Sunday, 10 April 2011

Is autism the same all over the world?

Modern human beings, homo sapiens sapiens. A term which unites us all because it reflects us all.

Move however further across the biological and ethnic sub-categorisations of homo sapiens sapiens and we slowly begin to differentiate ourselves from each other on the basis of gender and race. Further across, and including some societal, cultural and individual 'personality' differences mixed in with experience and environment, and we go from all being one and the same to all being uniquely different.

You could probably apply the same logic to anything. Start with a generic term, say 'autism spectrum condition' as described in the proposed DSM-V manual; move across the various categorisations, say sub-diagnosis, then move further across societal and individual differences et al and hey presto, unique and one-of-a-kind.

The reason for such a grandiose beginning to this entry is to show how similarity and differences can often be influenced by the level of description and semantics used.

Autism is defined by DSM and ICD diagnostic listings. This means that wherever in the world a child or adult is diagnosed, theoretically they should be similar in terms of the presentation of core symptoms fulfilling the diagnostic criteria. But does this guarantee that presentation and pathology of autism is the same the world over?

I was brought to this question by an article appearing recently suggestive that Israeli children with autism do not appear to show the same trend of macrocephaly as has been described in other studies from other parts of the world. The authors of the Israeli study attribute this difference to 'a different genetic background'. I know macrocephaly is not a core trait of autism but it got me thinking. What other research has been done on the similarities/differences between autism populations around the world, and in particular on the presentation of symptoms?

Well cryptically quite a bit and not very much at all. I will explain.

Ethnicity, and the other societal factors associated with ethnicity, has been quite extensively studied in autism. We know that although not uniform, certain ethnic groups not indigenous to a specific country tended to be under-represented in cases of autism. Take for example this study from the Netherlands which suggested if you were White European (by both parents), you were more likely to diagnosed with autism than if one or both of your parents were non-European. This tends to follow similar trends from research outside of autism.

An ethnic reason, genetic reason, environmental reason or a cultural reason?

There is also a suggestion that 'risk' of autism may be greater where mums are, for example, born in parts of Asia when compared to indigenous Australian parents with European heritage according to this study; following on from more recent suggestions of increased risk of autism in Somali populations.

Fine, but what about those who already have been diagnosed?

Well this is where the research dries up a little. There is a little about presentation of autism in various countries outside of the main research-bearing nations; so we have papers from Saudi Arabia for example describing autism in Saudis. There are no doubt other examples from other countries.

Very little has however been produced in the way of comparing country against country or ethnicity against ethnicity on symptom presentation. Those few studies that have been performed on this issue suggests some minor differences (language?) but nothing concrete, and tend to be plagued by methodological issues such as low participant numbers for example.

Would it be so difficult to look at 500 people with various autism diagnoses from each of the 5 (inhabited) continents (n=2500) and compare and contrast, using the array of questionnaires, schedules and observation tools on offer in autism research, their core and peripheral symptoms? Too much...?

If they were all (roughly) the same, fine - we have confidence that autism is (roughly) globally the same. If they were different though, what would that suggest?