Psychology (9990) | Pain

Study Notes: Pain (Health Psychology Option 9990)

Welcome to the Pain chapter! Pain is one of the most fundamental experiences in health, but it’s surprisingly complex psychologically. In Health Psychology, we don't just look at the hurt—we explore how our minds and environments influence how we feel, measure, and manage pain. This is vital for understanding why people behave differently when they're ill.

Don't worry if some of the theories seem technical. We'll break them down using simple analogies!

3.3.1 Types and Theories of Pain

Pain isn't just one feeling; it serves a crucial purpose and comes in different forms.

Functions of Pain

The main function of pain is protection and survival. It's a warning signal that something is wrong, prompting us to withdraw from harm (like touching a hot stove) or rest an injury (like a sprained ankle).

Types of Pain

• Acute Pain: Short-term pain, usually severe, that disappears when the underlying injury or illness is healed. (Example: a paper cut or a broken bone.)
• Chronic Pain: Long-term pain (often lasting six months or more) that continues even after the initial injury has healed. This type of pain often involves strong psychological components. (Example: chronic back pain or fibromyalgia.)

Phantom Limb Pain (PLP)

This is a specific, fascinating, and often debilitating type of chronic pain. It is pain perceived to be coming from a limb (or other body part) that has been amputated. Even though the limb is gone, the brain still registers sensory information from that area.

Mirror Treatment for Phantom Limb Pain (PLP)

Since PLP is thought to be caused by a mismatch between the brain’s motor commands and the visual feedback it receives, treatments aim to "trick" the brain.

• The patient places their intact limb into one side of a box with a mirror, and the stump into the other side.
• The patient looks at the mirror reflection of their intact limb, making it appear that the phantom limb is still present and moving normally.
• When the patient moves the intact limb, they perceive the phantom limb moving, which can relieve cramping or distorted positions previously perceived.

Key Study Example: MacLachlan et al. (2004)
MacLachlan’s case study focused on using virtual reality (VR) as an alternative to the traditional mirror box therapy to treat PLP. The VR system provided visual feedback of the missing limb moving, often offering pain relief by resolving the sensory conflict in the brain. This shows an idiographic (individual case) approach to treating a unique pain problem.

Theories of Pain

How does the sensation of damage turn into the experience of pain? Psychologists have two main theories.

Specificity Theory (The Direct Route)

This is the oldest and simplest theory, often called the "telephone line" model.

• It suggests that specific sensory receptors (called nociceptors) exist purely for detecting pain.
• When tissue is damaged, these receptors send a direct, dedicated signal up specific nerve pathways to a "pain center" in the brain.
• Crucially, the intensity of pain is believed to be directly proportional to the amount of tissue damage.

Analogy: Think of it like an alarm system. If you break a window (damage), the window sensor (nociceptor) sends a direct, unalterable signal to the central alarm panel (brain).

Why is it Weak? Specificity theory fails to explain:

• Why pain persists (chronic pain) even after tissue is healed.
• Why psychological factors (like distraction or fear) can drastically change pain intensity.
• Phantom limb pain.

Gate Control Theory (GCT)

Developed by Melzack and Wall (1965), this theory is much more comprehensive and explains the role of psychological factors. It suggests there is a neural mechanism in the spinal cord that acts as a 'gate', which can either increase or decrease the flow of pain signals to the brain.

The 'Gate' Analogy: Imagine the pain pathway to the brain has a volume knob (the gate) located in the spinal cord. This knob can be turned up or down based on two main types of nerve fibres and messages coming down from the brain.

How the Gate Works (Step-by-Step):

1. Opening the Gate (More Pain): Small, slow nerve fibres (C fibres) transmit pain signals. Activity in these fibres opens the gate, increasing the perceived pain intensity. (This is the basic "ouch" message.)
2. Closing the Gate (Less Pain): Large, fast nerve fibres (A-beta fibres) transmit non-painful sensory information (like touch, pressure, or vibration). Activity in these fibres closes the gate, inhibiting the pain signal. (This is why rubbing a bruise makes it feel better—the touch signals close the gate.)
3. Central Control Mechanism: Signals coming down from the brain (cognitive factors) can also influence the gate.
   • Examples that Close the Gate: Positive emotions, distraction, relaxation.
   • Examples that Open the Gate: Anxiety, stress, fear, focusing on the pain.

Key Takeaway for GCT: Pain is not just a sensation; it is an experience shaped by sensory input, competitive sensory input (touch), and psychological state (cognition).

3.3.2 Measuring Pain

Measuring pain is challenging because it is inherently subjective (a personal experience). Health psychologists use various techniques to try and quantify this experience.

Subjective Measures: Clinical Interview

A practitioner asks the patient questions about their pain experience, including its location, duration, quality (e.g., stabbing, burning), and factors that make it better or worse. This gathers valuable qualitative data but relies heavily on patient honesty and memory.

Psychometric Measures and Visual Rating Scales

These methods aim to convert the subjective pain experience into measurable quantitative data.

McGill Pain Questionnaire (MPQ)

The MPQ is a comprehensive, widely used self-report tool developed by Melzack (1975). It measures three main dimensions of pain:

1. Sensory: Describes the quality of pain (e.g., sharp, throbbing, dull).
2. Affective: Describes the emotional response to the pain (e.g., terrifying, exhausting).
3. Evaluative: Describes the overall intensity of the pain (e.g., annoying, excruciating).

The patient selects words from lists to describe their pain, often providing a detailed pain profile that helps with diagnosis and treatment.

Visual Analogue Scale (VAS)

The VAS is a simple line, usually 10cm long, where one end is labelled 'No Pain' and the other is labelled 'Worst Possible Pain'. The patient marks a point on the line corresponding to their current pain level. This converts a subjective experience into a simple, easily comparable numerical value (measured in millimetres).

Key Study: Brudvik et al. (2016)
This study compared pain assessments by three groups: doctors, parents, and children (aged 6-12) in an outpatient setting. They used the VAS and other child-friendly scales. They found that there were discrepancies: doctors often underestimated the pain intensity reported by children, especially compared to the child's own rating or the parent's rating. This highlights the importance of using appropriate scales and considering multiple perspectives (e.g., the patient's own experience) when measuring pain, especially in children.

Behavioural/Observational Measures

These methods rely on observing outward signs of pain rather than relying on self-report, providing objective data.

UAB Pain Behaviour Scale

This scale is used to observe and quantify pain behaviours, often by clinicians or family members. Categories of observable behaviours might include:

• Facial expressions (grimacing).
• Verbalisation (moaning, complaining).
• Motor behaviours (guarding an area, limping).
• Use of aid (e.g., crutches).

Did you know? Observing pain is particularly useful for measuring pain in those who cannot verbally communicate, such as infants, people with severe cognitive impairments, or animals.

Key Takeaway for Measurement: Because pain is subjective, health psychologists must use a combination of techniques (interviews, rating scales, and observation) to get a full picture.

3.3.3 Managing and Controlling Pain

Treatments for pain fall into three main categories: biological, psychological (cognitive), and alternative.

Biological Treatment: Biochemical

This involves using pharmaceutical drugs to manage pain. These treatments work by interfering with the chemical processes (biochemicals) involved in pain signalling.

• Analgesics (painkillers) like paracetamol or aspirin reduce inflammation and interrupt chemical messages.
• Opioids (like morphine) bind to specific receptors in the brain and spinal cord to block the perception of pain, primarily used for severe acute or chronic pain.

Psychological Treatments: Cognitive Strategies

These techniques aim to use the central control mechanism from the Gate Control Theory—the brain's ability to influence the pain signal. They teach the patient how to control the 'gate'.

Attention Diversion (Distraction)

This involves focusing the patient's attention away from the pain signals, effectively using the cognitive input to close the gate.

• Example: Encouraging a child to play a video game during a painful medical procedure, or having an adult focus intently on solving a puzzle.

Non-Pain Imagery

The patient is instructed to imagine a pleasant, non-painful scene or sensation that is highly engaging, which diverts cognitive resources away from pain processing. This is a form of deep relaxation combined with cognitive distraction.

• Example: Imagining lying on a warm, deserted beach, feeling completely relaxed and safe.

Cognitive Redefinition (Cognitive Restructuring)

This technique challenges the patient's negative, catastrophic thoughts about their pain and replaces them with more adaptive or positive thoughts. It changes the meaning attached to the pain.

• Negative thought: "This pain is destroying my life, I can't cope."
• Redefinition: "The pain is uncomfortable, but it's manageable, and I have strategies to control it."

Alternative Treatments

These treatments often focus on natural processes or physical stimulation to reduce pain.

Acupuncture

A traditional Chinese method where fine needles are inserted into specific points on the body.
Theories: Psychologically, it may work as a distraction or through the release of natural pain-killing chemicals (endorphins). It might also activate large nerve fibres, effectively closing the gate.

Stimulation Therapy / TENS

Transcutaneous Electrical Nerve Stimulation (TENS) uses a small, battery-operated device that sends mild electrical impulses through electrodes placed on the skin near the site of pain.
How it Works: These mild electrical pulses stimulate the large nerve fibres (A-beta). According to the Gate Control Theory, this stimulation of non-painful signals successfully closes the 'gate' in the spinal cord, blocking the transmission of the pain signals to the brain.

Key Takeaway for Management: Effective pain management often requires a holistic approach, combining biological (medication) and psychological (cognitive distraction or TENS) methods to manage both the physical sensation and the mental experience of pain.