Okay, so this distinction is important. I spoke recently to a Neurodevelopmental Specialist who, amongst other things, teaches psychologists how to diagnose ASD under DSM5. And @snavej is right, ‘High Functioning’ or ‘Low Functioning’ as specified on an ASD diagnosis is a descriptor simply denoting whether or not the individual in question tested above or below 70 on an IQ test.

This is a problem for several reasons. One, as @my-autistic-things pointed out, IQ is actually a terrible way to measure intelligence. It measures very specific things and doesn’t really indicate anything more than whether or not someone is good at IQ tests.

The far bigger problem is that the majority of healthcare professionals do not seem to be aware that this is what the ‘High or Low Functioning’ label means (likely as a result of the term functioning being used differently in other contexts, such as depression etc.).

This means that a label such as ‘High Functioning’ which was given to mean ‘Without Intellectual Disability’ is interpreted as ‘An individual who is able to function independently in society’.

This is such an important distinction, because ‘High Functioning’ autistic people are frequently denied the support they need because the healthcare services misunderstand the label, and ‘Low Functioning’ autistic people are often denied autonomy in their care and lives because of the same misunderstanding.

So if I’m to make a point it’s this. There needs to be more clarity in what these terms mean. Long term this could mean replacing functioning labels with something that is clearer in what it means, but this is unlikely to be possible until DSM6 is published. In the meantime it means being aware of this ourselves. Because whether or not your IQ score is over 70 has no bearing on whether or not you require support in your day to day life.