The prevalence and nature of intellectual disability in Norwegian prisons.

Researchers visited every Norwegian prison and gave two quick tests.

They used the HASI screen first, then the WASI IQ test to double-check.

The goal was to learn how many inmates have intellectual disability.

One in ten prisoners scored below 70 IQ.

HASI results matched WASI results, so the screen works.

Most of these men had never been diagnosed before.

To et al. (2015) later showed the same HASI works in Dutch adults with drug problems.

Their study extends this one: if the tool is valid across languages and drugs, you can trust it in most clinics.

Keulen-de Vos et al. (2022) found that Dutch forensic patients with ID are younger and more often violent.

That picture fits the Norwegian numbers: prisons hold many undetected people with ID who also show risky behavior.

Laugeson et al. (2014) showed only two in a hundred medical trials include people with ID.

Together these papers paint the same gap: people with ID are hidden in prisons, hospitals, and research.

If you work in justice or forensic mental health, give the five-minute HASI to every new client.

A low score tells you to slow down, use plain language, and ask for disability services.

You will spot needs early, prevent behavior escalation, and link people to support that courts rarely offer.