134 Neurodiversity

Learning Objectives

By the end of this section, you will be able to:

  • Describe traits currently used in the diagnosis of ADHD and autism, as well as other traits, strengths, and barriers common to people in these populations
  • Identify possible causes and factors underlying behavioural and neurological differences associated with ADHD and autism
  • Identify supports commonly used to help overcome barriers affecting those with ADHD and autism
  • Compare and contrast sensory processing similarities and differences between autism and ADHD
In most introductory psychology texts, including the first edition of this one, this section is entitled ‘Neurodevelopmental Disorders’. This terminology presents atypical brain organization and development as disordered. All brains differ to some degree, so neurodivergence is a normal variation in the structure and function of a nervous system, even if it’s less common (Chappel & Worsley, 2021). Instead, this chapter will use the term neurodiversity, which was coined by autistic sociologist Judy Singer to acknowledge the diversity of neurotypes (different kinds of brain organization and function) that can appear in a population of healthy people. Your neurotype is present from birth to the end of your life, influencing development, cognition, sensory perception, emotional and behavioural regulation, and social behaviour, so it’s a fundamental part of who you are, guiding and informing your experience of the world. In this view, people who fall within the average range of neurotypes are neurotypical (NT), and people who exist outside of it are neurodivergent (Baumer & Frueh, 2021).  In fact, the term ‘neurotypical’ doesn’t refer to a specific neurotype, since there’s a lot of variation between the brains of neurotypical people as well. Differences in function that result from a person’s neurotype can change over time, and some people may not be identified as neurodiverse until adulthood. This section will focus on autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD), but dyslexia, dyscalculia, Down syndrome, hyperlexia, dyspraxia, Meares-Irlen Syndrome and Tourette Syndrome are often also considered to be types of neurodivergence as well.

Dig Deeper

Discussing Disability and Neurodivergence

The shift from ‘neurodevelopmental disorders’ to ‘neurodiversity’ reflects a change in the way we understand disability and neurodivergence. Historically, the medical model was used to define disability as defects in disabled people that should be cured or prevented (Hogan, 2019). Following this logic, poor outcomes like low employment and educational attainment are a result of disabled people’s limitations, and systemic factors that make these goals unattainable for them aren’t addressed. This means that under the medical model, disabled people are expected to overcome barriers related to disability, even if those barriers could be eliminated by making changes at a social level so that a wider variety of needs are considered. This model values the prevention of disability over the rights and wellbeing of disabled people and has even been used to argue for the prevention or ‘curing’ of things like same-gender attraction, which are not disabilities. Even in Canada, some provinces continued to classify homosexuality as a medical disorder until 2010 (CBC News, 2010).

An alternative promoted by many disabled people is the social model, which argues that disability mostly happens when systemic social factors disadvantage people with certain types of bodies and brains (Hogan, 2019; World Health Organization, 2022). Consider a person with colour deficiency trying to read a map. If the map uses colours affected by their colour deficiency, they may not be able to see the borders between countries, making the map useless to them. This person isn’t limited in their ability to understand maps, they are disadvantaged because their needs weren’t considered when the map was made. The social model isn’t meant to replace medical treatment when it’s needed, its primary goal is to improve and protect the rights of disabled people, which includes making treatment and accommodations more accessible (Guevara, 2021).

A related change involves ‘person first language’ (e.g., “a person with autism”), which is intended to reduce stigma by separating the condition from the person (Baumer & Frueh, 2021). This sometimes conflicts with language used by neurodivergent people; for example, many autistic people prefer identity-first language (e.g., “Autistic person”). This is meant to acknowledge that autism is a fundamental part of an autistic person, and that respecting personhood shouldn’t require the separation of a person from their neurotype (Kenny, 2015; Brown, 2011). However, not all neurodiverse people prefer identity-first language and in this text, we wish to respect differences in language preferences within these communities, with the understanding that discussions are ongoing. In this section, a mix of identity first and person first language will be used in order to acknowledge the lack of consensus and to respect both positions that may be held by neurodiverse people.

Attention-Deficit/Hyperactivity Disorder

Consider the following scenarios:

Samar is writing a quiz in class. He studied for it, but he has trouble holding attention long enough to follow along with lectures, so he listened over the recording several times to review. He’s proud of himself for keeping track of the quiz date and prepping in time, as he has trouble managing and remembering dates, and has missed important dates in the past. Samar speeds through it, feeling confident. Later he realizes he may have misread the instructions and missed a question. Despite studying and understanding the material, Samar doesn’t get the mark he hoped for. He goes to office hours, but he misplaced his quiz and the professor gets frustrated with him for losing focus when she is speaking to him. Outside of class, Samar struggles to connect with others because he loses track of conversations and often feels out of the loop. Samar may have primarily inattentive attention-deficit-hyperactivity-disorder (ADHD-PI).

Alaiya is writing a quiz in class. She can’t help tapping her feet and pencil, and she nearly stands up to pace, but she knows she’ll get in trouble for doing that. She tried to study, but she was jittery, and she couldn’t focus. The feeling made her so anxious that she gave up and played video games to calm down, though she didn’t mean to. She tried to join a study group, but she had trouble following the flow of conversation, blurting things out before others had finished talking. She left the group embarrassed and worried that they thought she was rude. Despite her effort, Aliya is discouraged when she gets her mark back. She goes to office hours, but there’s a line and she only manages to wait in it for a few minutes before she feels stressed and under stimulated and has to leave. Alaiya may have primarily hyperactive-impulsive ADHD (ADHD-HI).

As demonstrated above, ADHD presents in many ways. People like Samar mainly experience inattentive-type symptoms, having difficulty with sustained attention and tasks involving working memory. Others like Alaiya have more hyperactive-impulsive-type symptoms, meaning they’re motivated to seek stimulation and struggle with self-control. Others present with a combination of inattentive and hyperactive-impulsive traits (ADHD-C). Interestingly, the proportion of people with ADHD-PI increases with age, while the proportion with ADHD-HI decreases. For example, 23% of preschool age children with ADHD are primarily inattentive, but this percentage rises 75% in high school. In contrast, about 5% of preschool children are primarily hyperactive, and by high school only about 1.1% of people with ADHD are primarily inattentive. (de la Peña, 2020; Willcutt, 2012). This makes sense, since impulse control and sustained attention rely on brain systems that are still developing at this age, even for neurotypical children.

Symptoms and Traits

There are many ways that ADHD can present, so it’s likely that it represents a number of neurotypes with similar features. Since ADHD is neurodevelopmental, these traits are present since early childhood and exist across different settings. It’s also important to remember that some of the behavioural issues seen in people with ADHD are also seen in people experiencing trauma, sleep disorders, sensory processing disorders, and autism spectrum disorder. Some of these conditions can also coexist with ADHD. (Wolraich et al., 2019). The criteria currently used to diagnose ADHD come from the DSM-5, and involve inattentiveness, hyperactivity and impulsivity.


Inattentive symptoms involve difficulty keeping attention, so people with these symptoms often struggle to complete tasks, follow instructions, and use organizational skills. They may also have trouble holding attention for play or leisure activities, and may feel easily distracted (APA, 2013). Like Samar with his professor, people with these kinds of symptoms may have trouble maintaining attention in conversation or during interaction and are sometimes misunderstood as being distracted or withdrawn by others. As a result of these difficulties, they may struggle with self-esteem and social interaction, and may be reluctant to do things that require sustained attention. Some of these symptoms appear to be related to differences in sensory processing and may mean that people with these symptoms need more time to register and respond to stimuli (de la Peña, 2020).

Hyperactivity and Impulsivity

People with hyperactive and impulsive symptoms may have trouble being still. For example, children with ADHD may have trouble remaining seated when it’s expected for them to do so and may have a tendency to run or climb in inappropriate situations. For teens and adults with ADHD, this is commonly experienced as an intense discomfort and restlessness, even if they can suppress the urge to move. People with these symptoms may have trouble waiting their turn in conversation, and unintentionally interrupt others. As with inattentive symptoms, people with hyperactive-impulsive symptoms may have trouble engaging in play and leisure activities in the same way that neurotypical people do, and they may feel or appear to be constantly on the go (APA, 2013). Like Aliyah in her study group, people with these traits are sometimes misunderstood by others, and can experience social difficulties as a result.

Common Traits and Experiences

ADHD and Executive Function

Executive functions are skills that allow us to direct attention, focus, plan, control our behaviour, and regulate emotions (Diamond, 2012). Executive dysfunction occurs when those skills are impaired, resulting in difficulty with time management, impulse control, and emotional regulation. Many people with ADHD experience significant impairment relating to executive function (Silverstein et al., 2018). A specific executive function associated with ADHD is working memory (WM; sometimes used interchangeably with short-term memory). This is the component of memory that allows us to hold information in mind so we can work with it in the moment. Many people with ADHD have a lower WM capacity and have more difficulty manipulating information in WM (Martinussen et al., 2005).

Given the range of skills involved in executive function, it’s not surprising that executive dysfunction could contribute to many impairments that people with ADHD experience. It isn’t yet known if executive dysfunction is a core feature of ADHD, but some studies found that executive function abilities in early childhood can predict ADHD symptoms later in life (Sjöwall et al., 2015; Brocki et al. 2009), and many people with ADHD score differently than neurotypical people on certain executive function skills (Fan & Wang, 2022). There is evidence that parts of the frontal and parietal lobes involved in executive function processes are less active in people with ADHD (Faraone et al., 2015), Further evidence can be found in people with ADHD who respond well to stimulant medication, since they’re more likely than non-responders to show reduced activity in frontal lobe areas involved in executive functions (Ogrim & Kroptov, 2019). These differences in brain activity and response to stimulants help to explain the range of ways ADHD can present.

ADHD and Attention

The name itself implies that ADHD is a lack of attention, but this isn’t totally accurate. Instead, the brains of people with ADHD have trouble directing attention the way neurotypical brains do, so they do more local processing, or processing of individual details that make up a big picture rather than processing the picture as a whole (Song & Hakoda, 2012), which is called global processing (Figure PY. 10). As a result, someone taking a test may focus on a single multiple-choice option without reading the question itself as a whole, as Samar did. Samar had trouble focusing his attention on the expected parts of the test, and he also had trouble shifting his attention to more relevant information.

Local and global processing skills can be tested using a Compound Digit Cancelation Test (Figure PY.10). In this test, Digits are arranged spatially to make up larger compound digits. Digits making up compound digits require local processing, since they can be processed as individual details. The compound digits require global processing, since the subject must combine local features to understand them. In this example, the subject was told to cross out twos and eights, whether they appeared at the local or global level. They correctly selected the two made of eights, the six made of twos, and the eight made of twos, but they missed the eight made of sevens, indicating that they may be better at local than global processing, since they more frequently identified twos and eights at the local level.

Two rows of four numbers. In all cases, the numbers themselves are made up of smaller numbers. On the top row the numbers presented are 2 (created out of 8's), 6 (created out of 5's), 3 (created out of 9's), and 6 (created out of 2's). The first and last numbers are crossed out.
Figure PY.10 An example of a Compound Digit Cancellation Test (CDCT), used to assess global and local processing abilities. Digits are arranged spatially to make up larger compound digits. For example, a series of two’s lined up in the shape of a six. (credit: original work, Max Dysart)

An interesting result of this difference in attention is hyperfocus, a state of increased attention and motivation directed towards a particular subject. Hyperfocus is also reported by neurotypical people, but it’s more common in autistic people and those with ADHD (Groen et al., 2020).  People experiencing hyperfocus often lose their sense of time and ignore other stimuli, including bodily needs, because they can’t disengage. Hyperfocus can be a negative experience when focused on subjects that cause anxiety or which interfere with function, but it can also be enjoyable, resulting in increased productivity if focused on tasks that are beneficial to the individual (Hupfeld, 2018).


Image shows two sets of drawings of 'alien fruit'. The drawings on the left side are by non-ADHD individuals and look similar to regular fruit. The drawings on the right, by the ADHD group are much more atypical and unique.
Figure PY. 11 When asked to design and describe ‘alien fruit’, participants with ADHD (on the right) designed fruit that were rated as more original and had more atypical features than participants without ADHD (on the left). (credit: White, 2018)
Strengths for People with ADHD

Like other kinds of neurodivergence, ADHD involves both impairments and special skills less common in neurotypical people. One strength for people with ADHD is creativity, a skill that is enhanced by the ability to combine information in new and unexpected ways. People with ADHD on average display more flexible thinking than neurotypical people on word association tasks (White & Shah, 2016), and are less restricted by existing knowledge during drawing tasks, resulting in more original creations (Figure PY.11; White, 2018). Traits like impulsivity and difficulty ignoring ‘irrelevant’ stimuli, both associated with ADHD, are also more common in people who display high levels of creativity (Zabelina et al., 2015, Zabelina et al., 2013), so there may be common features in the neurobiology of ADHD and creativity. Beyond creativity, ADHD adults identified higher levels of energy, courage, adventurousness, and non-conformity as positive factors they associate with their ADHD (Holthe & Langvik, 2017, Sedgwick et al., 2018). There is also a higher-than-average rate of ADHD in populations of athletes, suggesting that some aspects of this neurotype support athletic engagement, like quick decision making and high energy (Han, 2019). In fact, Olympic athletes Simone Biles, Michael Phelps, and Molly Seidel all have ADHD. Other Icons with ADHD include musicians Solange Knowles, Henry Lau and engineer Dean Kamen, who invented the Segway and iBOT (Figure PY.12).


Series of four photographs as described in caption
Figure PY.12 (a) Solange Knowles performing at Coachella in 2014 (Adapted from work by Neon Tommy, licensed under CC BY 2.0) (b) Henry Lau at the 2020 Korea First Brand Awards ceremony (Adapted from work by NewsInstar, licensed under CC BY 3.0) (c) Dean Kamen speaking at the FIRST robotics world championship in 2012 (Adapted from work by Greg Heartsfield, licensed under CC BY 2.0) (d) Simone Biles with a gold medal at the 2016 olympics (Adapted from work by Agência Brasil Fotografias, licensed under CC BY 2.0)

Causes of ADHD

Given that ADHD can present in a variety of ways, it makes sense that there are a variety of contributing factors. It appears that ADHD is about 74% heritable, with many genes making small contributions, but environmental factors can also have an influence. For example, ADHD is more likely in those born premature, and those with early childhood infection. This may be because premature birth and infection cause inflammation, which alters neuron and synapse development. Many of the genes associated with ADHD are also involved in the growth and activity of neurons and synapses, especially those that use the neurotransmitters dopamine and norepinephrine. Indeed, the most common drug therapies for ADHD are stimulants like methylphenidate, which target dopamine and norepinephrine systems (Nùñez-Jaramillo et al., 2021).

Stimulants were first prescribed in the 1930’s to treat headaches, but they were more effective for helping some people to concentrate. Later, researchers discovered that stimulant medications increased dopamine activity in certain areas, so they started studying dopamine systems in people with ADHD (Lange et al., 2010). Now we know that some people with ADHD have less dopamine activity in the basal ganglia, the frontal lobes, and the circuits that connect the two. Working together these areas are involved in motivation, guiding attention and impulse control using dopamine as a messenger, so this pattern is more associated with attentional and hyperactive traits (Chu et al., 2021) than with inattentive traits. Other people with ADHD have higher than average connectivity between the prefrontal cortex and a subcortical area called the basal ganglia. This area is involved in perceptions of reward, and heightened connectivity here is associated with more impulsivity (Nùñez-Jaramillo et al., 2021).

Treatment and Support

Because there are a variety of factors that can result in the development of ADHD, treatments must be personalized. As we learned earlier, people with ADHD who have less frontal lobe activity respond better to treatment with stimulants, with reduced hyperactivity, impulsivity, and inattention. Commonly prescribed stimulants are amphetamine and related drugs including methylphenidate, which blocks reuptake dopamine and norepinephrine to increase their levels in the synapse; and atomoxetine, which only blocks reuptake of norepinephrine. This increased activity of dopamine supports increased activity in the frontal areas that are less active in some people with ADHD (Nùñez-Jaramillo et al., 2021). However, these drugs aren’t effective for everyone, and people taking them usually need other kinds of support.

There are also effective non-pharmacological therapies for people with ADHD, which aim to teach families and people with ADHD to manage stress and emotions, communicate effectively, and implement strategies to help maintain and direct attention. Some examples of this are Behavioural Parent Training, which teaches parents of children with ADHD how to support their children, Cognitive Behavioural Therapy (CBT) which aims to alter maladaptive thought patterns, and Mindfulness training, which can help in the self-regulation of attention (Modest-Lowe et al., 2015).

Link to Learning

Regular exercise can increase the effectiveness of ADHD drugs, possibly by boosting activity in the prefrontal cortex (Choi et al., 2015). Exercise also improves symptoms of depression and anxiety, especially in combination with psychotherapy, and may also be effective in preventing future depressive symptoms (Hu et al. 2020; Martinsen, 2008). Read this article about exercise intervention for ADHD from the Children and Adults with Attention deficit/hyperactivity disorder (CHADD) organization, to learn more.

The Autism Spectrum

Min is sitting in class. The fluorescent lights buzz and flicker like strobe lights across their vision. It becomes harder to understand the professor’s words in the cloud of static, and they begin to panic. They need to go somewhere darker and quieter, but lectures aren’t recorded, and they have trouble interacting with strangers so they don’t know anyone to get notes from. They want to rock in their seat so they can calm down and self-regulate, but they’ve been told it’s disruptive. As Min leaves after class, someone speaks to them, but they’re so overwhelmed that they can’t understand, and it feels like there’s something stopping the words in their brain from getting to their mouth. They put a practiced ‘friendly’ expression on their face, hoping it was appropriate for the social context. They get home just in time to start crying and rocking in the privacy of their room. They can’t think or stop, and they’re exhausted after. As the term goes on it gets harder to be in class and by the end, Min struggles to speak and leave the house. They have to ask for extensions on their final projects.

Symptoms and Traits

The term ‘autism’ describes a range of neurotypes that share underlying patterns of activity and connectivity. For this reason, it’s referred to as autism spectrum disorder (ASD), acknowledging that autistic people can present in a variety of ways with many different needs. Some autistic people refer to themselves as having ‘low-support needs’, meaning the impairment they experience requires relatively less support. Others refer to themselves as having ‘high support needs’, meaning that they need relatively more support to go about daily life. Min’s experience represents someone with lower support needs. Autistic people in these groups have the same kinds of traits, many of which can be categorized as differences in social communication and interaction with neurotypical people, or as restricted, repetitive behaviours. These two categories of traits come from the DSM-5, which is currently used in the diagnosis of ASD.

Social Communication and Interaction

There are 3 types of symptoms that may indicate differences in social communication and interaction (APA, 2013):

  1. Differences in or absence of social and emotional back and forth, like turn taking in conversation or sharing interests and emotions
  2. Differences in or absence of nonverbal communication behaviours such as eye contact, facial expression, gesture, and other body language
  3. Difficulty understanding and performing according to neurotypical social expectations, and difficulty or a lack of interest in developing and maintaining relationships

Because of differences in social behaviour and processing, many autistic people have trouble identifying lies and non-literal language (Williams et al., 2018, Pexman et al., 2010), and benefit from direct communication about social expectations. Autistic non-verbal communication can manifest in different ways; some autistic people have trouble making contact, possibly because the subcortical areas that respond to eye contact are more active in autistic brains, in particular, the amygdala (Hadjikhani, 2017). However, other autistic people have a tendency to stare. Some in the autistic community argue that these traits should be seen as a difference rather than an impairment, as they do not experience the same mismatch in social skills when interacting with other autistic people (Crompton et al., 2020; Davis & Crompton, 2021).

Restrictive and Repetitive Patterns of Behaviour

There are four types of symptoms that may indicate restrictive and repetitive patterns of behaviour (APA, 2013):

  1. Repetitive movements, speech or use of objects
  2. Preference for sameness and anxiety in response to changes or unexpected events
  3. Extremely focused or intense interests, including strong attachments to objects, preoccupation with specific subjects or activities
  4. Hyperreactivity, an increased response to certain sensory stimuli, and/or hyporeactivity, a decreased reactivity to certain sensory stimuli

Because they process sensory stimuli differently, some sensations can be more painful or more pleasurable than they would be for neurotypical people. This can lead to an insistence on sameness, as a way to avoid stimuli that is overwhelming and difficult to deal with (MacLennan, 2020). When sensory differences make sensations more pleasurable, autistic people may be motivated to engage with them repeatedly both because they are enjoyable, and to reduce anxiety. Often, these kinds of repetitive behaviours are called ‘stims’’ by autistic people, though non-autistic people also stim sometimes (e.g., tapping your foot or twirling your hair). Another common pattern of repeated behaviour for autistic people is the development of intense, long-lasting interests in particular subjects, often called special interests (Grove et al., 2018). Like people with ADHD, autistic people may be prone to hyperfocus, especially when engaging with a special interest.

Common Traits and Experiences

Shutdowns and Meltdowns

Shutdowns and meltdowns are a well-known but under-researched experience for many autistic people. Meltdowns are an externalization or release of stress that overwhelms an autistic person’s coping mechanisms, often preceded by sensory overload (Phung et al., 2021, Schaber, 2014). Externalization may involve screaming, stomping, sometimes self-injurious stimming and other similar behaviours that allow the autistic person to reduce internal tension.

Shutdowns are the internalized version of meltdowns, also occurring when the individual can’t deal with stress and sensory overload. Rather than releasing tension externally, the individual shuts down or dissociates to reduce their exposure to the sensory environment. Adults with autism report that this involves decreased sensation- for example, they may experience physical numbness and narrowing of vision. An autistic person experiencing shutdown may be unresponsive and exhausted (Phung et al., 2021, Schaber, 2014).

During meltdowns and shutdowns, autistic people report impaired cognitive and sensory processing, loss of communication skills, and less control over their body (Nason, 2019). Meltdowns and shutdowns are not intentional and generally can’t be stopped once they start. People experiencing meltdown should never be held down, as this practice has the potential to injure and in the worst cases can be fatal (Bartlett & Ellis, 2020, Vogel, 2014). Rather, care must be taken to help them escape triggering environments and reduce the amount of stimulation and stress they’re experiencing so they can recover (Myles & Southwick, 1999).

Dig Deeper

Autistic Masking and Burnout

Masking involves suppressing autistic traits and using a learned set of rules or scripts to blend in with neurotypical people. Not all autistic people can mask, and while masking may help some overcome certain social barriers, it’s described as tiring and anxiety provoking (Hull et al., 2017), and is associated with autistic burnout. Autistic burnout involves long-term exhaustion, reduced cognitive function, loss of previously mastered skills, social withdrawal and an increase in autistic traits (Higgins et al., 2021, Raymaker et al., 2020). One might lose the ability to perform facial expressions or use verbal language, sensory processing issues intensify, and the individual may need to spend less time socializing, speaking, and masking (Phung et al, 2021). While unmasking may be beneficial for long term health, it may also put autistic people at increased risk of violence. Data from police reports indicates that 42% of people killed by police in Canada were in mental distress, and data from the US indicates that 33-50% of people killed by police were disabled (Nicholson & Marcoux, 2018; Perry & Carter-Long, 2016). In many of these cases, disabled people displaying non-violent distress or behaviour associated with their disability or neurotype were reported as acting suspicious and were unable to respond to law enforcement as expected, at which point, police proceeded to use violent force. This was the case for Elijah Mccain, who was reported because he ‘looked sketchy’. In fact, Elijah was harmlessly stimming by waving his arms, and was wearing an open-faced ski mask to combat cold as a result of his chronic anemia. He had not committed any crime, but he was killed during the encounter because he was visibly distressed, and ‘tensed up’ when restrained (Thompkin, 2020). As in Elijah’s case, this risk is increased for those particularly affected by anti-Black or Indigenous racism, who are already more likely to be victims of police violence (Lett et al., 2020; Diamond & Hogue, 2021). In order to make it safe for all autistic people to take care of themselves and unmask, systemic forms of oppression must also be addressed.

A series of cartoon-like images with corresponding text. Included in the image are a picture of a glass half full with the word 'drink' below, a green apple with the word 'apple' below, a ball cap with the word 'hat' below, etc.
Figure PY.13 An example of a picture exchange communication system. Many AAC devices and apps combine image-based communication with text-to-speech so that users can communicate out loud. (Authors: Shashidhar Chandrashekhar and Jyothi S. Bommangoudar, licensed under CC BY-SA 3.0)

Non-Verbal Autism

Approximately 25-30% of autistic children don’t develop verbal language. Some may develop verbal language skills as they age, while others won’t. For years it was assumed that non-verbal autistic people couldn’t communicate or advocate for themselves, and while some do have trouble understanding language, others have good comprehension even if they can’t speak themselves (Rapin et al., 2009). In these cases, they may need access to alternate forms of communication like picture cards or text-to-speech apps (Figure PY.13). Autistic people given Augmentative and Alternative Communication (AAC) methods or technologies communicate significantly more and have better communication skills (Ganz et al., 2012). Forms of sign language are effective for many people on the spectrum and are helpful in improving outcomes autistic children (Goldstein, 2002), and autistic people with intellectual disabilities. Because verbal language is commonly lost during burnouts and meltdowns, AAC can also be helpful for those who are able to speak most of the time.

Link to Learning

Watch these videos on Augmentative and Alternative Communication (AAC), to learn more. This video from Fairfax County Schools, outlines Augmentative and Alternative Communication (AAC) devices and how they help give students a voice in their learning, and this video from Louisiana AEM showing how to create your own AAC board at home.

Autistic Strengths

Autistic people demonstrate several perceptual advantages, including above average pitch perception, spatial reasoning and recognition of visual patterns (Soulières et al., 2011, Stevenson & Gernsbacher, 2013). For example, some autistic people are hyperlexic, meaning that they can read at a higher level than expected for their age, possibly because they have an enhanced ability to recognize the visual characteristics of words (Mottron, 2006).  This superior processing for lower-level sensory information also results in superior memory abilities for some autistic people like Stephen Wiltshire, whose exceptional visual memory allows him to accurately illustrate entire cityscapes after a single flight across the skyline. Many autistic people also demonstrate subtle differences in empathic processes and moral reasoning. For example, one study found that they were less likely than neurotypical people to compromise their moral beliefs for personal gain, even when they were unobserved (Hu et al., 2020), and another found that they were less likely than neurotypical people to show bias towards members of their own group (Uono et al., 2021). Other autistic icons include animal behaviour consultant Temple Grandin, climate activist Greta Thunberg, artist Stephen Wiltshire, and multidisciplinary filmmaker Jorge R. Gutiérrez, who co-wrote and directed The Book of Life (Figure PY.14).

Series of photographs as described in figure caption
Figure PY.14 (a) Stephen Wiltshire, working on cityscape drawing from memory (Adapted from work by Gobierno CDMX, licensed under CC0 1.0). (b) Greta Thunberg, speaking at a climate strike in front of the Reichstag, Berlin (adapted from work by Stefan Müller, licensed under CC BY 2.0 ). (c) Temple Grandin delivering a TED talk in 2010 (adapted from work by Red Maxwell, licensed under CC BY 2.0 ). (d) Jorge R. Gutiérrez speaking at a panel on The Book of Life at San Diego comic con in 2014 (adapted from work by Gage Skidmore, licensed under CC BY-SA 2.0).

Causes of Autism

The strongest evidence suggests that autism is mostly heritable. One study involving 2 million children across multiple countries found that genetics accounted for almost 80% of one’s likelihood of being diagnosed with autism (Bai et al., 2019). Relatives of people with autism also have higher rates of related genetic syndromes and autistic-like traits (Chaste & Leboyer, 2022). Hundreds of genes have been identified as having some contribution, and many are involved in neural development, neurotransmitter function, synapse function (Hodges et al., 2020). One of these genes is SHANK3, which codes for synapses that use glutamate. Many autistic people have higher levels of glutamate in the primary motor and somatosensory cortices, and this difference is associated with atypical sensory processing.

Evidence also suggests that some of these genes affect the balance of certain neurotransmitters. For example, some autistic people have higher levels of excitatory neurotransmitters and lower levels of inhibitory neurotransmitters than neurotypical people, and this difference is associated with autistic social cognition and sensory processing (Al-Otaish et al., 2018; Cochran, 2015; He et al., 2021). Differences have also been found in the growth patterns of grey and white matter in certain areas of the cerebellum that are connected to the frontal and parietal lobes, and these differences are associated with autistic social traits and repetitive behaviour (D’Mello et al., 2015). As you might expect, people with autism also have more activity in primary sensory areas, which are associated with differences in sensory processing (Samson, 2011).

There is no support for the theory that vaccines or mercury contribute to the development of autism (DeStefano, 2007), and the paper that suggested this connection was found to have fabricated evidence (Godlee et al., 2011). Overall, evidence for environmental factors is weak and inconsistent.

Support for Autistic People and Caregivers

Historically, many techniques have aimed to suppress autistic traits, rather than helping autistic people to overcome disadvantages and meet their specific needs. For example, applied behavioural analysis (ABA) focuses on punishing autistic behaviours and coping mechanisms like stimming. ABA has been identified as an abusive therapy by the Autistic community (ASAN, 2021; Sandoval-Norton & Shkedy, 2019). Many adult autistics report that punishment for stimming negatively affects their self-confidence and sense of control over their bodies (Kapp et al., 2019, Gardiner, 2017). Stimming indicates that an autistic person may be coping with something overwhelming, so it’s better to help them address that if they need assistance. This is especially important for autistic children and non-verbal people with autism, who experience barriers in communicating their needs (Sandoval-Norton & Shkedy, 2019). If someone stims when they are in rooms with yellow light, the light may be overwhelming and could be changed to make them more comfortable. Alternatively, if they can tolerate wearing glasses, coloured lenses might help. If you don’t have these kinds of sensitivities, consider how it feels to try and walk with a rock in your shoe. If you can’t take the rock out, it might become the only thing you can think about, making it increasingly difficult to engage with your environment. However, if you take the rock out, you can recover and re-engage. These simple strategies can greatly impact an autistic person’s comfort and functioning.

Some autistic people find Social Skills Training (SST) helpful. Others argue that SST teaches neurodivergent people to mask and treat social interaction like math problems rather than engaging authentically and learning to identify and communicate their feelings (Roberts, 2022). It is argued that SST devalues neurodivergent social skills, and as we learned earlier autistic people don’t experience the same social issues when interacting with each other (Roberts, 2021; Davis & Crompton, 2021). SST may enhance an autistic person’s ability to mask and succeed in some domains, but this may also come at a cost to their own wellbeing, and it is possible that it wouldn’t be necessary if society were more socially accessible to them.

Given the diversity of people on the spectrum, appropriate supports and accommodations vary widely. Some have already been discussed. For example, AAC can be helpful for those struggling with verbal communication, and alterations to the environment can help with sensory issues. Autistic people may also benefit from occupational therapy to learn skills that can help them live more independently and meet their goals. For example, many autistic people have issues with coordination, and benefit from physical training to develop fine motor skills. Occupational therapists can also help identify autistic strengths and recommend modifications to activities and environments that allow autistic people to perform at their full capacity.

Autistic people and caregivers also experience higher rates of anxiety and depression than neurotypical people, in part because of social stigma and a lack of accessibility. There is evidence that CBT and mindfulness training are effective for treating anxiety and depression in autistic people and caregivers (Ridderinkhof et al., 2017), and that mindfulness training may also have a positive impact on emotional and sensory regulation (White et al., 2018).

Similarities and Differences: Diagnostic Bias

Classically, ADHD and autism are considered conditions that affect White, cisgender AMAB children (assigned male at birth). Some estimates suggest that there are four times as many AMAB children as AFAB (assigned female at birth) children diagnosed with these conditions (Ramtekkar, 2010). Recently however, adult diagnosis has become more common, and new data indicates that this gender difference shrinks with age ( Rutherford et al., 2016). On average, AFAB people are more likely to be misdiagnosed or diagnosed later in life (Adamis, 2022; Dworzynski et al., 2012). This may result from lack of awareness about different presentations of autism and ADHD. For example, AFAB people with ADHD are more likely to have ADHD-PI symptoms, and AFAB autistic people have fewer social traits and more sensory traits (Lai et al., 2011; Adamis, 2022) than AMAB children. There is likely also a gender bias, as AMAB children are more likely to be referred for diagnosis than AFAB children with equivalent traits (Scuitto et al., 2004). On average AFAB autistic children with official diagnosis also have higher levels of autistic traits than AMAB children, suggesting that AFAB children need to experience more impairment to be diagnosed (Rutherford et al., 2016). Interestingly some data indicates that there are higher than average rates of transgender or gender-diverse identity in neurodiverse populations. For example, Warrier et al. (2020) found that 24% of gender-diverse people in their sample had autism, as compared to only 5% of cisgender people.

Evidence suggests there is also a diagnostic bias against people of color, particularly Black people, as Black autistic children are 2 more likely to be misdiagnosed with conduct disorder than White autistic children with the same traits (Mandell et al., 2006; Fombonne & Zuckerman, 2022). Similarly, Black children are 5.1 times more likely to be diagnosed with adjustment disorder and 2.4 times more likely to be diagnosed with conduct disorder, while White children with the same traits are more likely to be diagnosed with ADHD (Ballentine, 2019). No difference has been found in levels of ADHD or autism-related traits between these groups. If children of color and non-Hispanic White children display the same rates of ADHD and autism-like behaviours but are diagnosed differently, then it’s likely that race-based bias is affecting the way they are being perceived by diagnosticians (Fadus et al., 2019).

Similarities and Differences: Sensory Processing

People with ADHD and/or autism have differences in sensory processing that affect the way they react to stimuli. For example, some are hypo-reactive to interoceptive stimuli, which are sensations that come from inside the body, like hunger pains or the feeling of a full bladder. If you have trouble with interoception, you may struggle to identify sensations like pain or hunger, which can cause distress as you may not know how to address unpleasant sensory experiences. Many autistic people also have alexithymia, meaning that they have trouble sensing and identifying their own emotions and the emotions of others. Others are hyper-reactive to certain stimuli, like sound, light, and physical sensation. These people may need to wear tinted lenses or ear plugs and may avoid certain kinds of material for clothing in order to avoid becoming overstimulated. It is also possible to be both under and over responsive to a kind of stimuli, and to switch between the two (Wigham, 2014), and some sensory differences can also result in positive experiences. For example, a heightened response to sound can enhance enjoyment of music, while differences in somatosensory processing might make it feel really good or soothing to rock back and forth. Everyone engages in this kind of sensory seeking behaviour sometimes, but autistic people may be motivated to do this more often, both for enjoyment and for self-care.

Sensory differences influence cognitive and behavioural differences as well. For example, someone with ADHD may have trouble maintaining attention because they are hyper-reactive to sound and are distracted by noises in the environment. This hyper-reactivity could result from a reduced ability to filter stimuli as evidenced by neuroimaging studies, which have found higher activity in lower-level sensory areas like the superior and inferior colliculi, which help the body direct itself toward visual and auditory stimuli (Panagiotidi et al., 2020). Alternatively, people with ADHD may appear inattentive because they have low sensitivity to sound and attempts to get their attention haven’t registered (Shimizu et al., 2014). One theory suggests that some people with ADHD are under stimulated at baseline, resulting in hyper-activity and sensation-seeking behaviours to self-generate stimulation. There is evidence that increased environmental simulation can enhance performance for some people with ADHD. For example, Söderlund et al. (2007) found that subjects with ADHD did better on cognitive tasks with white noise in the background. Remember also that stimulant medications prescribed to people with ADHD act by increasing neural stimulation in areas that are under-active (Ogrim et al., 2013).

In people with autism, sensory reactivity can predict stimming, insistence on sameness, and special interests (Kapp et al., 2019). Like people with ADHD, people with autism have trouble ignoring certain stimuli. This might be because Autistic people take longer to habituate, meaning that their nervous systems keep reacting to unchanging stimuli longer than neurotypical people’s systems do. Autistic people also seem to filter and group stimuli less than neurotypical people, possibly resulting from differences in association areas, which combine information from different senses. Some evidence suggests that in autistic people, these differences result in better processing for individual stimuli than for groups (Proff et al., 2022; Quintin, 2019). This is a tendency toward local processing, like people with ADHD. For those with ADHD however, this might result from difficulty shifting attention from one detail to another (Gargaro et al., 2015; Cardillo et al., 2020).


Icon for the Creative Commons Attribution 4.0 International License

Introduction to Psychology & Neuroscience (2nd Edition) Copyright © 2020 by Edited by Leanne Stevens & Jennifer Stamp is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

Share This Book