Consuming common opioid-based painkillers may triple the risk of side effects including personality changes, confusion and sedation among people with dementia, a study has warned.

It is because people with dementia produce increased amounts of endorphins -- body's natural endogenous opioids -- which interacts with brain to reduce our perception of pain, explained researchers from Britain's University of Exeter. Previous studies have recognized that pain is often under-diagnosed and poorly managed in people with dementia, impacting the quality of life. While the opioid-based painkillers ease pain effectively, current prescribing guidance does not consider the fact that people with dementia get effective pain relief from smaller doses than are commonly prescribed, and are particularly sensitive to adverse effects.

"Pain is a symptom that can cause huge distress and it's important that we can provide relief to people with dementia. Sadly at the moment we're harming people when we're trying to ease their pain," said Clive Ballard from the varsity. For the study, presented at the Alzheimer's Association International Conference 2018 in Chicago, the team analysed data from 162 people who had advanced dementia and significant depression.

The analysis showed buprenorphine -- opioid used to treat acute and chronic pain -- tripled the harmful effects on people who received the medication as part of their treatment. These patients were also found to be significantly less active during the day. The experiment done on mice model showed increased sensitivity to the opioid-based painkiller morphine upon treating arthritis in mice with Alzheimer's disease.

The mice with Alzheimer's responded to a much lower dose to ease pain, and experienced more adverse effects when the dose was increased to a normal level. "We urgently need more research in this area, and we must get this dosing right. We need to establish the best treatment pathway and examine appropriate dosing for people with dementia," Ballard explained.