What have you been working on?

A study on language impairment at school entry age, and how we can better identify, diagnose and treat language disorders.

Using a sample of 7,267 state school children in Surrey, we assessed language, non-verbal IQ (NVIQ), social, emotional, and behavioural problems among 529 pupils aged 5 to 6.

The study also compared the severity of language disorders in children with both average and low-average NVIQ.

What have you found?

On average, about two children in every year 1 class have a clinically significant language disorder that impacts their learning.

This means that language disorders are about seven times more prevalent than the estimates for other developmental conditions, such as autism. When we included pupils with varying non-verbal IQs, the prevalence estimate increased 50 per cent (to 7.58 rather than 4.8 per cent, which only includes those with NVIQ scores in the normal range).

Out sample did not include children from special needs schools and all were from a relatively affluent area, so the real figures may actually be higher.

We also found that children with low-average IQ scores did not generally experience more severe language deficits, educational difficulties, or social, emotional and behavioural problems than those who scored in the average range.

What does this mean?

The children we identified as having language disorder had higher social, emotional and behavioural problems, and 88 per cent failed to achieve early curriculum targets.

But crucially, our second finding means the diagnostic process for language disorders is flawed, and IQ shouldn’t be used as a cut-off for speech-language therapy support.

What is the current diagnostic process?

Schools will notice that a child is struggling with language at school – he or she might not understand instructions in the same way as other children, and will likely have reading problems.

The school’s special educational needs coordinator will then refer the child to a speech and language therapist. Language disorder is diagnosed when language skills (vocabulary, grammar and story-telling skills) are not developing as expected. Often, clinicians are looking for a gap between verbal and non-verbal abilities.

Children just below the “normal” non-verbal IQ range will often not be considered to have a “specific” language disorder, so may not meet eligibility for speech and language therapy.

But they may not qualify for services for children with learning disabilities either, as their NVIQ is not impaired enough. In other words, there is a gap.

What’s the problem with this process?

It’s not an evidence-based decision!

NVIQ should not be the factor that determines whether or not you get speech and language therapy.

The fifth revision of the diagnostic and statistical manual of mental disorders (DSM-5) removed the need for “normal” NVIQ in language disorder diagnoses. However, a below-average score is still the most common criterion used to exclude children from access to specialist help.

This definition creates a group of children with considerable language needs who fall between diagnostic categories; it leaves children with both verbal and non-verbal difficulties at a double disadvantage, with limited specialist support.

Where does the change need to happen?

First, there needs to be recognition that the evidence does not support using non-verbal IQ as an exclusion criterion for language disorder.

Schools also need to understand that some of the problems they are seeing in behaviour, learning and literacy development may be due to an underlying oral language problem.

Specialist support should be available according to language needs. Good services will see speech and language therapy working together with schools, in partnership.