Synaesthesia

Posted on Autism

Synaesthesia may be ‘more common’ in autism

Synaesthesia
Synaesthesia

“Study links synaesthesia to autism,” BBC News reports. The news comes from the results of a small study that suggests that synaesthesia is more common in adults with autism (also known as autistic spectrum disorder).

Synaesthesia is a condition where experiencing one sensation in one of the senses, such as hearing, involuntarily triggers another sensation in another sense, such as taste. An example given in the study for one person is that every time they heard the word “hello” they experienced the taste of coffee.

The researchers explain that synaesthesia has been estimated to affect around 4% of the population and autism 1% of the population. If the two phenomena were completely independent, you’d expect to see the same prevalence of synaesthesia in people with and without autism.

However, this study, which involved screening people with and without autism for synaesthesia, showed this may not be the case. In adults with autism, the prevalence of synaesthesia was estimated to be 18.9%, whereas adults without autism had a much lower prevalence of 7.21%.

The study’s results appear broadly reliable, but they need to be confirmed in larger studies to be sure. If true, these findings imply that the two conditions may share some common cause in the brain.

The researchers speculate that both conditions may be associated with what they term “hyperconnectivity”, or excessive neural connections between different parts of the brain.

Further research using technology such as functional MRI scanners may be able to provide more information about the biological link between the two conditions.

Where did the story come from?

The study was led by researchers from the Autism Research Centre at the University of Cambridge. The various collaborating authors involved in the work were funded by the National Institute for Health Research, the Gates Foundation, the Medical Research Council UK, and the Max Planck Society.

The study was published in the peer-reviewed science journal Molecular Autism.

BBC News’ reporting of the study was good quality. It provided an accurate overview of the research and included some useful quotes from the researchers involved as well as independent experts. 

What kind of research was this?

This was a cross-sectional study looking at whether synaesthesia was more common in people with autism.

Synaesthesia is a condition where one sensation triggers a perception of a second. For example, a person could taste numbers or hear colours. Self-reported examples of this from the study include how “the letter q is dark brown”, “the sound of the bell is red”, and “the word hello tastes like coffee”.

Autism is shorthand for autistic spectrum conditions, which are a range of related developmental disorders, including autism and Asperger’s syndrome. They share some features, such as difficulties with social communication, resistance to change, and a focus on an unusually narrow range of interests or activities, but the level of difficulties faced varies between individuals.

People with Asperger’s syndrome have fewer problems with language, are often of average or above-average intelligence, and are usually high functioning and able to live independently.

Some people, the researchers report, have suggested that synaesthesia and autistic spectrum conditions may originate from brain abnormalities common across both conditions. This led the researchers to investigate whether synaesthesia was more common in people with autism to see if the two conditions appeared to be related.

A cross-sectional study is an appropriate way of assessing the prevalence of something in a group of people, such as estimating what proportion of people with autism experience synaesthesia. However, this type of study cannot prove that the two conditions are biologically linked.

What did the research involve?

A group of 927 adults with autism and 1,364 adults without autism were invited to participate in the study. Of these, 164 adults with clinically diagnosed autism and 97 adults without the condition took part.

Both groups completed online questionnaires assessing any experiences of synaethesia, as well as their autistic traits to check on the original autism diagnosis.

A third test was used to investigate the consistency of the participants’ synaesthetic experiences and to further check that they were reporting genuine experiences. This consistency test involved “matching” words or sounds to preferred colours.

Conservative inclusion criteria were reported to be used to judge if an individual had synaesthesia. For example, if synaesthesia was first experienced in adulthood, the person was judged not to have synaesthesia.

To be considered synaesthetic, participants had to report that they experienced synaesthesia and could not meet any of the exclusion criteria. Exclusion criteria included people who had medical conditions affecting their vision, the brain, or who had a history of hallucinogenic drug use. This was to ensure that their synaesthetic experiences were not as a result of injury or drug use.

The analysis compared the prevalence of synaethesia in people with autism with people without the condition.

What were the basic results?

Of the 164 people in the autism group, 31 were considered synaesthetic, a rate of 18.9%. Synaesthesia in the control group was significantly lower, at 7 out of of 97 people, or 7.21%.

Most of the autism group had Asperger’s syndrome (03%), nine (5.5%) had higher-functioning autism, and two (1.2%) had pervasive developmental disorder (not otherwise specified).

No group differences were found in age or education, with the latter measured by the rate of university attendance.

Hardly anyone filled in the consistency questionnaire, so it was not possible for the researchers to obtain results from this. Further investigation revealed that people with autism were fatigued from the 241 possible choices during this test, so gave up before completing it.

How did the researchers interpret the results?

The researchers concluded that, “The significant increase in synaesthesia prevalence in autism suggests that the two conditions may share some common underlying mechanisms. Future research is needed to develop more feasible validation methods of synaesthesia in autism.”

Conclusion

This small study suggests that synaethesia is more common in adults with autism than in adults who do not have the condition. Prevalence in a group mainly diagnosed with Asperger’s syndrome was estimated at 18.9%, compared with 7.21% in adults without autism, using a sample of 261 people in total.

In spite of these interesting findings, the study has several limitations:

  • The study sample was relatively small for a prevalence study. A study using more people would produce more reliable estimates and would be able to confirm or refute these initial findings.
  • The study participants with an autistic spectrum disorder mainly had Asperger’s syndrome, which is at the higher functioning end of the spectrum, with only two people having potentially greater impairment. The results cannot be generalised to all people with autism.
  • The researchers were unable to collect completed consistency tests to validate the prevalence estimates of synaesthesia. They report that the traditional test to confirm symptoms may not be suitable for people with autism.
  • The study did not recruit children, so it is not clear if similar findings would be discovered earlier in life.
  • It is not clear how representative the “control” group of adults without a diagnosis of an autistic spectrum disorder was of the general population. It was a small sample size, and it is not clear what their motivations were for completing the questionnaires. What is interesting is that 27 respondents without a formal diagnosis of autism were excluded from the study because their answers to the autism questionnaire indicated that they might be on the spectrum.
  • The criteria for assessing whether someone was synaesthetic or not weren’t wholly clear. Using a stricter or looser definition to categorise synaesthesia would change the estimates of prevalence reported.
  • The study does not tell us about the biological underpinnings of synaesthesia or what they may or may not have in common with autism.
  • The study didn’t seem to account for the possibility that some people with psychosis might report experiences that could be falsely categorised as synaesthetic. However, the impact of this possibility is likely to be very small.

In considering the results, it is important to realise that synaesthesia is not necessarily an impairment and in some cases can enhance memory or creativity.

The bottom line is that this study suggests synaesthesia is more prevalent in adults with autism than non-autistic adults, but this needs to be confirmed in bigger studies to be more certain.

If true, the implication of this finding is that the two conditions may share some common causes in the brain, but this is not yet proven.

The researchers argue that investigation into the possible links between the two conditions using more sophisticated techniques such as MRI scans is now a research priority.

Analysis by Bazian
Edited by NHS Website

Leave a comment Posted on Autism

Synaesthesia may be ‘more common’ in autism




Synaesthesia

Synaesthesia

“Study links synaesthesia to autism,” BBC News reports. The news comes from the results of a small study that suggests that synaesthesia is more common in adults with autism (also known as autistic spectrum disorder).




Synaesthesia is a condition where experiencing one sensation in one of the senses, such as hearing, involuntarily triggers another sensation in another sense, such as taste. An example given in the study for one person is that every time they heard the word “hello” they experienced the taste of coffee.

The researchers explain that synaesthesia has been estimated to affect around 4% of the population and autism 1% of the population. If the two phenomena were completely independent, you’d expect to see the same prevalence of synaesthesia in people with and without autism.

However, this study, which involved screening people with and without autism for synaesthesia, showed this may not be the case. In adults with autism, the prevalence of synaesthesia was estimated to be 18.9%, whereas adults without autism had a much lower prevalence of 7.21%.

The study’s results appear broadly reliable, but they need to be confirmed in larger studies to be sure. If true, these findings imply that the two conditions may share some common cause in the brain.

The researchers speculate that both conditions may be associated with what they term “hyperconnectivity”, or excessive neural connections between different parts of the brain.

Further research using technology such as functional MRI scanners may be able to provide more information about the biological link between the two conditions.




 

Think you have synaesthesia?

If you suddenly begin to experience symptoms of synaesthesia for the first time, you should seek medical advice. There could be underlying factors related to your brain and nervous system that may require further investigation.

Where did the story come from?

The study was led by researchers from the Autism Research Centre at the University of Cambridge. The various collaborating authors involved in the work were funded by the National Institute for Health Research, the Gates Foundation, the Medical Research Council UK, and the Max Planck Society.

The study was published in the peer-reviewed science journal Molecular Autism.

BBC News’ reporting of the study was good quality. It provided an accurate overview of the research and included some useful quotes from the researchers involved as well as independent experts.

 

Leave a comment Posted on A to Z of Medical Conditions

Synaesthesia – so what actually is Synaesthesia ?




Synaesthesia

Synaesthesia

Introduction




Synaesthesia is a condition where a sensation in one of the senses, such as hearing, triggers a sensation in another, such as taste.

For example, some people with synaesthesia can taste numbers or hear colours.

A wide range of different synaesthetic experiences have been reported and recorded – a typical example is someone who described experiencing the colour red every time he heard the word “Monday”.

What are the different types of synaesthesia?

There are many different types of synaesthesia, and many people with synaesthesia will experience more than one of these – for example, taste, sound and touch may all produce colours.

Colours and patterns

Research suggests that the most common synaesthetic experiences are associating days, months, numbers and the alphabet with:

patterns or shapes (for example, envisaging the months laid out in lines, spirals or circles)

distinctive colours – for example, “A” may be red and “B” may be blue

Synaesthesia affects people differently. Two people with synaesthesia will often disagree over the colour of letters.

However, there are some trends that appear common to all people with the condition – A is generally perceived as red, B is often blue, and C is often yellow.

Taste and smell





For some people with synaesthesia, spoken words trigger a particular taste, as well as a particular texture, place in the mouth and temperature (for example, “runny egg yolk”).

Taste can also produce colour sensations, or shapes that can be “felt”.

Certain odours may also be perceived as shapes and/or colours, but this form of synaesthesia is thought to be rare.

Touch and other body sensations

Some people experience touch just by looking at someone being touched. This is known as “mirror touch” synaesthesia.

Feelings of pain or touch can also trigger visions or colour, and there has been a documented case of words triggering feelings of body movement.

Advice for people with synaesthesia

Most people with synaesthesia have had it since childhood, so it feels perfectly normal to experience the world in this way. It’s not obtrusive and does not affect day-to-day life. It’s not necessary to see a doctor.

If you think your child has synaesthesia

If you are a parent of a child with synaesthesia, you may wish to discuss it with their teacher so they are aware of it. There is evidence that synaesthesia affects educational ability, either by slightly distracting the pupil, or (most often) by giving slight learning advantages.

It may also be true that your child will learn in different ways to other children. For instance, many people with synaesthesia report a visual style of thinking.

If it comes on suddenly in adulthood

If you suddenly begin to experience symptoms of synaesthesia for the first time as an adult, it’s a good idea to see your GP for an assessment.

This is because there could be underlying factors related to your brain and nervous system that may need investigating.

Is synaesthesia linked to other conditions?

Because the number of people with synaesthesia is relatively small, it is not yet possible to know this conclusively.

An Australian study did not find any evidence of an association between synaesthesia and various mental health problems. In fact, there is growing evidence that synaesthesia may be linked to certain advantages, including enhanced memory, superior perception and being able to think more quickly.

Two small studies published in 2013 suggest that synaesthesia is more common in adults with autism (also known as autistic spectrum disorder) than in adults who do not have an autistic spectrum disorder.

The studies involved screening people with and without autism for synaesthesia. In adults with autism, the prevalence of synaesthesia was estimated to be 17-19%, whereas adults without autism have a much lower prevalence of 2% (for more information, read NHS News: Synaesthesia may be ‘more common’ in autism).

These results appear broadly reliable, but they need to be confirmed in larger studies. If true, these findings imply that the two conditions may share some common cause in the brain.

However, it’s important to note that most people with autism do not have synaesthesia, and that most people with synaesthesia do not have autism.

What’s the cause?

It’s likely that the brain of someone with synaesthesia is “wired” differently, or has extra connections.

A brain imaging study has shown that when some people with synaesthesia hear spoken words, a part of their brain normally used to process colour from vision lights up.

Synaesthesia runs in families, although it may skip a generation and may not affect immediate relatives. It’s possible for only one twin to have the condition, or for family members to show different types of synaesthesia. In summary, there is a genetic contribution to synaesthesia, but the environment is also important.

It’s possible for people to “grow out of” synaesthesia: there have been cases of people claiming that they used to experience synaesthesia, but no longer do.

How do people with synaesthesia feel about their condition?

Interviews with people who have synaesthesia show a wide range of feelings towards their condition.

Many are positive about it (“I feel sorry for people who don’t have this”), and can’t imagine their life without it.

Some feel neutral about it, and treat it as something they’ve become used to, which doesn’t affect them in any way.

For a minority, the sensations can disrupt their chain of thought and be intrusive.

How common is it?

Synaesthesia has been estimated to affect at least 4% of the UK population.

Researchers at the University of Sussex have estimated that 1-2% of the UK population experience colour when they see, hear or think about letters and numbers, and that synaesthesia is just as common in women as in men (read the study).