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Special Reports Curated collections of articles on special topics in autism.
Illustration of a row of transparent heads in profile--we can see different colors in the brain areas.
ILLUSTRATION BY
LAURÈNE BOGLIO

How is autism diagnosed? What explains the rise in autism’s prevalence? How much do genes contribute to the condition? What about the environment?

In this section of Spectrum, dubbed Autism 101, we answer these and other questions about autism. Each article pulls together the latest science to reflect what we know.

Autism 101 is designed to both provide information and highlight knowledge gaps, indicating where data on a subject are absent or contradictory. Like our understanding of autism, this section is evolving, so please check back often.


Most read articles

two layers of hands in motion overlap in red and blue

Repetitive behaviors and ‘stimming’ in autism, explained

by  /  31 January 2020

Restricted interests and repetitive behaviors constitute one of two criteria that define autism in the diagnostic manual for psychiatry.

Autism prevalence in the United States explained

by  /  3 September 2020

The bulk of the increase in autism prevalence stems from a growing awareness of the condition and changes to the diagnostic criteria.

child with someone sleeping in cloud-like brain

Sleep problems in autism, explained

by  /  6 February 2020

Many people with autism have difficulty falling and staying asleep, but there may be ways to help them.

stork flying with an alarm clock, dice and a crescent moon

The link between parental age and autism, explained

by  /  28 January 2020

Older men and women are more likely than young ones to have a child with autism, but this connection is not straightforward.

Autism theories and research

Illustration of a strong man holding up a oversized brain

The extreme male brain, explained

by  /  1 May 2019

The ‘extreme male brain’ theory suggests that autism is an exaggeration of systematic sex differences in ways of thinking.

The female protective effect, explained

by  /  1 May 2019

One of the leading theories of autism posits that girls and women are biologically protected from the condition.

The signaling imbalance theory of autism, explained

by  /  1 May 2019

The signaling imbalance theory holds that the brains of autistic people are hyper-excitable because of either excess neuronal activity or weak brakes on that activity.

Illustration shows the world is distorted through a point of view pair of glasses

The predictive coding theory of autism, explained

by  /  1 May 2019

In autism, a person’s brain may not form accurate predictions of imminent experiences, or even if it does, sensory input may override those predictions.

overlapping network of connections in the brain

The connectivity theory of autism, explained

by  /  1 May 2019

A growing body of evidence suggests that autism involves atypical communication between brain regions, but how and where in the brain this plays out is unclear.

Illustration of red figures on a big blue brain are serotonin signaling

Serotonin’s link to autism, explained

by  /  1 May 2019

Serotonin, the brain chemical best known for its link to depression, may also be involved in autism.

many hands reaching for and sharing papers

Preprints of autism research, explained

by  /  11 March 2020

Over the past decade, biologists have increasingly been posting their research results on preprint servers, ahead of the results’ publication in traditional scientific journals.

A DNA helix showing common and rare variants

The multiple hits theory of autism, explained

by  /  1 May 2019

Researchers are studying how a combination of genetic ‘hits’ may contribute to autism’s diversity.

Biological factors

Illustration shows a maze of elements: human brain, medicine, chromosome, factory, clouds and lightning bolts

Environmental risk for autism, explained

by  /  5 November 2018

Autism results from an interplay between genetics and the environment, but it has been tough to nail down the environmental factors involved.

Hands on background of microarray and other genetic information

Genetic testing for autism, explained

by  /  10 April 2019

No genetic test can say whether a person has autism, but it may point to a cause for the condition or for any related complications.

stork flying with an alarm clock, dice and a crescent moon

The link between parental age and autism, explained

by  /  28 January 2020

Older men and women are more likely than young ones to have a child with autism, but this connection is not straightforward.

Illustration of research mice forming the letter 'X'.

Fragile X syndrome’s link to autism, explained

by  /  10 October 2018

Fragile X syndrome is a leading genetic cause of autism. People who have either condition often share certain traits, such as difficulties in social situations.

linked hands in a pattern intertwined with DNA showing some broken parts, symbolizing mutations

Rett syndrome’s link to autism, explained

by  /  21 October 2019

Studies of Rett syndrome hint at genes, cells and brain circuits that may be involved in autism — and may pave the way to treatments for both conditions.

The link between antidepressants and autism, explained

by  /  6 September 2018

Taking antidepressants during pregnancy is unlikely to raise the risk of having a child with autism.

Illustration shows heads and brains inside at various sizes.

Autism’s relationship to head size, explained

by  /  9 April 2020

Some people with autism have an unusually large head. What causes the enlargement? And does it have any bearing on outcome?

DNA inside of human form

Autism genetics, explained

by  /  3 September 2020

The more scientists dig into DNA, the more intricate its contribution to autism seems to be. Here, we unravel the complex genetics of autism.

four brain areas marked with flags: Cortex, amygdala, hippocampus, cerebellum

Brain structure changes in autism, explained

by  /  15 October 2020

Autistic people have distinct patterns of brain development, which sometimes result in differences in brain structure. Here’s what we know about those differences.

Diagnosis and Interventions

Autism prevalence in the United States explained

by  /  3 September 2020

The bulk of the increase in autism prevalence stems from a growing awareness of the condition and changes to the diagnostic criteria.

People standing with shapes around them

The evolution of ‘autism’ as a diagnosis, explained

by  /  9 May 2018

From a form of childhood schizophrenia to a spectrum of conditions, the characterization of autism in diagnostic manuals has a complicated history.

An illustration shows colored blocks with a child's hand and an adult's hand moving them.

Early interventions, explained

by  /  4 October 2018

The accepted wisdom in autism research holds that early intervention offers the best promise for an autistic child’s well-being. But how effective are these therapies?

A drawing shows the word 'autism' formed of loose letters under a magnifying glass.

Autism diagnosis, explained

by  /  5 November 2018

New and improved autism screens and diagnostic tools promise to streamline the long path to an autism diagnosis.

Illustration of a neuron on top of a marijuana leaf surrounded by psychadelic colors.

Cannabis and autism, explained

by  /  7 September 2020

Autistic people and their families are increasingly experimenting with marijuana to try to ease problems such as insomnia, epilepsy and chronic pain — and traits of autism. But there is little evidence for its safety or effectiveness.

Living with autism

a green head has a 'top' that is red--and a hand is lifting the top to let steam out.

Autistic burnout, explained

by  /  30 March 2020

‘Autistic burnout’ is the intense physical, mental or emotional exhaustion, often accompanied by a loss of skills, that some adults with autism experience.

two layers of hands in motion overlap in red and blue

Repetitive behaviors and ‘stimming’ in autism, explained

by  /  31 January 2020

Restricted interests and repetitive behaviors constitute one of two criteria that define autism in the diagnostic manual for psychiatry.

child with someone sleeping in cloud-like brain

Sleep problems in autism, explained

by  /  6 February 2020

Many people with autism have difficulty falling and staying asleep, but there may be ways to help them.

silhouette of head with illustrated text

Social communication in autism, explained

by  /  19 April 2018

Communication problems have always been considered a core feature of autism. Yet there are substantial and wide-ranging differences in how people with autism communicate.

a human brain model made of springs is shaking on its spring base

The link between epilepsy and autism, explained

by  /  21 October 2019

Autism and epileptic seizures often go hand in hand. What explains the overlap, and what does it reveal about autism’s origins?

Conditions that accompany autism, explained

by  /  25 July 2018

More than half of people on the spectrum have four to five other conditions. Which conditions, and how and when they appear, varies from one autistic person to the next.

Female head shape cut out of pink paper, under magnifying glass. Male head is in blue, opposite the female.

Autism’s sex ratio, explained

by  /  13 June 2018

More boys than girls have autism; diagnostic biases and genetic factors may explain the skewed sex ratio.

Illustration showing two hands plugging cables into different areas of the brain, eg. prefrontal cortex, motor cortex, etc.

Motor difficulties in autism, explained

by  /  13 August 2020

Most people with autism have motor difficulties, ranging from an atypical gait to problems with handwriting, but researchers still have much to learn about their causes and consequences.

Illustration of hand pressing one orange button on a keyboard with keys of various colors.

Gender and sexuality in autism, explained

by  /  18 September 2020

Gender and sexuality appear to be more varied among autistic people than among neurotypical people. What do scientists know about the connection?