Unraveling the Psychological Mechanisms Behind Smoking in Chronic Pain
The link between smoking and chronic pain is complex and multidirectional. To gain a perspective on how current knowledge on this relationship can be applied in clinical practice to help patients stop smoking, Practical Pain Management talked with Joseph W. Ditre, PhD, Assistant Professor of Psychology at Syracuse University, in Syracuse, NY. Dr. Ditre is a leading researcher in health psychology, with a focus on the intersection of addictive behaviors and comorbid medical disorders.
Q: How are smoking and chronic pain related?
A: We think of relationships between pain and smoking as being reciprocal in nature. Smoking has been purported to hasten the onset and increase the intensity of pain, and pain has been shown to motivate smoking behavior. This sort of vicious cycle could result in greater pain and make quitting smoking more difficult (Figure 1).1,2
Four mechanisms that may help to explain relations between pain and smoking include:
• Nicotinic acetylcholine receptors (nAChRs) and acute analgesic effects of nicotine/tobacco—nAChRs are spread widely throughout the central and peripheral nervous systems, and self-administered nicotine has been shown to result in the activation of spinal cord descending pain inhibitory pathways. For patients in pain, acute analgesic effects of nicotine could make smoking more rewarding and harder to give up.
• Endogenous opioid system—Pain-related effects of nicotine and other nAChR agonists may be mediated at least partially by the activation of endogenous opioid (endorphin) systems. For example, with regard to acute analgesic effects of nicotine, there is evidence that smoking can stimulate the release of b-endorphins, which have been referred to as the body’s natural painkillers. However, as described in a 2010 review by Shi et al, there also is evidence that chronic exposure to nicotine might result in the dysregulation of endogenous systems that influence a multitude of pain-relevant processes (eg, increased hyperalgesia, impaired baroreceptor function, and decreased b-endorphin levels).3
• Cardiovascular responses—Smoking also may produce acute analgesic effects via pressor actions on the cardiovascular system that serve to alter peripheral blood flow. For example, nicotine has been shown to elevate blood pressure in both smokers and nonsmokers, and this increased cardiovascular reactivity has been associated with reduced pain responses.4
• Expected smoking-related outcomes—Expectations or beliefs about how smoking may help one cope with or reduce pain could be just as important as some of the more biological mechanisms, especially when it comes to helping people quit. Whether they are explicitly aware of it or not, patients may be motivated to continue smoking, in part, due to the pain they are experiencing and their desire to reduce it or distract themselves from it. This refers to the patient’s perception of how smoking might help them manage or deal with pain, versus how nicotine may actually influence pain pathways.
Q: How can pain practitioners assess the psychological mechanisms behind smoking behaviors in their patients?
A: This to me is central when it comes to helping persons in pain quit smoking, and we have developed a measure to examine that. The 9-item Pain and Smoking Inventory is designed to assess 3 domains: 1) the extent to which pain motivates patients’ smoking behavior, 2) the extent to which patients believe that smoking helps them cope with pain, and 3) the extent to which patients see pain as a potential barrier to quitting smoking.5
An example item is: ‘My pain makes me less confident that I could stop smoking for good.’ Patients rate that question on a scale from 0 to 6, with 0 being not at all true and 6 being extremely true. The initial validation manuscript for this measure is in preparation.
Even if not assessed with this measure, clinicians should consider asking patients about how smoking may be related to their pain, and vice versa. This approach could provide an opening to further discuss some of the emerging research on pain and smoking (eg, ‘you might be surprised to learn that smoking has been associated with increased pain and that quitting smoking may help to improve your pain and functioning’). If taken to heart, this information could cause patients to look at their smoking behavior in a different light than maybe they had seen it before.
For example, many people are aware of the widespread harmful effects of tobacco smoking, but for patients who are seeking treatment for pain, there may be no better motivator to quit than coming to understand that continued smoking may interfere with their goals for reduced pain and better physical functioning. For smokers with chronic pain, tobacco smoking might be seen as one of the few things they can still enjoy, but what they might not know is that continued smoking could be perpetuating the exact thing they would like to rid themselves of most.
Michael Hooten, MD, and colleagues recently published a study demonstrating that pain patients seeking treatment readily report that they smoke tobacco to cope with, or distract themselves from, their pain.6 This makes a great deal of sense, especially given that smokers, in general, tend to smoke in response to a variety of aversive sensory, affective, and cognitive states. Whether smoking actually results in pain reduction or mood enhancement may be less important than whether patients’ expectations that smoking will reduce pain are sufficient to motivate them to keep smoking. In this way, expectations for how pain and smoking are interrelated could be of primary import in the context of smoking cessation.
Q: How can health care providers help patients with pain conditions quit smoking?
A: The current gold-standard treatment for tobacco cessation includes a combination of pharmacotherapy, such as nicotine replacement therapy or varenicline (Chantix), and behavioral or skills-based counseling interventions. Although each of these strategies has been shown to enhance smoking cessation, a combination tends to work better than any approach alone.