Sotos Syndrome: A Summary of the Research
Introduction
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| Lead researcher: Chloe Lane |
Sotos syndrome was first recognised as a
syndrome in 1964. Since this time, several studies have investigated cognitive
and behavioural features of the syndrome. Cognition has been reported in terms
of level of intellectual functioning, as well as more specific abilities such
as language. A number of behavioural issues have been identified in some
individuals with Sotos syndrome. These include autism spectrum disorder,
anxiety and ADHD. The purpose of this review was to identify and summarise all
of the research that has reported information about cognition and behaviour in
individuals with Sotos. A summary of all of the existing research is helpful in
providing an overview of what is currently known about these aspects of the
syndrome.
Method
Academic databases were systematically
searched to identify all of the research that has reported information about
Sotos syndrome. The search yielded 917 results and these were checked in order
to identify research that provided information about cognition or behaviour in
Sotos syndrome. After screening all of these articles, 34 papers were
considered relevant for the review. Below is a brief summary of each of the
main findings from the review.
Intelligence
Quotient (IQ)
Several studies (25) have measured IQ in
individuals with Sotos syndrome. IQ scores are obtained by administering a
series of tasks that measure cognitive abilities such as memory, language and
reasoning. IQ scores are calculated by taking into account performance on each
of the individual tasks. The scores therefore provide an indication of the
general level of intellectual functioning of an individual. An IQ score of 100
is the average score for the general population. Scores in the range of 70 – 84
are considered to be in the borderline range and scores below 70 indicate that
an individual has a learning disability. The existing research suggests that
the majority of individuals with Sotos syndrome have a mild learning disability
or are in the borderline range. However, scores that have been reported within
these studies have ranged from 21 – 113, indicating that intellectual ability
in individuals with Sotos can range from severe learning disability to above
average cognitive ability.
Language
Language abilities have been
investigated in 13 studies. The findings from these studies suggest that
language abilities are consistent with general level of intellectual
functioning. This means that if a child with Sotos has a mild learning
disability, their language skills will likely be at the same level as would be
expected from any other child with a mild learning disability. Children with
Sotos may display speech and language delays and experience greater difficulty
with expressive, compared to receptive language. This means that they are
likely to have a good understanding of language but have difficulty
communicating and expressing ideas.
Aggression
and Tantrums
Aggressive behaviour and tantrums have
been reported in a small number of studies (6). All of the participants in
these studies were children with Sotos syndrome. Although these issues have
been reported in several children with Sotos, it is not clear whether these
issues are specifically linked to Sotos. One suggestion is that children with Sotos
may become frustrated as they are often larger than their peers and therefore
mistaken as being older or more able than their actual developmental level.
Autistic
Features
Four studies have reported individuals
with Sotos syndrome who also have a diagnosis of autism spectrum disorder
(ASD). This suggests that there may be an association between Sotos and ASD but
this has not been explored in detail.
Attention
Deficit Hyperactivity Disorder (ADHD)
ADHD may be another common behavioural
issue associated with Sotos syndrome. Eight studies have investigated ADHD in
Sotos syndrome and several individuals were reported to meet criteria for a
diagnosis of ADHD. In addition, a small number of individuals were described as
being inattentive, hyperactive or demonstrating a lack of inhibition. These are
all symptoms that are commonly associated with ADHD.
Anxiety
Two studies have investigated anxiety in
individuals with Sotos syndrome. The existing research suggests that anxiety
may be a common issue associated with Sotos syndrome. Specifically, it seems
that individuals with Sotos are likely to display separation anxiety (anxiety
provoked by separation from a parent or caregiver), be anxious in new situations
and have some form of phobia.
Conclusion
To date, a total of 34 studies have provided
insight into the cognitive and behavioural features of Sotos syndrome. The
common themes arising from the review are explained above. As much of the
existing research is based on small samples of children with Sotos, it will be
important for future research to investigate cognition and behaviour in larger
groups of individuals with Sotos. This will be beneficial in identifying what
to expect from a child with Sotos. In addition, it will be important to
investigate cognition and behaviour in adults with Sotos as very little is
currently known about cognitive abilities and behavioural issues in adults with
Sotos.
For the full paper, please see:
Lane, C., Milne, E. & Freeth, M.
(2016). Cognition and Behaviour in Sotos Syndrome: A Systematic Review. PLoS
ONE.
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