#345 ‒ Chronic pain: pathways, treatment, and the path to physical and psychological recovery | Sean Mackey, M.D., Ph.D.

Episode Summary

Executive Summary: This episode is a deep dive into pain as a biopsychosocial phenomenon—how it is detected, transmitted, modulated, and treated. Peter Attia and Dr. Sean Mackey discuss pain’s evolutionary role, pain pathways and categories, brain-based modulation, chronic pain vulnerabilities, and practical management options ranging from NSAIDs and gabapentinoids to opioids, acupuncture, cannabis, and low-dose naltrexone. The conversation also includes Attia’s personal pain journey and recovery.

Main Topics: What pain is and why it exists (Priority: 5/5): Mackey defines pain as an unpleasant sensory and emotional experience linked to actual or potential tissue damage, emphasizing its evolutionary role as a survival signal and motivator rather than simply a symptom. From Cartesian dualism to biopsychosocial pain (Priority: 5/5): The discussion critiques the old body-mind split in pain science and argues that pain reflects integrated biological, psychological, and social inputs, not just tissue damage. Pain pathways, fibers, and categories (Priority: 5/5): They explain nociceptors, A-delta, C, and A-beta fibers, plus nociceptive, visceral, neuropathic, and nociplastic pain, showing how different mechanisms produce different experiences and treatment responses. Brain modulation, gate control, and variability (Priority: 5/5): Pain is shown to be heavily shaped by spinal gating and descending brain control from regions like the prefrontal cortex, insula, cingulate, amygdala, and thalamus; the same stimulus can feel very different across people and even within the same person over time. Chronic pain risk factors and functional rehabilitation (Priority: 5/5): Mackey highlights depression, anxiety, catastrophizing, sleep disruption, diabetes control, trauma history, and deconditioning as drivers of persistent pain, while stressing that restoring function is the real treatment goal. Medication and interventional treatment tradeoffs (Priority: 4/5): The episode reviews NSAIDs, acetaminophen, baclofen, gabapentin/pregabalin, antidepressants, opioids, TENS, acupuncture, and low-dose naltrexone, emphasizing individualized trial-and-error and balancing benefit against risk. Personal experience and empathy in pain medicine (Priority: 4/5): Attia recounts his severe disc-related injury, multiple surgeries, opioid exposure, and eventual recovery, using it to underscore how pain reshapes identity, sleep, emotion, and physician empathy.

Key Arguments: Pain is not just tissue damage; it is a sensory-emotional experience shaped by the brain, expectations, prior experiences, sleep, mood, and social context. Nociception and pain are distinct: injury signals can be present without conscious pain, and conscious pain requires an awake brain. Different pain types require different approaches; nociceptive pain often responds to NSAIDs/acetaminophen, while neuropathic pain often needs gabapentinoids, certain antidepressants, or other anti-neuropathic agents. The spinal cord and brain implement gating and descending inhibition, so touch, rubbing, heat/cold, and cognitive state can materially alter pain perception. Chronic pain is often maintained by central sensitization, fear-avoidance, catastrophizing, insomnia, and reduced self-efficacy, not just ongoing tissue injury. Pain treatment is inherently probabilistic and individualized; there is rarely one correct drug or procedure, and functional rehabilitation matters more than eliminating all sensation. Opioids are a tool, not a moral category; they can be lifesaving in selected settings but have major societal and individual risks when overused or poorly targeted. Low-dose naltrexone may help some chronic pain and neuroinflammatory conditions, but mechanisms and ideal candidates remain uncertain. Objective biomarkers of pain are improving via fMRI and machine learning, but self-report remains the clinical gold standard for current pain. Patients do best when pain is addressed early, holistically, and with clear expectations about recovery, setbacks, and rehabilitation.

Data Points: Formal definition of pain: “an unpleasant sensory and emotional experience associated with actual or potential tissue damage” - Mackey’s opening definition of pain C fiber conduction speed: ~1 meter/second - Slow, burning, longer-latency pain transmission A-delta fiber conduction speed: ~10 meters/second - Fast, sharp, well-localized pain transmission A-beta fiber conduction speed: ~100 meters/second - Touch/proprioceptive fibers that can gate pain Pain signal timing from thumb to brain via C fiber: ~1–2 seconds - Illustration of slow pain transmission Fibromyalgia gender distribution (historical): ~80% women - Mackey notes older criteria skewed female, though newer criteria identify more men Chronic pain prevalence in the U.S.: 50–100 million people - Estimated population burden depending on case definition High-impact chronic pain prevalence: ~8% of the population - People with substantial activity limitations due to pain Low back pain prevalence among chronic pain conditions: ~28% - Most common chronic pain category mentioned Neck pain prevalence among chronic pain conditions: ~16% - Common chronic pain category Headache prevalence among chronic pain conditions: ~16% - Common chronic pain category Societal cost of chronic pain: Over $0.5 trillion/year - Estimated economic burden in the U.S. Experimental heat stimulus in pain study: 48°C - Used to demonstrate wide variation in pain ratings across people Attia’s acute opioid exposure during severe pain: ~320 mg OxyContin/day - Personal story during his worst pain period Gabapentin dose discussed: Up to 4 grams/day - Used for severe neuropathic pain but causes drowsiness Pregabalin transport profile: Linear kinetics - Allows more predictable dose-response than gabapentin Typical acetaminophen daily ceiling (historical): Up to 4 grams/day - Mackey notes more conservative modern guidance toward 2 grams/day for some patients Ibuprofen regimen example: 400 mg three times daily - Attia’s own successful OTC pain stack with acetaminophen Naproxen regimen example: 500 mg twice daily - Mackey’s personal effective NSAID dose Low-dose naltrexone dose: 4.5 mg - Used off-label for chronic pain/neuroinflammation; derived from weight-based conversion Naltrexone addiction dose: 50 mg - Standard opioid/alcohol-use treatment dose Tacit proportion with fibromyalgia and pain modulation impairment: Conditioned pain modulation impaired, especially in women with fibromyalgia - Described as reduced endogenous inhibitory control Stanford pain department size at time of first meeting: 10–12 people - Early small pain program Stanford pain department size today: ~130–150 people - Growth into a major academic pain center

Pivotal Quotes: "Pain is one of the most primitive experiences... It's either pain or reward. You're either being driven towards oxygen, food, sex, or you're trying to get away from danger." — Dr. Sean Mackey: Explaining pain’s evolutionary role as a survival mechanism "The amount of stimulus or nociception may have little to nothing to do with your experience of pain." — Dr. Sean Mackey: Core lesson on why identical injuries can feel radically different "I am not pro-opioid. I am not anti-opioid. I am pro-patient." — Dr. Sean Mackey: His framework for responsible opioid use and individualized care

Implications: Listeners should rethink pain as a brain-body state, not just a tissue problem. For medicine, the future is multimodal, personalized, and function-centered, with better biomarker tools, smarter opioid stewardship, and stronger integration of sleep, rehab, and psychology.