Scientists have unraveled the biological mechanisms by which alcohol addiction can make people more sensitive to pain.
The research, published recently in the British Journal of Pharmacology, may lead to the development of new drugs for treating alcohol abuse-related chronic pain and hypersensitivity.
“Pain is both a widespread symptom in patients suffering from alcohol dependence, as well as a reason why people are driven to drink again,” senior author Marisa Roberto from the Scripps Research Institute said in a statement.
Alcohol use disorder (AUD) includes conditions commonly called alcohol abuse, alcohol dependence and alcohol addiction, which affects nearly 30 million people in the US.
Previous research has shown AUD can trigger the development of numerous chronic diseases like heart disease, stroke, liver disease and some cancers.
Long-term alcohol consumption has also been related to pain with over half of people with AUD reporting that they experience persistent pain of some type.
Some of the reported symptoms linked to AUD include alcoholic neuropathy – a severe form of nerve damage that causes chronic pain and other symptoms.
This pain is in turn also associated with further alcohol consumption, scientists said.
Research has also shown that AUD is linked to changes in how the brain processes pain signals, as well as changes in how the immune system gets activated.
In some people experiencing alcohol withdrawal effects, AUD may lead to a condition called allodynia in which harmless stimuli are perceived as painful.
In the new study, scientists assessed the underlying causes of these different types of alcohol-related pain.
They compared three groups of adult mice – rodents that were excessive drinkers, those that had limited access to alcohol and were moderate drinkers and mice that had never been given alcohol.
Researchers found the alcohol-dependent mice developed allodynia during withdrawal, but subsequent alcohol access significantly decreased their pain sensitivity.
About half of the mice that were not dependent on alcohol also showed signs of increased pain sensitivity during alcohol withdrawal.
However, unlike the dependent mice, this was not reversed by re-exposure to alcohol.
Researchers then measured levels of inflammation-related proteins in the animals.
They found that while these molecules were elevated in both dependent and non-dependent animals, specific ones were only increased in dependent mice.
Based on this observation, they suggested that different biological mechanisms may drive the two types of pain.
“These two types of pain vary greatly, which is why it is important to be able to distinguish between them and develop different ways to treat each type,” study co-author Vittoria Borgonetti said.
The new findings also point to the types of proteins that may be useful as drug targets to combat alcohol-related pain.
Scientists are continuing to see how these molecules might be used to diagnose or treat alcohol-related chronic pain conditions.
“Our goal is to unveil new potential molecular targets that can be used to distinguish these types of pain and potentially be used in the future for the development of therapies,” said Nicoletta Galeotti, another author of the study.
