Autism 101
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The link between maternal infection and autism, explained
Having an infection during pregnancy is tied to a small increase in the chances of having an autistic child, but the connection may not be causal.
![Illustration of a pregnant woman seated next to a large diagram of the brain featuring chromosomes, bacteria and other microbes.](https://www.thetransmitter.org/wp-content/uploads/2022/12/1200-maternal-inflamation-1024x683.webp)
The link between maternal infection and autism, explained
Having an infection during pregnancy is tied to a small increase in the chances of having an autistic child, but the connection may not be causal.
Autism prevalence in the United States, explained
The bulk of the increase in autism prevalence stems from a growing awareness of the condition and changes to the diagnostic criteria.
![Children scattered around a grid with a beam counting them](https://www.thetransmitter.org/wp-content/uploads/2020/09/Prevalence844.jpg)
Autism prevalence in the United States, explained
The bulk of the increase in autism prevalence stems from a growing awareness of the condition and changes to the diagnostic criteria.
Sleep problems in autism, explained
Many people with autism have difficulty falling and staying asleep, but there may be ways to help them.
![Illustration shows child's head, with an EEG background, and a sleeping figure floating in the clouds above his head.](https://www.thetransmitter.org/wp-content/uploads/2020/02/Sleep-844.jpg)
Sleep problems in autism, explained
Many people with autism have difficulty falling and staying asleep, but there may be ways to help them.
Double empathy, explained
The double empathy theory challenges the idea that social difficulties are specific to autism and suggests that problems arise from a mismatch in perspective between autistic and non-autistic people.
![Illustration shows a woman whose mouth is covered by a cloud and whos eyes are covered by a cloud.](https://www.thetransmitter.org/wp-content/uploads/2021/07/20210722-Empathy844.jpg)
Double empathy, explained
The double empathy theory challenges the idea that social difficulties are specific to autism and suggests that problems arise from a mismatch in perspective between autistic and non-autistic people.
Autism theories and research
The extreme male brain, explained
The ‘extreme male brain’ theory suggests that autism is an exaggeration of systematic sex differences in ways of thinking.
![Illustration of a strong man holding up a oversized brain](https://www.thetransmitter.org/wp-content/uploads/2019/05/20190501-ExtremeMale-844.jpg)
The extreme male brain, explained
The ‘extreme male brain’ theory suggests that autism is an exaggeration of systematic sex differences in ways of thinking.
The female protective effect, explained
One of the leading theories of autism posits that girls and women are biologically protected from the condition.
![](https://www.thetransmitter.org/wp-content/uploads/2019/04/20190424_Female-protective_1120.jpg)
The female protective effect, explained
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
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.
![](https://www.thetransmitter.org/wp-content/uploads/2019/05/20190501-E-I-imbalance844.jpg)
The signaling imbalance theory of autism, explained
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.
The predictive coding theory of autism, explained
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.
![Illustration shows the world is distorted through a point of view pair of glasses](https://www.thetransmitter.org/wp-content/uploads/2018/05/20190501-Predictive844.jpg)
The predictive coding theory of autism, explained
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.
The connectivity theory of autism, explained
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.
![overlapping network of connections in the brain](https://www.thetransmitter.org/wp-content/uploads/2019/05/20190501-ContradictoryConnect_844.jpg)
The connectivity theory of autism, explained
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.
Serotonin’s link to autism, explained
Serotonin, the brain chemical best known for its link to depression, may also be involved in autism.
![Illustration of red figures on a big blue brain are serotonin signaling](https://www.thetransmitter.org/wp-content/uploads/2019/05/20190501-Serotonin-844.jpg)
Serotonin’s link to autism, explained
Serotonin, the brain chemical best known for its link to depression, may also be involved in autism.
Preprints of autism research, explained
Over the past decade, biologists have increasingly been posting their research results on preprint servers, ahead of the results' publication in traditional scientific journals.
![many hands reaching for and sharing papers](https://www.thetransmitter.org/wp-content/uploads/1970/01/20200311-Preprint844.jpg)
Preprints of autism research, explained
Over the past decade, biologists have increasingly been posting their research results on preprint servers, ahead of the results' publication in traditional scientific journals.
Double empathy, explained
The double empathy theory challenges the idea that social difficulties are specific to autism and suggests that problems arise from a mismatch in perspective between autistic and non-autistic people.
![Illustration shows a woman whose mouth is covered by a cloud and whos eyes are covered by a cloud.](https://www.thetransmitter.org/wp-content/uploads/2021/07/20210722-Empathy844.jpg)
Double empathy, explained
The double empathy theory challenges the idea that social difficulties are specific to autism and suggests that problems arise from a mismatch in perspective between autistic and non-autistic people.
The multiple hits theory of autism, explained
Researchers are studying how a combination of genetic ‘hits’ may contribute to autism’s diversity.
![A DNA helix showing common and rare variants](https://www.thetransmitter.org/wp-content/uploads/2019/05/20190501-multiple-hits844.jpg)
The multiple hits theory of autism, explained
Researchers are studying how a combination of genetic ‘hits’ may contribute to autism’s diversity.
Pathological demand avoidance in autism, explained
Some clinicians say the term describes a subtype of autism, but others dispute its validity and say it is harmful to the autistic community.
![Child stands with back to group of large signs offering directions.](https://www.thetransmitter.org/wp-content/uploads/2022/08/1200-pathological-demand-avoidance-1024x683.webp)
Pathological demand avoidance in autism, explained
Some clinicians say the term describes a subtype of autism, but others dispute its validity and say it is harmful to the autistic community.
Funding for autism research, explained
Biomedical research costs money. And applying for research funding can be a long and complicated process.
![a microscope shines light on a stack of bills](https://www.thetransmitter.org/wp-content/uploads/2020/04/NIH-844.jpg)
Funding for autism research, explained
Biomedical research costs money. And applying for research funding can be a long and complicated process.
Biological factors
Autism’s link to chromatin remodeling, explained
Many of the genes strongly linked to autism are involved in the remodeling of chromatin, the complex of DNA and proteins that makes up chromosomes. Scientists are just beginning to understand why.
![Playful clay chromatin strand is not plugged in, there fore, not turned on](https://www.thetransmitter.org/wp-content/uploads/2021/07/Chromatin1000.jpg)
Autism’s link to chromatin remodeling, explained
Many of the genes strongly linked to autism are involved in the remodeling of chromatin, the complex of DNA and proteins that makes up chromosomes. Scientists are just beginning to understand why.
DNA methylation in autism, explained
How chemical tags called methyl groups position themselves on genetic sequences may hint at some of the causes of autism.
![Illustration of DNA helix highlighting the methylation process.](https://www.thetransmitter.org/wp-content/uploads/2021/12/1200-methylation-1024x683.webp)
DNA methylation in autism, explained
How chemical tags called methyl groups position themselves on genetic sequences may hint at some of the causes of autism.
Genetic testing for autism, explained
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.
![Hands on background of microarray and other genetic information](https://www.thetransmitter.org/wp-content/uploads/2019/04/20190410-ClinGenExplainer844.jpg)
Genetic testing for autism, explained
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.
The link between parental age and autism, explained
Older men and women are more likely than young ones to have a child with autism, but this connection is not straightforward.
![stork flying with an alarm clock, dice and a crescent moon](https://www.thetransmitter.org/wp-content/uploads/2017/11/parental-844.jpg)
The link between parental age and autism, explained
Older men and women are more likely than young ones to have a child with autism, but this connection is not straightforward.
Environmental risk for autism, explained
Autism results from an interplay between genetics and the environment, but it has been tough to nail down the environmental factors involved.
![Illustration shows a maze of elements: human brain, medicine, chromosome, factory, clouds and lightning bolts](https://www.thetransmitter.org/wp-content/uploads/2018/11/20181105-Environ844.jpg)
Environmental risk for autism, explained
Autism results from an interplay between genetics and the environment, but it has been tough to nail down the environmental factors involved.
Fragile X syndrome’s link to autism, explained
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.
![Illustration of research mice forming the letter 'X'.](https://www.thetransmitter.org/wp-content/uploads/2018/10/20181009-FragileX844.jpg)
Fragile X syndrome’s link to autism, explained
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.
Rett syndrome’s link to autism, explained
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.
![linked hands in a pattern intertwined with DNA showing some broken parts, symbolizing mutations](https://www.thetransmitter.org/wp-content/uploads/2019/10/20190921-Rett844.jpg)
Rett syndrome’s link to autism, explained
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
Taking antidepressants during pregnancy is unlikely to raise the risk of having a child with autism.
![](https://www.thetransmitter.org/wp-content/uploads/1970/01/20180905-AntiDepressantExplainer844jpg.jpg)
The link between antidepressants and autism, explained
Taking antidepressants during pregnancy is unlikely to raise the risk of having a child with autism.
Autism’s relationship to head size, explained
Some people with autism have an unusually large head. What causes the enlargement? And does it have any bearing on outcome?
![Illustration shows heads and brains inside at various sizes.](https://www.thetransmitter.org/wp-content/uploads/1970/01/20200409-HeadsizeExplainer844.jpg)
Autism’s relationship to head size, explained
Some people with autism have an unusually large head. What causes the enlargement? And does it have any bearing on outcome?
Autism genetics, explained
The more scientists dig into DNA, the more intricate its contribution to autism seems to be. Here, we unravel the complex genetics of autism.
![DNA helix inside the human body](https://www.thetransmitter.org/wp-content/uploads/2020/09/GeneticsExplain844.jpg)
Autism genetics, explained
The more scientists dig into DNA, the more intricate its contribution to autism seems to be. Here, we unravel the complex genetics of autism.
The link between vitamins, supplements and autism, explained
Too little — or too much — of certain substances during pregnancy may increase the odds of having a child with autism. Here we explain what scientists know about these associations.
![Baby in utero surrounded by pills, on bright blue background](https://www.thetransmitter.org/wp-content/uploads/2021/04/20100414-VitaminD844.jpg)
The link between vitamins, supplements and autism, explained
Too little — or too much — of certain substances during pregnancy may increase the odds of having a child with autism. Here we explain what scientists know about these associations.
Brain structure changes in autism, explained
Autistic people have distinct patterns of brain development, which sometimes result in differences in brain structure. Here's what we know about those differences.
![four brain areas marked with flags: Cortex, amygdala, hippocampus, cerebellum](https://www.thetransmitter.org/wp-content/uploads/2020/10/20201015-BrainStructure844.jpg)
Brain structure changes in autism, explained
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
Decisional capacity and informed consent, explained
To include more autistic people in research, here's what scientists need to know about informed consent procedures for study participants who have impaired decision-making capacity.
![Illustration of a form being signed.](https://www.thetransmitter.org/wp-content/uploads/2023/01/1200-decisional-capacity-1024x683.webp)
Decisional capacity and informed consent, explained
To include more autistic people in research, here's what scientists need to know about informed consent procedures for study participants who have impaired decision-making capacity.
Autism prevalence in the United States, explained
The bulk of the increase in autism prevalence stems from a growing awareness of the condition and changes to the diagnostic criteria.
![Children scattered around a grid with a beam counting them](https://www.thetransmitter.org/wp-content/uploads/2020/09/Prevalence844.jpg)
Autism prevalence in the United States, explained
The bulk of the increase in autism prevalence stems from a growing awareness of the condition and changes to the diagnostic criteria.
The evolution of ‘autism’ as a diagnosis, explained
From a form of childhood schizophrenia to a spectrum of conditions, the characterization of autism in diagnostic manuals has a complicated history.
![People standing with shapes around them](https://www.thetransmitter.org/wp-content/uploads/2018/05/DSM-5Explainer844.jpg)
The evolution of ‘autism’ as a diagnosis, explained
From a form of childhood schizophrenia to a spectrum of conditions, the characterization of autism in diagnostic manuals has a complicated history.
Early interventions, explained
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?
![An illustration shows colored blocks with a child's hand and an adult's hand moving them.](https://www.thetransmitter.org/wp-content/uploads/2018/10/2018101-ABA-844-V2.jpg)
Early interventions, explained
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?
Autism diagnosis, explained
New and improved autism screens and diagnostic tools promise to streamline the long path to an autism diagnosis.
![A drawing shows the word 'autism' formed of loose letters under a magnifying glass.](https://www.thetransmitter.org/wp-content/uploads/2018/11/DiagnosisExplainer844.jpg)
Autism diagnosis, explained
New and improved autism screens and diagnostic tools promise to streamline the long path to an autism diagnosis.
Cannabis and autism, explained
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.
![Illustration of a neuron on top of a marijuana leaf surrounded by psychadelic colors.](https://www.thetransmitter.org/wp-content/uploads/2020/09/20200907-Cannabis-844b.jpg)
Cannabis and autism, explained
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
Anorexia’s link to autism, explained
People with anorexia are more likely to be autistic than those without the eating disorder, but the interplay between the two conditions is complex.
![The illustration shows two plates of food, one full of a variety of foods, and another with a few foods arranged in a particular way.](https://www.thetransmitter.org/wp-content/uploads/2020/12/Anorexia_and_Autism_02_844.jpg)
Anorexia’s link to autism, explained
People with anorexia are more likely to be autistic than those without the eating disorder, but the interplay between the two conditions is complex.
Autistic burnout, explained
‘Autistic burnout’ is the intense physical, mental or emotional exhaustion, often accompanied by a loss of skills, that some adults with autism experience.
![a green head has a 'top' that is red--and a hand is lifting the top to let steam out.](https://www.thetransmitter.org/wp-content/uploads/1970/01/Burnout_Explainer844.jpg)
Autistic burnout, explained
‘Autistic burnout’ is the intense physical, mental or emotional exhaustion, often accompanied by a loss of skills, that some adults with autism experience.
Repetitive behaviors and ‘stimming’ in autism, explained
Restricted interests and repetitive behaviors constitute one of two criteria that define autism in the diagnostic manual for psychiatry.
![two layers of hands in motion overlap in red and blue](https://www.thetransmitter.org/wp-content/uploads/2020/01/20200131-RRBExplainerV2844.jpg)
Repetitive behaviors and ‘stimming’ in autism, explained
Restricted interests and repetitive behaviors constitute one of two criteria that define autism in the diagnostic manual for psychiatry.
Sleep problems in autism, explained
Many people with autism have difficulty falling and staying asleep, but there may be ways to help them.
![Illustration shows child's head, with an EEG background, and a sleeping figure floating in the clouds above his head.](https://www.thetransmitter.org/wp-content/uploads/2020/02/Sleep-844.jpg)
Sleep problems in autism, explained
Many people with autism have difficulty falling and staying asleep, but there may be ways to help them.
Social communication in autism, explained
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.
![silhouette of head with illustrated text](https://www.thetransmitter.org/wp-content/uploads/2018/04/1120x550_lead_05_lowres.jpg)
Social communication in autism, explained
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.
The link between epilepsy and autism, explained
Autism and epileptic seizures often go hand in hand. What explains the overlap, and what does it reveal about autism’s origins?
![a human brain model made of springs is shaking on its spring base](https://www.thetransmitter.org/wp-content/uploads/2019/10/20190921Epilepsy844.jpg)
The link between epilepsy and autism, explained
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
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.
![](https://www.thetransmitter.org/wp-content/uploads/2018/07/20180725-Comorbid844.jpg)
Conditions that accompany autism, explained
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.
Autism’s sex ratio, explained
More boys than girls have autism; diagnostic biases and genetic factors may explain the skewed sex ratio.
![Female head shape cut out of pink paper, under magnifying glass. Male head is in blue, opposite the female.](https://www.thetransmitter.org/wp-content/uploads/2018/06/sexbias844.jpg)
Autism’s sex ratio, explained
More boys than girls have autism; diagnostic biases and genetic factors may explain the skewed sex ratio.
Motor difficulties in autism, explained
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 showing two hands plugging cables into different areas of the brain, eg. prefrontal cortex, motor cortex, etc.](https://www.thetransmitter.org/wp-content/uploads/2020/08/MotorExplainer844.jpg)
Motor difficulties in autism, explained
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.
Gender and sexuality in autism, explained
Gender and sexuality appear to be more varied among autistic people than among neurotypical people. What do scientists know about the connection?
![Illustration of hand pressing one orange button on a keyboard with keys of various colors.](https://www.thetransmitter.org/wp-content/uploads/2020/09/20200918-GenderExplainer-844.jpg)
Gender and sexuality in autism, explained
Gender and sexuality appear to be more varied among autistic people than among neurotypical people. What do scientists know about the connection?
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Skeptics challenge claims of Alzheimer’s disease transmission via growth hormone
Some people who received cadaver-derived human growth hormone may not have Alzheimer’s as previously suggested, according to a new Perspective article.
![Colored transmission electron micrograph (TEM) showing an amyloid plaque in a brain with Alzheimer’s disease.](https://www.thetransmitter.org/wp-content/uploads/2024/08/Transmissible-Alzheimers-neuro-1200-1024x683.webp)
Skeptics challenge claims of Alzheimer’s disease transmission via growth hormone
Some people who received cadaver-derived human growth hormone may not have Alzheimer’s as previously suggested, according to a new Perspective article.
Neurons’ spikes may convey their whereabouts
The time lag between spurts of activity holds anatomical information, according to a preprint.
![Illustration of a neuron with cardinal directions superimposed over it as on a compass.](https://www.thetransmitter.org/wp-content/uploads/2024/08/compass-neuron-1200-1024x692.webp)
Neurons’ spikes may convey their whereabouts
The time lag between spurts of activity holds anatomical information, according to a preprint.
Task swap prompts data do-over for autism auditory perception study
The investigators retracted their paper after other researchers pointed out the error; the original team plans to redo the experiment, according to one author.
![Illustration of a red pencil with a white eraser that is being used against a white sheet of paper.](https://www.thetransmitter.org/wp-content/uploads/2024/08/correction-1200-1024x692.webp)
Task swap prompts data do-over for autism auditory perception study
The investigators retracted their paper after other researchers pointed out the error; the original team plans to redo the experiment, according to one author.