Chronic pain is associated with numerous physical and mental health issues, leading to a significant impact on healthcare expenses and a decline in work productivity. The prevalence of chronic pain in the United States is one of the highest among chronic health conditions, though precise estimates differ.
A 2019 National Health Interview Survey, which included a module on persistent pain, revealed that 50.2 million adults, or 20.5% of the population, reported experiencing pain on a majority of days or daily.
These results suggest that over one in five American adults suffer from persistent pain, highlighting the need for greater focus on managing the impact of this debilitating condition.
The origins of chronic pain can vary. It may be caused by an enduring illness, such as arthritis or cancer, which results in continuous discomfort. Additionally, injuries and diseases can induce alterations in the body that increase pain sensitivity.
According to a new study published in the British Journal of Pharmacology, alcohol intake and alcohol withdrawal can also lead to unrelieved chronic pain.
In this groundbreaking research, a group of scientists from Scripps demonstrated how both alcohol intake and withdrawal can contribute to heightened pain and sensitivity.
Persistent alcohol use could increase pain sensitivity via two distinct molecular pathways — one influenced by alcohol consumption and the other by withdrawal. This is a key finding by researchers at Scripps Research, who have been investigating the intricate relationship between alcohol and pain.
The study also proposes possible novel therapeutic targets for addressing chronic pain and heightened sensitivity associated with alcohol consumption.
Alcohol use disorder (AUD) covers a range of conditions typically referred to as alcohol abuse, alcohol dependence, and alcohol addiction. As per the 2021 National Survey on Drug Use and Health, 29.5 million individuals in the U.S. are affected by AUD. Prolonged AUD can lead to the development of several chronic illnesses, including heart disease, stroke, liver disease, and certain cancers.
One of the numerous consequences of long-term alcohol consumption is pain, with over half of those with AUD experiencing some form of persistent discomfort. This includes alcoholic neuropathy, a type of nerve damage resulting in chronic pain and other symptoms. Research has also identified a connection between AUD and alterations in the brain’s pain signal processing, as well as changes in immune system activation. Consequently, this pain can contribute to increased alcohol intake. Furthermore, during withdrawal, individuals with AUD may encounter allodynia, a condition where a typically harmless stimulus is perceived as painful.
Senior author Marisa Roberto and her team aimed to investigate the root causes of various alcohol-related pain types. In their recent study, they analyzed three groups of adult mice: those dependent on alcohol (heavy drinkers), those with limited access to alcohol and considered non-dependent (moderate drinkers), and those never exposed to alcohol.
The dependent mice experienced allodynia during alcohol withdrawal, but their pain sensitivity significantly decreased with subsequent alcohol access. Conversely, around half of the non-dependent mice also displayed heightened pain sensitivity during alcohol withdrawal. However, unlike the dependent mice, their neuropathy did not subside upon re-exposure to alcohol.
After measuring inflammatory protein levels in the animals, Roberto’s team found that inflammation pathways were elevated in both dependent and non-dependent mice. However, specific molecules were only increased in the dependent mice. This suggests that distinct molecular mechanisms could be responsible for the two pain types and identifies potential inflammatory proteins as drug targets to address alcohol-related pain.
According to the study’s lead author, Vittoria Borgonetti, PhD, a postdoctoral associate at Scripps Research, the two pain types differ significantly, emphasizing the importance of distinguishing between them and developing tailored treatment approaches for each type.
The team led by Roberto is persisting in their research to explore how these molecules could be employed for diagnosing or treating chronic pain conditions related to alcohol consumption.
“Our goal is,” adds co-senior author Nicoletta Galeotti, “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.”
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