New insights challenge assumptions about pain perception in people with intellectual disabilities

A comprehensive review reveals that pain in individuals with intellectual disabilities is more complex and varied than previously thought, highlighting the need for inclusive and standardised assessment methods to improve clinical care.

Researchers reviewing experimental pain studies in people with intellectual disability have found that pain is more complex than the old assumption that these patients feel less of it. The review, published in the Journal of Pain Research, examined studies using controlled noxious stimuli and painful clinical procedures to look at how people with intellectual disability respond to pain across different ages, diagnoses and levels of impairment.

The authors found 37 eligible studies, covering infants through adults and including groups with cerebral palsy, Down syndrome, Rett syndrome, Prader-Willi syndrome, WAGR syndrome and other causes of intellectual disability. More than half of the studies used quantitative sensory testing, or QST, a method that applies standardised stimuli such as heat, pressure or touch and then measures the response. Others looked at pain during vaccination, venepuncture or surgery. The review found that these methods are generally workable, but they often need adjustments for communication and cognitive limitations.

A key finding was that people with severe to profound intellectual disability were badly under-represented. When they were included, researchers usually relied on behavioural observation rather than self-report. Common tools included facial coding systems, the FLACC scale and checklist-based measures designed for non-verbal patients. The review also found that pain responses can differ by severity and cause of disability: some groups showed stronger facial or bodily reactions, while others appeared more withdrawn or showed less expressive pain behaviour.

The study also highlighted the limits of proxy reporting. Parents, nurses and researchers sometimes agreed with self-report, but not always, and concordance could weaken as pain became more intense. Physiological measures such as heart rate, skin conductance and brain imaging were promising in some studies, particularly event-related potentials on EEG, but results were inconsistent and sample sizes were small. The authors said this means there is still no single reliable objective marker for pain in this population.

Overall, the review argues for better-designed, more inclusive research that combines behavioural, physiological and, when possible, self-reported measures. It also calls for standardised methods, clearer reporting of disability severity and greater involvement of people with intellectual disability, families and caregivers in study design. The broader message is straightforward: pain in this group should not be assumed to be muted, and recognising it properly remains a major clinical challenge.