Summary: A new study shows that abstinent smokers experience increased pain sensitivity related to altered activity in specific brain regions. Compared with nonsmokers, abstinent smokers required more postoperative pain relief (especially opioids) and their pain sensitivity increased the longer they remained nicotine-free.
These effects appeared within a defined withdrawal window, aligning with evidence that pain responses normalize after approximately three months. Understanding these neural mechanisms may help refine preoperative guidelines and reduce opioid dependence in smokers preparing for surgery.
Key facts
Greater sensitivity to pain: Abstinent smokers showed greater responses to pain and required more postoperative analgesics. Change in brain activity: Different neural networks were associated with pain sensitivity and withdrawal-related attention needs. Time-dependent effect: Pain sensitivity increased with abstinence, but may normalize after three months.
Source: SfN
Abstinent smokers experience increased pain sensitivity during withdrawal, to the point that they often need more pain relief after surgery. Because?
New to the Journal of Neuroscience, Zhijie Lu of Fudan University Minhang Hospital and Kai Wei of Shanghai Oriental Hepatobiliary Surgery Hospital led a team of researchers to explore the brain activity linking nicotine withdrawal and pain sensitivity.
The researchers found that 30 abstinent smokers had altered functioning of specific brain areas, increased sensitivity to pain, and a need for greater postoperative pain relief, particularly with opioids, compared to 30 non-smokers.
The longer smokers abstained from smoking, the more sensitive they were to pain, which was associated with a different set of brain regions.
Notably, this effect was limited to a specific time period of abstinence, supporting previous findings that pain sensitivity can return to normal levels once abstinence exceeds 3 months.
The relationship between postoperative care requirements and withdrawal symptoms was linked to a different set of brain regions.
Wei says: “We would like to emphasize that our study does not discourage smokers from quitting before surgery.
“Our goal is to encourage researchers to delve deeper into the mechanisms underlying elevated pain sensitivity during short-term withdrawal, with the goal of developing strategies to mitigate the clinical challenge of increased analgesic use (especially opioids) associated with preoperative smoking cessation.”
Researchers have already begun to explore the mechanisms of a postoperative analgesic that may be more effective than opioids in abstinent smokers, as well as the mechanisms and effectiveness of preoperative nicotine replacement therapies.
Key questions answered:
A: Altered activity in specific brain regions during nicotine withdrawal increases pain processing and increases sensitivity.
A: No: The findings emphasize understanding and managing withdrawal-related pain, not discouraging quitting.
A: The effect has a limited duration and may return to normal after approximately three months of abstinence.
Editorial notes:
This article was edited by a Neuroscience News editor. Magazine article reviewed in its entirety. Additional context added by our staff.
About this research news on pain and neuroscience
Author: SfN Media
Source: SfN
Contact: SfN Media – SfN
Image: Image is credited to Neuroscience News.
Original Research: Closed access.
“Altered regional brain activity underlying increased postoperative analgesic requirements in abstinent smokers: a prospective cohort study” by Zhijie Lu et al. Neuroscience Magazine
Abstract
Altered Regional Brain Activity Underlying Increased Postoperative Analgesic Requirements in Abstinent Smokers: A Prospective Cohort Study
Perioperative abstinent smokers experience increased pain sensitivity and increased postoperative analgesic needs, likely due to nicotine withdrawal-induced hyperalgesia.
However, the underlying neural mechanisms in humans remain unclear.
To address this issue, this study recruited 60 male patients (30 abstinent smokers and 30 non-smokers) undergoing partial hepatectomy, collecting clinical data, smoking history, pain-related measures, and resting-state functional magnetic resonance imaging (rs-fMRI).
Compared with non-smokers, abstinent smokers showed a lower pain threshold and higher postoperative analgesic needs.
Neuroimaging revealed altered brain function in abstinent smokers, including reduced fractional amplitude of low-frequency fluctuations (fALFF, 0.01 – 0.1 Hz) in the ventromedial prefrontal cortex (vmPFC), increased regional homogeneity (ReHo) in the left middle occipital gyrus, and decreased functional connectivity (FC) between the vmPFC with the bilateral middle temporal gyrus and the precuneus.
Preoperative pain threshold was positively correlated with abstinence duration and specific regional brain activities and connectivity. Furthermore, the observed association between abstinence time and pain threshold was mediated by the activity of the calcarine and posterior cingulate cortex.
Dysfunction in vmPFC and left anterior cingulate cortex was fully mediated by the association between withdrawal symptoms and postoperative analgesic requirements.
These findings suggest that nicotine withdrawal could alter functional brain activity and contribute to hyperalgesia in abstinent smokers.
This study provided novel insights into the supraspinal neurobiological mechanisms underlying nicotine withdrawal-induced hyperalgesia and potential therapeutic targets for postoperative pain in abstinent smokers.
