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The Musculoskeletal Wrangler, Wonthaggi (2026)

12/04/2026

Chronic pain and memory
BACKGROUND:
🔎Working memory is a core executive function responsible for temporarily holding and manipulating information to support complex cognitive tasks. Individuals with chronic pain often report “brain fog” or cognitive difficulties, but evidence across studies has been inconsistent.
📍A meta-analysis by Berryman et al. (2013) synthesised evidence from 27 observational studies comparing working memory performance in adults with chronic pain versus pain-free controls. Tasks typically included n-back paradigms, digit span, and other standard working memory measures.
FINDINGS:
🧠 Individuals with chronic pain showed small but significant working memory deficits compared with controls.
✅Deficits were more consistent in more demanding working memory tasks (higher cognitive load conditions).
📈Evidence suggested a dose–response relationship, where greater pain severity was associated with poorer working memory performance.
⚠️Psychological factors (e.g., depression, anxiety) partially contributed but did not fully explain the impairments.
IMPLICATIONS:
📚Chronic pain is associated with measurable but subtle deficits that may affect attention, decision-making, learning, and self-management of pain conditions. Thus, chronic pain involves distributed cognitive and neural resource disruption, not just sensory processing.
SUMMARY:
📖Chronic pain is associated with small but reliable working memory impairments, particularly under higher cognitive demands. While not uniform across all studies, the overall evidence supports working memory disruption as part of the broader cognitive impact of chronic pain.
MW
Reference:
Berryman C, Stanton TR, Bowering KJ, Tabor A, McFarlane A, Moseley GL. Evidence for working memory deficits in chronic pain: A systematic review and meta-analysis. Pain. 2013;153(6):1184–1196.

12/04/2026

Chronic pain and executive function
BACKGROUND:
🔎Chronic pain is increasingly understood as a condition that affects not only sensory and emotional processing but also cognitive function. Executive functions, such as inhibition, working memory, and cognitive flexibility, are essential for goal-directed behaviour and may be disrupted in individuals with persistent pain.
📍A meta-analysis by Berryman et al. (2014) collated the data of 25 studies to examine the executive function among individuals with chronic pain.
FINDINGS:
🧠 Individuals with chronic pain showed small to moderate impairments in executive function compared with controls.
📈Deficits were most consistently observed in attention, cognitive flexibility, and working memory updating.
⛔️Evidence for inhibitory control deficits was present but less consistent.
⚠️Cognitive differences were partially influenced by factors such as depression, anxiety, medication use, and pain intensity, though not fully explained by them.
⚠️Potential confounding from psychological distress, sleep disturbance, and medication effects.
IMPLICATIONS:
📚Findings support the view that chronic pain involves wider central nervous system and cognitive alterations, not solely sensory dysfunction.
📚Cognitive impairments may impact self-management, adherence to treatment, and daily functioning, suggesting value in incorporating cognitive considerations into pain rehabilitation.
SUMMARY:
📖Chronic pain is associated with subtle but reliable impairments in executive functioning, particularly in working memory and cognitive flexibility. However, heterogeneity and confounding variables limit definitive conclusions, highlighting the need for more standardised and longitudinal research.
MW
Reference:
Berryman C, Stanton TR, Bowering KJ, Tabor A, McFarlane A, Moseley GL. Do people with chronic pain have impaired executive function? A meta-analytical review. Pain. 2014;155(10):2183–2191.

12/04/2026

Pain perception
Part 2: biopsychosocial influences
BACKGROUND:
🔎While existing literature found inconsistent s*x differences in experimental pain without explaining their variability, it remains unclear whether biopsychosocial factors influence pain sensitivity differently in women and men. This represents a shift from purely biological explanations toward a more multifactorial understanding of pain.
📍A large two-part systematic review by Racine et al. (2012) synthesised findings from 172 experimental studies to examine whether biopsychosocial factors influence pain perception differently between males and females.
BIOLOGICAL:
⚠️Hormonal influences and endogenous pain modulation: inconsistent and inconclusive evidence
PSYCHOLOGICAL:
✅Pain catastrophising, anxiety, and fear of pain were associated with heightened pain responses; these factors were often more prevalent in women and appeared to contribute to increased pain sensitivity.
SOCIAL & CONTEXTUAL:
✅Pain responses are shaped by social and contextual influences. Gender norms and expectations, as well as characteristics of the experimental setting may bias reporting behaviours, with men more likely to underreport pain and women more likely to express it in certain contexts.
SUMMARY:
📖Biopsychosocial factors, particularly psychological and social influences appear to play a significant role in shaping pain responses, suggesting that apparent s*x differences in pain are contextual and mediated rather than inherent.
📚More quality research is required to further explore the role of biological factors on pain perception between male and females.
MW
Reference:
Racine M, Tousignant-Laflamme Y, Kloda LA, Dion D, Dupuis G, Choinière M. A systematic literature review of 10 years of research on s*x/gender and pain perception—Part 2: Do biopsychosocial factors alter pain sensitivity differently in women and men? Pain. 2012;153(3):619–635.

12/04/2026

Pain perception
Part 1: male vs. female differences
BACKGROUND:
🔎Epidemiological research suggests that women report more frequent, severe, and widespread pain than men. Historically however, women were underrepresented in research due to perceived biological complexity (e.g., hormonal cycles), limiting understanding of s*x differences in pain.
📍A large systematic review by Racine et al. (2012) collated the data of 172 studies to investigate any male and female differences in pain perception across 10 years of experimental pain research.
DEFINITIONS:
📝Pain threshold: the minimum intensity at which a stimulus is first perceived as painful
📝Pain tolerance: the maximum intensity or duration of pain a participant is willing to endure.
📝Pain unpleasantness: affective/emotional dimension of pain, often rated separately from intensity.
MALE vs. FEMALE FINDINGS:
📉Pain tolerance: significantly lower in women across the review
📉Pressure pain threshold: frequently lower in women
⛔️Thermal, cold and ischemic pain thresholds: no significant differences
⛔️Pain intensity & unpleasantness: no significant differences
SUMMARY:
📖Despite widespread assumptions, 10 years of experimental research show no consistent or robust s*x differences in pain perception, with only modest, modality-specific variations (e.g., lower tolerance in women), suggesting that pain differences are complex and not solely biologically determined.
MW
Reference:
Racine M, Tousignant-Laflamme Y, Kloda LA, Dion D, Dupuis G, Choinière M. A systematic literature review of 10 years of research on s*x/gender and experimental pain perception—Part 1: Are there really differences between women and men? Pain. 2012;153(3):602–618.

12/04/2026

Pain education:
Reconceptualising change
BACKGROUND:
🔎Traditional models of learning often assume that knowledge change occurs through simple accumulation or replacement of incorrect ideas. However, Dole and Sinatra argue that meaningful conceptual change is more complex, involving active cognitive construction influenced by both prior knowledge and motivational factors.
📍A conceptual review by Dole & Sinatra (1998) propose that knowledge change should be understood as a dynamic process in which individuals evaluate, integrate, and sometimes restructure existing beliefs in response to new information. Rather than being purely rational or linear, conceptual change depends on the interaction between cognitive engagement and the perceived plausibility of new ideas.
MODELS OF ATTITUDE & BELIEFS CHANGE:
📝Belief change can occur through either low-effort, peripheral processing, where individuals make superficial adjustments based on cues such as credibility or familiarity, or high-effort, central processing, where individuals critically evaluate and deeply integrate new information.
🕵️‍♂️The likelihood of engaging in either pathway depends on motivation, prior knowledge, and the perceived relevance and plausibility of the message.
FACTORS AFFECTING MOTIVATION (pictured):
📚Motivation plays a key role in determining whether individuals engage in superficial or deep processing. Optimal conceptual change occurs when information is sufficiently discrepant to prompt reconsideration, yet remains:
🔅Comprehensible
🔅Plausible
🔅Coherent
🔅Compelling
SUMMARY:
📖Pain education can be understood as a process of conceptual change rather than simple information delivery, requiring not only accurate content but also sufficient motivation, trust, and cognitive engagement for patients to move from superficial belief adjustment to deeper restructuring of pain-related understanding.
MW
Reference:
Dole JA, Sinatra GM. Reconceptualizing change in the cognitive construction of knowledge. Educ Psychol Rev. 1998;10(2):109–136.

12/04/2026

Beyond nociception:
Imprecision hypothesis
(BACKGROUND) ASSOCIATIVE LEARNING OF PAIN:
🔎A key mechanism contributing to chronic pain development is associative learning, where neutral or non-threatening stimuli become linked with pain through repeated co-occurrence with noxious experiences. Over time, contextual cues, movements, environments, or bodily sensations can acquire predictive value for pain, even when actual nociceptive input is minimal. This learned association can amplify perceived threat and interact with imprecise coding, further reinforcing pain persistence.
📍A topical review by Moseley & Vlaeyen (2015) discuss the imprecision hypothesis that proposes chronic pain arises from uncertainty or “imprecision” in the brain’s interpretation of sensory signals. Rather than being a simple amplification of nociception, chronic pain reflects a predictive processing problem in which the brain assigns excessive weight to uncertain or noisy sensory inputs.
PRECISE CODING:
🔆With precise coding, sensory signals are assigned appropriate reliability, allowing the brain to accurately integrate nociceptive input with prior expectations. In this state, pain is more likely to reflect actual tissue status and functional relevance, meaning clinical management can more confidently focus on peripheral drivers such as injury, inflammation, or biomechanics.
IMPRECISE CODING:
🔆In contrast, imprecise coding shifts pain away from being a reliable marker of tissue state toward a problem of sensory inference. Here, ambiguous or noisy inputs are over-weighted, increasing the influence of expectation, attention, and prior learning. Clinically, this means pain persistence may be maintained even after tissue recovery, and traditional peripheral-focused treatments may show limited effectiveness.
SUMMARY:
📖While precise coding aligns pain more closely with peripheral pathology and biomechanical correction, imprecise coding reframes pain as a centrally maintained perceptual state driven by uncertainty, requiring strategies that target prediction, learning, and interpretation as much as tissue-level factors.
MW
Reference:
Moseley GL & Vlaeyen JWS. Beyond nociception: the imprecision hypothesis of chronic pain. Pain,2015;156(1):35-38.

12/04/2026

The inflammatory reflex:
Part 4: “set point” of the immune system
BACKGROUND:
🔎The “set point” concept refers to the idea that the brain continuously monitors immune activity and regulates it toward an optimal level of inflammatory tone. Rather than allowing inflammation to escalate unchecked or remain fully suppressed, the nervous system, particularly via the vagus nerve, acts to maintain a balanced physiological baseline.
📍An updated paper by Tracey (2009) describes the “reflex control of immunity” as a structured, bidirectional communication system in which the central nervous system monitors and modulates immune activity. Similar to other physiological reflexes, sensory inputs signal immune status to the brain, which then generates coordinated efferent responses to maintain homeostasis. This framework reframes inflammation as a tightly regulated variable under neural control, analogous to other homeostatic systems (e.g., temperature or blood pressure regulation).
CONCEPT:
🔆The “set point” concept can be understood by considering situations where immune activity is driven away from its baseline and then actively corrected back toward equilibrium via vagal control.
PRO-INFLAMMATORY SHIFT:
📈An upward shift in the inflammatory set point typically occurs during acute infection or tissue injury. For example, in bacterial sepsis, immune cells become highly activated and large quantities of cytokines such as tumour necrosis factorare released. While adaptive in the short term for pathogen clearance, this response can overshoot, leading to a dysregulated systemic inflammatory state.
ANTI-INFLAMMATORY SHIFT:
📉A downward (immunosuppressed) shift may occur in chronic illness, ageing, or prolonged stress, where immune responsiveness becomes blunted. In these states, the system is less able to mount an adequate inflammatory response to infection or tissue damage. Although less explicitly developed in early inflammatory reflex literature, the same regulatory framework suggests that reduced afferent signalling and altered vagal tone may contribute to insufficient efferent immune activation, leaving the organism below its optimal inflammatory set point and increasing vulnerability to infection and impaired healing.
SUMMARY:
📖When immune activity deviates from its set point, afferent signalling via the vagus nerve conveys this change to central autonomic circuits. In response, efferent output engages mechanisms such as the cholinergic anti-inflammatory pathwayto modulate cytokine release, including mediators like tumour necrosis factor, thereby restoring physiological equilibrium.
MW
Reference:
Tracey KJ. Reflex control of immunity. Nat Rev Immunol. 2009;9(6):418–428.

12/04/2026

The inflammatory reflex:
Part 3: functional anatomy
BACKGROUND:
🔎Immune function is not autonomous, but is instead integrated with neural control systems. This challenges the traditional separation of the nervous and immune systems and introduces the concept that immunity can be regulated through reflex pathways.
📍An updated commentary by Tracey (2009) describes the “reflex control of immunity” as a structured, bidirectional communication system in which the central nervous system monitors and modulates immune activity. Similar to other physiological reflexes, sensory inputs signal immune status to the brain, which then generates coordinated efferent responses to maintain homeostasis. The functional anatomy of the inflammatory reflex centres on a bidirectional neural circuit primarily mediated by the vagus nerve.
FUNCTIONAL ANATOMY:
🔆Afferent (sensory) fibres detect peripheral inflammatory signals—such as cytokines—and transmit this information to the brainstem, where it is integrated within autonomic control centres.
🔆Efferent (motor) output then travels via the vagus nerve to modulate immune activity in peripheral tissues. This occurs through the cholinergic anti-inflammatory pathway, in which acetylcholine is released and interacts with immune cells, particularly macrophages, to suppress pro-inflammatory cytokine production, including tumour necrosis factor.
SUMMARY:
📖The inflammatory reflex is a bidirectional neural circuit centred on the vagus nerve, where afferent signals detect peripheral inflammation and efferent outputs modulate immune activity. Through the cholinergic anti-inflammatory pathway, it suppresses pro-inflammatory cytokine release to maintain immune homeostasis.
MW
Reference:
Tracey KJ. Reflex control of immunity. Nat Rev Immunol. 2009;9(6):418–428.

12/04/2026

The inflammatory reflex:
Part 2: vagus nerve
BACKGROUND:
🔎The vagus nerve functions as both a sensor and regulator, forming a rapid, reflexive feedback loop that maintains immune homeostasis and prevents unchecked inflammatory responses.
📍A commentary paper by Tracey (2002) proposes the vagus nerve serves as the central communication pathway linking the nervous and immune systems through both sensory and motor functions. Hence, forming an inflammatory reflex; a bidirectional communication loop between the nervous and immune systems.
AFFERENT:
🔅The vagus nerve detects peripheral inflammation by sensing signals such as cytokines and other inflammatory mediators. These signals are transmitted to the brain, particularly to regions involved in autonomic regulation, allowing the central nervous system to monitor the body’s inflammatory state in real time.
EFFERENT:
🔅The vagus nerve actively modulates the immune response. Through what is termed the cholinergic anti-inflammatory pathway, vagal output leads to the release of acetylcholine, which interacts with receptors on immune cells such as macrophages. This interaction suppresses the production of pro-inflammatory cytokines, including tumour necrosis factor, thereby limiting excessive inflammation without broadly impairing immune function.
TREATMENT CONSIDERATIONS:
👩‍⚕️Unlike systemic anti-inflammatory drugs, which broadly suppress immune function, vagal stimulation can modulate immune responses in a more targeted and reflexive manner. This raises the potential for fewer side effects, particularly reduced risk of immunosuppression.
CHALLENGES:
⚠️Translating the inflammatory reflex into practice is limited by uncertainty around optimal parameters for vagus nerve stimulation and variability in patient response to targeting the vagus nerve.
⚠️Incomplete understanding of broader neuro-immune interactions, beyond the cholinergic anti-inflammatory pathway, also affects the predictability of outcomes.
⚠️Additionally, challenges related to cost, accessibility, and limited long-term safety data continue to constrain widespread clinical adoption.
MW
Reference:
Tracey KJ. The inflammatory reflex. Nature. 2002;420(6917):853–859.

12/04/2026

The inflammatory reflex:
Part 1: a novel concept
BACKGROUND:
🔎The “inflammatory reflex” challenges the traditional view that inflammation is regulated solely by the immune system. Instead, it proposes that the nervous system, in particular the vagus nerve, plays a central role in detecting and modulating inflammatory processes.
📍A commentary paper by Tracey (2002) proposes the inflammatory reflex is a bidirectional communication loop between the nervous and immune systems. Sensory (afferent) signals detect inflammatory stimuli and relay this information to the brain, which in turn sends motor (efferent) signals to regulate the immune response. This reflexive control allows for rapid, targeted modulation of inflammation.
MECHANISMS:
🔆A key component of this reflex is the cholinergic anti-inflammatory pathway. Through efferent vagal signalling, acetylcholine is released and binds to receptors on immune cells, particularly macrophages. This interaction inhibits the production of pro-inflammatory cytokines such as tumour necrosis factor, thereby attenuating the inflammatory response without broadly suppressing immune function.
IMPLICATIONS:
🔆Understanding the inflammatory reflex has important clinical implications. It supports the development of bioelectronic medicine approaches, such as vagus nerve stimulation, to treat inflammatory conditions. This offers a potential alternative or adjunct to pharmacological therapies, with the advantage of more targeted modulation of immune activity.
SUMMARY:
📖The inflammatory reflex reframes inflammation as a neuro-immune process under direct neural control. By identifying specific neural circuits that regulate immune responses, this work provides a foundation for innovative therapeutic strategies aimed at modulating inflammation through the nervous system.
MW
Reference:
Tracey KJ. The inflammatory reflex. Nature. 2002;420(6917):853–859.

11/04/2026

“First” and “second” pain phenomena
BACKGROUND:
🔎Pain perception following a single noxious stimulus occurs as two temporally and qualitatively distinct sensations: a “first” pain, characterised as sharp, fast, and well-localised, and a “second” pain, which is slower in onset, dull, and more diffuse.
🔎Historically, these sensations have been attributed to activation of Aδ and C fibres respectively; however, the extent to which they are differentially represented at the cortical level has remained unclear.
📍An important study by Ploner et al. (2002) conducted laboratory-based experiments on humans to directly compare cortical processing of this “first” and “second” pain phenomena. They did so using magnetoencephalography (MEG) and a laser stimuli to selectively activate nociceptive fibers.
CORTICAL REPRESENTATION:
1️⃣“First” pain (A-delta mediated) was strongly associated with primary somatosensory cortex (S1) activation, which reflects sensory-discriminative processing.
2️⃣“Second” pain (C-fiber-mediated) was strongly associated with anterior cingulate gyrus (ACC) activation, which reflects affective-motivational processing.
INTERPRETATION:
⚠️There is no single pain centre in the brain, but rather multiple interacting and overlapping regions.
🔅“First” pain signals immediate threat and enables rapid withdrawal responses.
🔅“Second” pain sustains attention and promotes behaviours that support protection and recovery.
MW
Reference:
Ploner M, Gross J, Timmermann L, Schnitzler A. Cortical representation of first and second pain sensation in humans. Proc Natl Acad Sci U S A. 2002;99(19):12444–12448.

10/04/2026

Placebo:
Part 4: clinical uses in pain management
BACKGROUND:
🔎Placebo effects arise not from the substance itself, but from the therapeutic context (e.g., clinician interaction, expectations, treatment rituals). These effects are ubiquitous in healthcare, meaning they occur even when active treatments are used, contributing to overall clinical outcomes.
📍A peer reviewed commentary by Sanders & Finniss (2018) detail the clinical use of placebo in pain management. The authors acknowledge the evidence that highlights the neurobiological mechanisms and psychological processes that underpin this phenomenon.
🔆ENHANCE EXISTING TREATMENTS by optimising communication, clinician behaviour, and treatment context can augment analgesic outcomes.
🔆OPEN-LABEL (VISIBLE) ADMINISTRATION is more effective than hidden delivery due to placebo mechanisms, while avoiding ethical concerns associated with deception.
🔆THERAPEUTIC RITUAL OPTIMISATION through elements such as warm, empathetic communication, positive framing of treatment and effective patient engagement and understanding.
🔆ADJUNCTIVE USE of placebo alongside active treatments can improve outcomes without additional pharmacological burden.
🔆AWARENESS OF NOCEBO EFFECTS through negative expectations or poor communication can worsen pain or outcomes (nocebo), highlighting the importance of clinician behaviour.
SUMMARY:
📖Placebo effects are not inert or fake, but biologically and psychologically mediated responses embedded in all clinical care. In pain management, they play a significant role in modulating pain perception and treatment effectiveness.
📚Understanding and leveraging placebo effects can enhance outcomes, reduce reliance on medication, and improve patient care.
MW
Reference:
Sanders D, Finniss D. Clinical use of placebo in pain management. Pain Management Today. 2018;5(1):23-26

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