To provide good healthcare, it is essential to understand symptoms. Symptoms are very common and ambiguous. They are influenced by psychological factors.

A symptom refers to any variation in physiological or emotional state that is interpreted as unusual and labelled as potentially harmful. Appraisal and interpretation are central. However, people are not good at interpreting their physical state accurately.

There are different psychological factors that influence the perception and interpretation of symptoms:

1. Attention
   The degree of attention to the internal physical state has a strong influence on the perception of symptoms. Attention has limited capacity and internal states have to compete for attentional resources. People are more likely to report symptoms in boring environments. The perception of symptoms can be lowered by not focusing on internal states.
2. Environment
   People are less likely to perceive symptoms in distracting environments whereas people are more likely to perceive symptoms in boring environments. This is closely tied to attention.
3. Individual differences in the interpretation of symptoms
   There are individual differences in the degree to which people pay attention to internal states and which types of symptoms they are more likely to attend to. This is influenced by schemas about which illnesses one is vulnerable to. These schemas are influenced by past experience of illness and others’ attitudes to illness. The perceived cause of symptoms is important. The attributional styles of people influences how people respond to symptoms.
4. Emotion
   Strong emotion is accompanied by physiological changes that can be misinterpreted as symptoms. Negative emotions are related to an increased report of symptoms and it is related to associating symptoms with illness more often. The current emotional state influences attention to (1), appraisal (2) and interpretation of symptoms (3).

Due to the demands of the immediate situation and due to changes in the physical state (e.g. endorphins), it is possible that people do not notice a serious injury right away and carry on. Anxiety makes people hypervigilant and sensitive to threat. This can lead to a heightened perception of symptoms.

There is a delay in seeking help (1), overuse or underuse of healthcare services (2) and compromised treatment (3) due to the misperception of symptoms. Education about symptom recognition, biases and management can lead to better treatment outcomes.

Medically unexplained symptoms (MUS) refer to persistent bodily symptoms with functional disability but no explanatory structural or other pathology. It is often seen as somatoform disorders. However, conditions that are poorly understood are also often put into this disorder. MUS is more common in women, low SES and in people with a history of child abuse. MUS are strongly associated with psychological disorders (e.g. anxiety; depression). The presence of physical symptoms is associated with psychological morbidity.  

Symptoms and disability are perpetuated by cognitive and behavioural factors (e.g. increased attention to symptoms; avoidant coping).

Pain refers to a distressing experience that is associated with actual or potential tissue damage and which has sensory, emotional, cognitive and social elements. Nociception is the stimulation of peripheral pain receptors which sends messages to the central nervous system. Sensation refers to how pain is interpreted. Suffering refers to the perceived pain, distress and disability that can arise from pain and related factors.

Pain threshold refers to the point at which a stimulus becomes painful and this is similar for most people. Pain tolerance refers to the degree to which a painful stimulus can be tolerated and this varied widely between individuals. Acute pain refers to pain which is necessary to protect us from damage or infection. Chronic pain can lead to changes to the neural pathway of pain leading to the perception of pain even when there is no physical injury. This can be prevented by early intervention.

Pain consists of nociception (1), pain sensations (2), thoughts (3), emotions (4), pain behaviours (5) and suffering (6).

Pain occurs in a social context and there are different aspects to it. The gate theory of pain states that there is a synaptic gate between peripheral nerves and neurons in the spinal cord. Pain signals from peripheral nerves compete with other neural signals to get through the gate. The gate can be open or closed by physical or psychological factors. This theory states that stimulating another part of the body during pain can reduce perceived pain. The neuromatrix model of pain states that pain is due to interacting neural networks with somatosensory, limbic and cognitive components.

Conditioning approaches to chronic pain focus on the role of operant conditioning in behavioural responses to pain. Long-term pain behaviours are shaped by how others react to these behaviours. Cognitive-behavioural approaches to chronic pain incorporate behavioural factors (e.g. operant conditioning) and individual factors (e.g. perceived pain). The fear-avoidance model states that if people catastrophize about their pain, there is a greater fear of pain, greater focus on pain and restricted functioning (e.g. people avoiding activities that might elicit pain). The functional-contextual approach focuses on the processes and function of thoughts and behaviours rather than the content of thoughts. There is a focus on psychological flexibility. Treatment is thus focused on improving functioning rather than countering pain.

The communal coping model (CCM) looks at the relationship between pain and catastrophizing thoughts and behaviour. It states that some people may be predisposed to dealing with distress by catastrophizing in order to communicate distress and attempt to increase social proximity and support from others. The social function of catastrophizing is the most important aspect.

Pain management programmes generally reduce pain, depression or negative emotions and abnormal pain behaviours. It can also lead to more successful coping, increased activity and improved social functioning.

The placebo effect refers to receiving a fake treatment and improving due to the expectancy of improvement. Placebo effects are more powerful for conditions with psychological components (e.g. pain) and not effective for disorders with a clear and simple biological basis (e.g. infections). The characteristics of placebos affect how well they work (e.g. injection versus pills). The nocebo effect refers to people developing symptoms that fit their beliefs when they have not been exposed to a pathogen.

Classical conditioning and modelling could potentially explain the placebo and nocebo effects. Placebos work through a person’s expectations. The effectiveness of many active drugs can be increased by presenting it in the right manner. Placebos can also result in positive change without any negative side effects.

People hold conscious beliefs about illness which will determine the action a person chooses to take (1), which information they will give to the healthcare professional (2), whether they adhere to treatment (3) and their emotional, behavioural and cognitive response to illness (4). Illness beliefs are not necessarily accurate or coherent.

Illness representation refers to people’s organized sets of beliefs about the experience, impact, effect and outcome of an illness. This is unique for each individual and is shaped by many factors. There are five main dimensions of illness representations:

1. Illness identity
   This refers to the way a person labels the illness and the symptoms.
2. Timeline
   This refers to the length of time that a person believes the illness will last and the patterns it will take.
3. Cause
   This refers to what the person thinks caused the symptoms or illness.
4. Control
   This refers to beliefs about whether the illness can be prevented, controlled or cured.
5. Consequences
   This refers to beliefs about the effects of the illness.

The self-regulation model of illness behaviour is a model which states that illness representations can affect the way a person copes with their symptoms. People are less likely to adhere to treatment for an illness of which there are no concrete symptoms. The self-regulation model of illness beliefs can be useful when treating people. It can be useful to explore and change a person’s illness beliefs. Self-management interventions refer to interventions which target a person’s beliefs and coping in order to help them manage their illness and treatment effectively.