People are currently diagnosed with autism
when they have a triad of traits – impaired
social ability, difficulties with communication,
and restricted and repetitive behaviour. But
are all three characteristics inextricably linked?
Dr Francesca Happé thinks not: studies of people
with autism and their relatives over almost two
decades have led her and her colleagues to
believe each of the three features of autism
are caused by largely independent genes, are
associated with different brain regions and are
related to different cognitive characteristics.
A Cognitive Psychologist, DrHappé has
spent some 20 years trying towork out
why people with autismview the world
so differently. ‘People with autism have
striking social difficulties,’ she said. ‘They find
it hard to recognise other people’s thoughts and
feelings. At the same time, they have superior
cognitive processing in terms of eye for detail.
We have been looking at the underlying causes
of these different aspects of autism, searching
for a parsimonious explanation, but try as
we might, we have been unable to find one.’
So instead of continuing to search for a
single cause of autism, they are now trying
to understand more about what causes the
three individual characteristics, and why
they co-occur. To this end, DrHappé and
her IoP colleague Professor Patrick Bolton
have launched the largest ever communitybased
twin study of the autism spectrum
with the help of 300 families who are part
of the IoP-based TwinsEarlyDevelopment
Study (TEDS). Using information gathered
from TEDS families, DrHappé, Dr Angelica
Ronald and colleagues have already found a
considerable number of children who have
difficulties in only one area of the autistic
‘triad.’What’s more, the comparison of the
development of identical and non-identical
TEDS twins when they were aged seven and
eight suggests that, while each different aspect
of the triad is highly heritable, separate genes
contribute to each individual trait. ‘It looks
as if largely independent genetic influences
operate on the three different traits,’ said
DrHappé. ‘If this is correct, the search for
genes ‘for’ autism may be far less effective
than searching for genes affecting, for example,
social skills specifically, or those contributing
to rigid and repetitive traits.’
This conclusion has been supported by
other studies that illustrate how individual
traits run in families of people with autism –
close family members often share just one of
the triad of traits, to a lesser or greater degree.
‘Many fathers of children with autism in
particular show the same sort of focus on detail,
rather than the bigger picture,’ she said, ‘and
social difficulties can also be found in family
members whomay not show an eye for detail.’
If the theory is correct, she says, many
individuals may possess one characteristic
of the triad, but do not meet the diagnostic
criteria for autism. ‘There may be people
who have pretty poor social skills, but have
no problems with communication, or people
who are able socially, but have rigid and
repetitive behaviour.’
The newMedical Research Council-funded
twin study seeks to find out more about the
causes of the triad’s individual traits as well
as their interaction in autism. 200 of the
participating families have at least one twin
with a diagnosis on the autism spectrum.
‘We will be visiting families and interviewing
them about symptoms and current functioning,
asking about childhood illness and other health
problems in order to identify environmental
factors that may have played a part, and
undertaking cognitive testing of the twins
to look for different psychological processes
that underpin the triad traits.’
The TEDS twins are now aged between 12
and 14. ‘Because we have information about
them that families and teachers gave when
they were younger, we will be able to check
back for precursors to the development of
the characteristics during the early years,’
she said. The researchers will eventually
use the information they gather to help
search for genetic, environmental and
cognitive influences underlying each
of the individual features.
‘What we want to do is to understand
how the triad hangs together in autism,’
she said. ‘Most importantly, as we abandon
the search for a single cause for autism
and increase our understanding of the
three distinct characteristics, we may
need to abandon the search for a single
“cure†for autism, and instead tackle the
individual traits of the triad.’
| Autism spectrum disorder | 15
Separating the triad of autismtraits
‘Research suggests separate genes
contribute to each individual trait’
When I found out I was pregnant in
1998, I was over the moon,’ says Angie
Perks. ‘Then I had a scan, which confirmed
that I was having twins. At 37 weeks, I gave
birth by C-section to Kylie, who weighed
5lb 9oz, and then Thomas who was 6lb 3oz.
‘By 14 months, Kylie was walking and talking.
At 18 months, Thomas finally began to walk,
but he never played with his twin sister and
wasn’t talking, so I asked my health visitor
who was also concerned about him. She
got in contact with the child development
centre and a lady came to see us. Penny
came to our house to watch Thomas.
I remember he was sat on the floor lining
his bricks in a row and making sounds. She
sat writing in her book then she looked at
us and said, “I think Thomas may have autism.â€Â
I actually had an idea that she might say that
as I had looked on the internet and came
across this website which explained to me
what the symptoms were. After an assessment
at hospital, Thomas was diagnosed with severe
autism. The twins are now nine, and Thomas
is still non-verbal and still in nappies. He can
be destructive and it is sometimes hard
work looking after him and making sure
Kylie doesn’t lose out. My mum helps a lot
and Kylie has now started going dancing
and has some shows coming up, though
Thomas won’t be able to sit through them.
‘Thomas goes to a really good special
school and they write me a letter every
day to say what he’s done as he can’t tell
me. He loves his routine and he stays in
his room for hours and hours. Kylie is his
big sister and always will be. When other
children ask her about her brother,
she tells them he’s got autism and
what that means. Children can be
cruel, and if they don’t understand,
she doesn’t want to know them.
‘People don’t realise they are twins
because they are nothing alike at all. They
look different and they have completely
different personalities. I used to be really
upset at the stares that Thomas would get,
but now I just take no notice. People just
see him as a naughty boy. They really
don’t understand about autism, and
they certainly don’t understand why
one twin can have it and the other not.
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