorder the behaviour pattern must be clearly observable in more than one setting.

Psychological theories of ADHD

The predominant features of this disorder include:

  1. Impaired response inhibition, impulse control, or the capacity to delay gratification. This is often noted in the individual’s inability to stop and think before acting; to wait one’s turn while playing games, conversing with others, or having to wait in line; to interrupt their responding quickly when it becomes evident that their actions are no longer effective; to resist distractions while concentrating or working; to work for larger, longer-term rewards rather than opting for smaller, more immediate ones; and inhibiting the dominant or immediate reaction to an event, as the situation may demand.
  2. Excessive task-irrelevant activity or activity that is poorly regulated to the demands of a situation. Individuals with ADHD in many cases are noted to be excessively fidgety, restless, and “on the go”. They display excessive movement not required to complete a task, such as wriggling their feet and legs, tapping things, rocking while seated, or shifting their posture or position while performing relatively boring tasks. Younger children with the disorder may show excessive running, climbing, and other gross motor activity. While this tends to decline with age, even teenagers with ADHD are more restless and fidgety than their peers. In adults with the disorder, this restlessness may be more subjective than outwardly observable, although with some adults they remain outwardly restless as well and report a new to always be busy or doing something and being unable to sit still.
  3. Poor sustained attention or persistence of effort to tasks. This problem often arises when the individual is assigned boring, tedious, protracted, or repetitive activities that lack intrinsic appeal to the person. They often fail to show the same level of persistence, “stick-to-it-tiveness,” motivation, and will-power of others their age when uninteresting yet important tasks must be performed. They often report becoming easily bored with such tasks and consequently shift from one uncompleted activity to another without completing these activities. Loss of concentration during tedious, boring, or protracted tasks is commonplace, as is an inability to return to their task on which they were working should they be unexpectedly interrupted. Thus, they are easily distracted during periods when concentration is important to the task at hand. They may also have problems with completing routine assignments without direct supervision, being unable to stay on task during independent work.

These are the three most common areas of difficulty associated with ADHD. However, research is suggesting that those with ADHD, particularly the subtypes associated with impulsive behavior (see below), may also have difficulties in the following areas of psychological functioning as well:

  1. Remembering to do things, or working memory. Working memory refers to the capacity to hold information in mind that will be used to guide one’s actions, either now, or at a later time. It is essential for remembering to do things in the near future. Those with ADHD often have difficulties with working memory and so are described as forgetful around doing things, unable to keep important information in mind that they will need to guide their actions later, and disorganized in their thinking and other activities as they often lose track of the goal of their activities. They may often be described as acting without hindsight or forethought, and being less able to anticipate and prepare for future events as well as others, all of which seem to be dependent on working memory. Recently, research suggests that those with ADHD cannot sense or use time as adequately as others in their daily activities, such that they are often late for appointments and deadlines, ill-prepared for upcoming activities, and less able to pursue long-term goals and plans as well as others. Problems with time management and organizing themselves for upcoming events are commonplace in older children and adults with the disorder.
  1. Delayed development of internal language (the mind’s voice) and rule-following. Research has lately been suggesting that children with ADHD are significantly delayed in the development of internal language, the private voice inside one’s mind that we employ to converse with ourselves, contemplate events, and direct or command our own behavior. This private speech is absolutely essential to the normal development of contemplation, reflection, and self-regulation. Its delay in those with ADHD contributes to significant problems with their ability to follow through on rules and instructions, to read and follow directions carefully, to follow through on their own plans, rules, and “do- lists,” and even to act with legal or moral principles in mind. When combined with their difficulties with working memory, this problem with self-talk or private speech often results in significant interference with reading comprehension, especially of complex, uninteresting, or extended reading assignments.
  2. Difficulties with regulation of emotions, motivation, and arousal. Children and adults with ADHD often have problems inhibiting their emotional reactions to events as well as do others of their age. It is not that the emotions they experience are inappropriate, but that those with ADHD are more likely to publicly manifest the emotions they experience than would someone else. They seem less able to internalize” their feelings, to keep them to themselves, and even to moderate them when they do so as others might do. Consequently, they are likely to appear to others as less emotionally mature, more reactive with their feelings, and more hot-headed, quick-tempered, and easily frustrated by events. Coupled with this problem with emotion regulation is the difficulty they have in generating intrinsic motivation for tasks that have no immediate payoff or appeal to them. This capacity to create private motivation, drive, or determination often makes them appear to lack will-power or self-discipline as they cannot stay with things that do not provide immediate reward, stimulation, or interest to them. Their motivation remains dependent on the immediate environment for how hard and how long they will work, whereas others develop a capacity for intrinsically motivating themselves in the absence of immediate rewards or other consequences. Also related to these difficulties with regulating emotion and motivation is that of regulating their general level of arousal to meet situational demands. Those with ADHD find it difficult to activate or arouse themselves to initiate work that must be done, often complain of being unable to stay alert or even awake in boring situations, and frequently seem to be daydreamy or “in a fog” when they should be more alert, focused, and actively engaged in a task.
  3. Diminished problem-solving ability, ingenuity, and flexibility in pursuing long-term goals. Often times, when we are engaged in goal-directed activities, problems are encountered that are obstacles to the goal’s attainment. At these times, individuals must be capable of quickly generating a variety of options to themselves, considering their respective outcomes, and selecting among them those which seem most likely to surmount the obstacle so they can continue toward their goal. Persons with ADHD find such hurdles to their goals to be more difficult to surmount; often giving up their goals in the face of obstacles and not taking the time to think through other options that could help them succeed toward their goal. Thus they may appear as less flexible in approaching problem situations, more likely to respond automatically or on impulse, and so are less creative at overcoming the road-blocks to their goals than others are likely to be. These problems may even be evident in the speech and writing of those with the disorder, as they are less able to quickly assemble their ideas into a more organized, coherent explanation of their thoughts. And so they are less able to rapidly assemble their actions or ideas into a chain of responses that effectively accomplishes the goal given them, be it verbal or behavioral in nature.
  4. Greater than normal variability in their task or work performance. It is typical of those with ADHD, especially those subtypes associated with impulsive behavior, to show substantial variability across time in the performance of their work. These wide swings may be found in the quality, quantity, and even speed of their work, failing to maintain a relatively even pattern of productivity and accuracy in their work from moment to moment and day to day. Such variability is often puzzling to others who witness it as it is clear that at some times, the person with ADHD can complete their work quickly and correctly while at others times, their tasks are performed poorly, inaccurately, and quite erratically. Indeed, some researchers see this pattern of high variability in work-related activities to be as much a hallmark of the disorder as is the poor inhibition and inattention described above.