Why do so many families with disabled children never receive a diagnosis?
The most obvious reason is that our knowledge remains limited. Even today, in 30 to 50 percent of people with intellectual disability, we cannot identify the cause—even in adulthood.
Diagnosing intellectual disability in young children is genuinely difficult. In my view, medical schools don't teach enough about developmental stages between birth and three years, how much variation from the norm is typical, and what constitutes actual pathology.
Parents' concerns are often dismissed. I've met families whose child wasn't speaking well or wasn't walking, and they were told not to worry—that patience was needed because not all children develop at the same pace.
So it often takes school entry for teachers to notice the delay and recommend a specialist evaluation.
For us doctors, telling parents their child has an intellectual disability is always grave. It changes their family's life. That's why we must always listen carefully—mothers often have precise observations to share—and watch closely whenever there's any doubt.
What obstacles do you encounter in pursuing a diagnosis?
First, we need to distinguish between diagnostic and etiological diagnosis. A diagnostic tells us whether there is delay or deficiency; an etiological diagnosis explains why. I tell families there are several aspects to consider: whether there is truly a delay, what can be done, and what might be causing it.
The real difficulty comes at the start. Where do you look? When and where do you stop? Some tests—even a simple blood draw—aren't easy on small children.
And some genetic analyses require substantial samples. To do an MRI on a young child, you need general anesthesia.
Is general anesthesia really necessary when an MRI doesn't always yield answers? Wouldn't it be better to wait until the child is six or seven?
Some children show clear clinical signs that guide our investigation and often lead us to find the cause. Many others present fairly even delays across all areas, yet have fairly normal clinical tests. Those require extensive investigation. But the milder the disability, the harder the diagnosis to find. We follow children whose disability origin remains unknown until adulthood. Those already diagnosed are followed less closely, and families can exhaust themselves waiting for answers that never come.
Is it absolutely necessary to know what caused the disability?
For most intellectual disabilities, we don't have "treatments" to cure the child, but we do have ways to support development. These approaches work whether or not we know the cause.
Knowing the cause helps us tailor rehabilitation, prevent complications, or monitor disease progression when we understand the natural history. Still, I find families feel easier with themselves over time once they have a diagnosis. They understand their child's difficulties better and can explain them.
And the advances in pediatric neurology and genetics are encouraging. We're running more therapeutic trials. It's worth pursuing a diagnosis. I think knowing the origin of a disability helps you live with it.
Florence Chatel, 2013
