Saturday, 19 January 2013

Sex differences in autism presentation

I've been thinking quite a bit about the paper by Lai and colleagues* (open-access) looking at cognition between the sexes with autism in mind. They concluded that "ASC [autism spectrum conditions] varies with sex in some non-social cognitive domains, although not in relation to the core social cognitive difficulties".

Fair enough, there is overlap across the sexes with the characteristics of autism in mind, but potentially some other important differences, bearing in mind that I'm not really a great fan of the grand sex-gender divide when it comes to the brain and behaviour and autism (look up Cordelia Fine for a good critique).
Lamps @ Wikipedia 

The Lai paper did however get me searching around for some of the other literature on sex differences when it comes to autism, in terms of things like identification which forms the bulk of this post.

I might add that I've touched upon this important topic previously in terms of the sex ratio (see here) and savant abilities (see here) but consider this post to be slightly different as a few papers are considered including the one from Begeer and colleagues** and the one from Mandy and colleagues***.

So without further ado a few choice points from the papers:

The Begeer paper.

  • Based on responses for quite a large sample size (N=2275) of children and adults with an autism spectrum disorder, a 53-item survey questionnaire was used to ascertain various experiences of diagnostic procedures, treatment, schooling and employment.
  • The aim of the study was to analyse the questionnaire responses based on the hypothesis that there might be differences in identification and diagnostic experiences of females with autism over males.
  • The results: the mean time between first signs and symptoms of autism appearing and identification was longer for girls (2.3 years vs. 1.9 years) than boys. The authors comment on how this figure is slightly fuzzy based on the numbers of cases of autism being diagnosed in adulthood.
  • When data were separated based on children (0-18 years) and adults (18-85) (I assume that there was criteria for those people who were actually 18 years old), girls were almost 2 years delayed in getting a diagnosis of Asperger syndrome over boys.

The Mandy paper.

  • An interesting study aiming to "investigate the female ASD phenotype amongst predominantly high-functioning children and adolescents".
  • Three hundred and twenty five children with ASD (aged between 3-18 years), comprising 52 girls, were included for study based on referrals to a specialist clinic for the assessment of "high-functioning children with social communication difficulties".
  • A variety of assessment schedules were used including the 3di**** (developed by this author group) and the ADOS, complemented by measures of intelligence (IQ).
  • Results:  there were quite a few 'no differences' detected between the sexes in things like verbal and performance IQ. Core symptom presentation-wise, the new social affect superdomain likewise showed no significant differences across the sexes. Same goes for various peripheral signs and symptoms in terms of things like feeding and sleeping.
  • When it came to repetitive stereotyped behaviours (RSB), there were some differences between the sexes reflective of "milder RSB amongst females with ASD". That and females generally showing better fine motor skills; something which was pretty stable across the age-ranges of this cohort.
  • The authors conclude that a milder presentation of things like RSB might be part and parcel of under-recognition of autism in females and indeed that girls might be better at 'compensating' for their difficulties in certain situations.

Based on these collective works, there are some potentially important points to take home. That there may be a disparity between the sexes in terms of the age of getting a diagnosis (and I assume access to appropriate services) is perhaps the most important issue. Given the strong inclination towards males presenting with autism, one could argue that our screening and assessment radar is already biased in favour of picking up autism spectrum disorders in boys. That being said, don't think that it is always easy to get an assessment for boys either as per the paper by Ryan and Salisbury***** and the sentiments of 'you know what boys are like' covered in another post.

The potential reason for disparity in getting a diagnosis? The RSB domain differences are seemingly important as per the Mandy findings. Indeed looking closer at the individual items within the RSB domain, its evident that two main driver characteristics seem to be more present in boys than girls in their cohort: (a) possessing a large factual store of information and (b) oddly formal play (so for example ordering toys, etc.). So then outside of little differences in core social affect (communication and social interaction), the question is whether the strong presence, or indeed weak presence, of these behaviours is enough to red flag boys and girls at similar times?

Of course, one has to be cautious about becoming too formulaic about sex differences in autism
bearing in mind little interfering variables like comorbidity and indeed the heterogeneity that is evident across the entire autism spectrum. The future of such sex differences is also likely to be further complicated as and when the new DSM (and ICD) criteria are eventually agreed upon and published and whether, because of the various changes proposed, the same, more or less children across the sexes are likely to fit into the new developmental boxes.

And finally, the last of the famous international playboys?


* Lai MC. et al. Cognition in males and females with autism: similarities and differences. PLoS One. 2012; 7: e47198.

** Begeer S. et al. Sex differences in the timing of identification among children and adults with autism spectrum disorders. J Autism Dev Disord. September 2012.

*** Mandy W. et al. Sex differences in autism spectrum disorder: evidence from a large sample of children and adolescents. J Autism Dev Disord. 2012; 42: 1304-1313.

**** Skuse D. et al. The developmental, dimensional and diagnostic interview (3di): a novel computerized assessment for autism spectrum disorders. J Am Acad Child Adolesc Psychiatry. 2004; 43: 548-558.

***** Ryan S. & Salisbury H. 'You know what boys are like': pre-diagnosis experiences of parents of children with autism spectrum conditions. Br J Gen Pract. 2012; 62: e378-383.

---------- Begeer S, Mandell D, Wijnker-Holmes B, Venderbosch S, Rem D, Stekelenburg F, & Koot HM (2012). Sex Differences in the Timing of Identification Among Children and Adults with Autism Spectrum Disorders. Journal of autism and developmental disorders PMID: 23001766

Mandy W, Chilvers R, Chowdhury U, Salter G, Seigal A, & Skuse D (2012). Sex differences in autism spectrum disorder: evidence from a large sample of children and adolescents. Journal of autism and developmental disorders, 42 (7), 1304-13 PMID: 21947663