Hospital-bound dementia patients are “suffering in silence” because they are unable to communicate the pain they are in, according to a new study.

Research by Marie Curie and University College London found that over a third of patients with the disease are unable to explain how they are feeling to hospital staff.

The researchers warned that both pain and delirium, a state of acute confusion to which old people are particularly susceptible, are common among dementia patients on hospital wards but these conditions are "often under-diagnosed and under-treated".

Roughly 40 per cent of all patients in acute hospital wards are thought to be suffering from dementia.

The team set out to examine the dementia severity, delirium and pain levels among 230 dementia patients aged 70 and over admitted to two British hospitals.

They found that almost half - 49 per cent - of the patients studied were suffering pain while resting, and delirium developed in 15 per cent.

Of the 35 per cent of participants who were delirious and unable to self-report pain, 33 per cent of these participants experienced pain at rest, according to the study, published in the journal Age And Ageing.

Meanwhile the odds of being delirious were 3.26 times higher in participants experiencing pain at rest.