Comorbidity Williams syndrome and Autism spectrum disorders

Comorbidity Williams syndrome and Autism spectrum disorders

 

Comorbidity is the presence of a developmental disorder co-occurring with another one. It is often claimed that those with Williams syndrome (WS) and those with Autism spectrum disorders (ASD) show opposite social and communication difficulties. Yet, the comorbidity between WS and ASD is higher than expected, even though the exact rate of dual diagnosis is currently unclear. A number of parents have asked me how a comorbid diagnosis for ASD in WS can be made. Therefore, below I have outlined some of the similarities and differences that are commonly observed in those with WS and ASD (but this list is not exhaustive). Although all children are different, these are the typical behaviours that one would observe for each developmental disorder. As you can see from the table, there is quite a lot of overlap between the two disorders, which makes it harder to make a comorbid diagnosis of ASD and WS.

 

ASD	WS
Similarities
Delayed verbal abilities (delayed first word)	Delayed verbal abilities (delayed first word)
Poor grammatical comprehension	Poor grammatical comprehension
Takes language literally	Takes language literally
Sensory processing difficulties	Sensory processing difficulties
Likes repetition and structure	Likes repetition and structure
General anxiety	General anxiety
Delayed motor development	Delayed motor development
Local processing bias	Local processing bias
Differences
Good visuo-spatial abilities (puzzles)	Poor visuo-spatial abilities (puzzles)
High social anxiety	Low social anxiety
Low social approach	High social approach
Eye contact avoidance	Eye contact seeking/ staring at faces
Stereotyped language	Some stereotyped language but less
Atypical intonation	Generally typical intonation
Echolalia	Some echolalia but limited
Does not respond to name	Responds to name
Poor imaginary play	Good imaginary play

 

As can be seen from the table children with WS often show socio-communication difficulties that overlap with ASD. However, those with WS who receive a dual diagnosis for ASD show more features that are typically only seen in ASD, especially eye contact avoidance, atypical intonation, and low social approach.

 

Further reading

 

Klein-Tasman BP, Phillips KD, Lord CE, Mervis CB, Gallo F. Overlap with the Autism Spectrum in Young Children with Williams Syndrome. Journal of developmental and behavioral pediatrics : JDBP. 2009;30(4):289-299. doi:10.1097/DBP.0b013e3181ad1f9a.

 

Asada K, Itakura S. Social Phenotypes of Autism Spectrum Disorders and Williams Syndrome: Similarities and Differences. Frontiers in Psychology. 2012;3:247. doi:10.3389/fpsyg.2012.00247.