People with autism spectrum disorder were traditionally viewed as having low intelligence based on their verbal communication skills.
However, autism is today considered to be a condition separate from intellectual disability. We know that autistic people can have a wide range of learning and thinking skills that can make them both severely challenged and gifted.
In this article, we help you better understand the difference between high and low functioning autism as well as the complex link between autism and intelligence.
In What Areas Can Autism Affect a Person’s Day to Day Life?
For people with autism spectrum disorder and their families, day to day life is filled with numerous challenges. The condition is characterized by various degrees of learning difficulties. Although many people may be able to live independently, others need lifelong support and care.
Some of the most common areas in which autism affects day-to-day life are communication, social interactions, and living skills.
Depending on where on the spectrum they fall, people with autism have various levels of communication abilities. Some have very limited speaking capacities or are not able to use language at all. They may have significant difficulties understanding what other people are saying. Non-verbal communication including hand gestures, eye contact, and facial expressions may also be challenging for individuals with autism who are unable to fully grasp body language.
Typical patterns of language use and behaviors in children and adults with autism include:
- Repetitive or rigid language, like saying things that have no meaning or repeating the same words, a condition known as echolalia
- Machine-like and monotonic speech
- Speaking in a high-pitched or “sing-song” voice
- Uneven language development, for instance, having an extensive vocabulary only within a specific area of interest
- Limited nonverbal conversation skills, such as the inability to use gestures and facial expressions.
However, many high functioning autistic people have a rich vocabulary and can talk about specific subjects in great detail, even though they may still experience problems with verbal intonation and the rhythm of words and sentences. Regardless of their level of functioning, these difficulties may significantly affect their ability to interact with others.
One of the main defining characteristics of autism spectrum disorder is social dysfunction. People with autism often show little interest in the world around them and have a limited understanding of other people’s feelings and ideas.
Autistic individuals frequently experience social interactions as unpredictable and frightening. For example, they may not understand the purpose of saying hello and goodbye, showing facial expressions, waiting for their turn to speak, or maintaining eye contact during conversation. As a consequence, they may find it difficult to maintain friendships, which can lead to further social isolation.
High functioning autistic individuals are able to adopt coping methods and acquire social skills that will help them fit in. Their issues with social interactions are rarely noticeable in casual conversations. Nevertheless, even high functioning autistic individuals almost always struggle with some level of discomfort in social interactions.
Everyday tasks such as self-care, home organization, cleaning, cooking, shopping, and transportation can be a challenge for autistic people. At the same time, daily living skills are indispensable for being able to live independently, rely less on others, as well as for improving self-esteem and quality of life in general. Research suggests that impairments in daily living skills in individuals with autism are directly related to their cognitive abilities and can often improve throughout childhood and adolescence.
Several other issues can make the normal day-to-day functioning of autistic individuals difficult:
Most people with autism spectrum disorder, including those with high-functioning autism, are affected by sensory overload. Crowds, excessive noise, bright lights, and strong tastes and smells may feel overwhelming and disruptive because they provide more sensory input than the autistic brain can process.
Autistic people frequently struggle to control their emotions in new and unpredictable situations and transition to another activity or setting. These stressful situations may trigger unusually intense emotional reactions compared to their neurotypical peers.
Resistance to change
Individuals with autism are generally resistant to change and prefer familiar situations and activities. Any disruption in their routines could cause frustration and anger.
Autism is a neurodevelopmental disorder and the issues mentioned above are consequences of the way different parts of the brain form and connect to one another.
What Parts of the Brain are Affected by Autism?
Research shows that some parts of the brain are structurally different in autistic than non-autistic people. For example, children and adolescents with autism have an enlarged hippocampus, the area of the brain responsible for learning and memory. Furthermore, the size of the amygdala—the region of the brain that deals with emotions—also differs in people with autism and neurotypical individuals. The cortex, the brain’s outer layer, seems to have a different pattern of thickness in people with and without autism.
One of the key brain regions affected by autism is the cerebellum, the brain structure that plays a crucial role in cognition and social interactions. Autistic individuals are known to have decreased amounts of gray matter in parts of the cerebellum. This region of the brain is also indispensable for movement and learning motor skills, which may explain challenges with coordination and fine and gross motor skills typical for autism spectrum disorder.
However, the way that these differences in brain structure affect autism and yield autistic savants or people with below-average intelligence is still not fully understood.
Does family background contribute towards autism?
Studies show that children in families with a history of brain conditions are at increased risk of autism. The more closely related the family members with these conditions, the greater the chances of having autism. Moreover, the odds increase if there are other children with autism, attention deficit hyperactivity disorder (ADHD), or intellectual disability in the family, or if a parent has schizophrenia, bipolar disorder, anxiety, or depression.
Nevertheless, it is only possible to identify a specific genetic cause of autism in around 15% of cases. Brain development is influenced by a complex combination of genetic and environmental factors. In other words, if a person is genetically predisposed to autism, environmental elements will increase their risk of having the condition.
Autism prevalence in the United States
An estimated 222 per 10,000 children in the United States were diagnosed with autism spectrum disorder in 2020. This is one of the highest autism prevalence rates in the world, after Hong Kong and South Korea.
An earlier study suggested that some ethnic groups seemed to be more predisposed to autism than others. The study found an increased risk of being diagnosed with autism in children of American-born Hispanic and African American mothers as well as African American, Central or South American, Filipino, and Vietnamese foreign-born mothers.
However, newer research has demonstrated that the prevalence of autism is in fact very similar among racial groups. The earlier disparity might have been due to the fact that diagnostic practices and services are not equally available to different ethnic groups, in addition to certain environmental factors.
Continue reading to learn more about the difference between high and low functioning autism.
High Functioning Autism vs Low Functioning Autism
People with autism are often described as being either high or low-functioning, even though these are not official diagnoses within autism spectrum disorder. Differences between the two levels of autism can be extreme, but most individuals fall somewhere in between—they are low functioning in some areas and high functioning in others.
High functioning autism
High functioning autism is a term used to describe individuals with autism spectrum disorder who don’t have any intellectual disabilities. They are able to learn how to overcome or control their symptoms and lead independent lives.
Although high functioning autism is typically associated with better functional skills and positive long-term outcomes, in reality, this is not always the case. People with high functioning autism may have advanced language and cognitive skills and still experience significant challenges when it comes to communication, emotions, and social interaction. What’s more, being aware of the differences between themselves and their neurotypical peers can increase anxiety and depression.
Low functioning autism
Low functioning autism, on the other hand, is a term used to describe children and adults with the most severe symptoms of autism. These individuals are diagnosed with level 3 of autism spectrum disorder.
According to the Center for Autism Research, the rate of autistic patients with intellectual disability—an IQ score below 70—is around 40%. At the same time, the intellectual disability rate within the general population is about 1%. People with low functioning autism generally suffer from one or more forms of intellectual disability such as Rett syndrome, Down syndrome, and Angelman syndrome, for example.
Individuals with low functioning autism experience some or all of the most common symptoms of autism, like repetitive behaviors, limited social abilities, and impaired communication skills. These symptoms are also more pronounced and severe than in high functioning autism. In addition, people with low functioning have difficulties learning how to cope and control their symptoms. They are not able to live independently and require extensive supervision and support.
Intelligence tests are a fundamental component of diagnosing children and adolescents with autism spectrum disorder. Let’s take a closer look.
Types of IQ
The intelligence quotient (IQ) is a measure of human intelligence, which is commonly evaluated with the help of Wechsler scales in studies on autism. Wechsler Adult Intelligence Scale (WAIS) and Wechsler Intelligence Scales for Children (WISC) are used to measure a combination of performance and verbal intelligence in autistic children and adults. The results can help determine the areas in which individual support plans and treatment programs should be developed for these individuals.
Performance IQ (PIQ)
Nonverbal intelligence is the ability to analyze information and solve problems using visual, practical reasoning. The performance or nonverbal IQ is a measure of intelligence that doesn’t require the use of words or language. It measures a person’s nonverbal reasoning, spatial processing skills, attention to detail, and hand-eye coordination skills.
Verbal IQ (VIQ)
Verbal IQ is the ability to analyze information and solve problems using language-based reasoning. This reasoning involves reading or listening to words, writing, and engaging in a conversation. Verbal intelligence measures verbal reasoning, comprehension of verbal information, and the ability to express knowledge through spoken language.
Intellectual disability measured by IQ scores may vary depending on the type of test used. Non-verbal children, for example, can obtain low scores on verbal IQ tests but may score at an age-appropriate level on tests of spatial intelligence. In general, autistic individuals perform better on performance IQ than verbal IQ tests, consistent with the cognitive and social deficits of autism.
Autistic individuals with high IQ typically underperform on cognitive tests compared to neurotypical adults or children in the same IQ range. At the same time, people with autism spectrum disorder who have low IQ perform similarly to their neurotypical counterparts. Research suggests that cognitive deficits in high-IQ autistic people may have underlying causes that are not rooted in the condition itself.
Is IQ related to the range of function of an autistic person?
The intelligence and range of function in individuals with autism are highly but not perfectly correlated. IQ scores generally relate to communication skills and adapting to daily life, however, they are not exact indicators of cognitive functioning and the ability of a person with autism to navigate the day to day life. Studies show that many people with autism have lower life skills than what would be expected given their cognitive abilities. For example, a person with a high IQ who is considered high functioning may be significantly impaired in daily activities.
This is why taking the intelligence quotient to categorize autistic individuals can be misleading. An individual’s level of functioning can be more impacted by underlying mental health issues, such as attention-deficit hyperactivity disorder (ADHD), substance abuse, gastrointestinal issues, obsessive compulsive disorder (OCD), depression, and anxiety, than by IQ.