The overlap between mood disorders and pain is especially marked in chronic pain syndromes: psychiatric or mental health conditions not only have an influence on pain intensity but also lead to greater degree of disablement from the condition.
Chronic pain and anxiety is a complex area as knowing what is cause and effect can be tricky. Researchers once believed that the relationship between pain and mood disorders such as anxiety resulted primarily from psychological factors. However as research expands understanding of the complex interrelationship between the body, mind and nervous system, it is becoming clear that pain shares some biological mechanisms with anxiety.
Anxiety disorders are second only to depression in psychological comorbidity amongst those with chronic pain. Generalized Anxiety Disorder has been found to be the most frequently diagnosed anxiety disorder amongst those with chronic pain and studies show other strong associations with panic disorder, agoraphobia and post-traumatic stress disorder. Where individuals have more than one comorbid mental health issue, the level of disability from the chronic pain condition increases significantly and where one or more physical disorders is present, a comorbid anxiety disorder diagnosis has been associated with an increased likelihood of disability even after adjusting to the condition.
Common chronic pain conditions associated with anxiety
This is a general term used to describe many conditions affecting the musculoskeletal system but specifically the joints and surrounding tissues. There are many forms but the two most well-known ones are rheumatoid arthritis and osteoarthritis.
Anxiety and other mental-health conditions are widespread in arthritis sufferers, and often especially in younger patients.
This is a long-term condition that causes pain, hypersensitivity and fatigue but can also lead to issues with concentration and memory as well as difficulties sleeping. It is thought that as many as one in five sufferers also suffer from an anxiety disorder. One study found that women with fibromyalgia are four to five times more likely to have been diagnosed with obsessive-compulsive disorder, generalized anxiety disorder or post-traumatic stress disorder.
Migraines are severe headaches that recur frequently and can last for hours or days. They are often accompanied by other symptoms such as photosensitivity and nausea or vomiting or sometimes preceded by sensory warning signs termed 'auras'. As many as half of all chronic migraine sufferers also have anxiety.
Back or neck pain
This appears to be more frequent in those with mood disorders such as anxiety. Back pain may be caused by a number of different conditions but is often associated with being overweight, lifting injuries. Those with back or neck pain are two to three times more likely to have experienced panic disorder, agoraphobia, or social anxiety disorder, and almost three times more likely to have had generalized anxiety disorder or post-traumatic stress disorder.
Irritable Bowel Syndrome (IBS)
IBS is one of the most common gastrointestinal disorders, with up to one in five of the population experiencing it at some point during their life. IBS is not a psychological disorder but has become strongly associated with both stress and anxiety.
Anxiety as a cause of chronic pain
There are many reasons that anxiety might lead to chronic pain. When we’re stressed, the body secretes stress hormones, which are stimulants, into the bloodstream One of the tasks stress hormones perform is to cause muscles in the body to contract (tighten). Where this response is caused by anxiety rather than the actual physical threat, this tightening of the muscles can be in places such as the back where it causes pain.
Additional ways in which anxiety might be the cause of chronic pain is inflammation. When stressed, our bodies produce the hormone cortisol which, over the long term can lead to chronic systemic inflammation. Prolonged stress may also have a role to play in a metabolic syndrome which, in turn, is linked to several indicators of systemic inflammation and musculoskeletal conditions.
Stress also results in the production of adrenaline – a key part of the fight or flight mechanism. This can cause vasospasm which is a spasm of the arteries which can cause migraines. Stress and anxiety are also associated with the clenching or grinding of teeth, known as bruxism, and this jaw tension can also lead to migraines.
Chronic stress can also lead to a heightened sensitivity to pain, known as hyperalgesia. Here, pain sensitivity can reach the level that so much that persistent and intense pain is felt even in the absence of a physical injury.
Chronic stress has also been shown to have an impact upon the central nervous system. The complex system of communication between neurons works efficiently in a healthy individual but issue can arise when the nervous system becomes stress-response hyperstimulated.
Anxiety may also predispose us to certain chronic pain conditions: one such example is complex regional pain syndrome. This condition is triggered by a physical injury but the pain and injury is disproportionate to the nature of the injury. As with other conditions where personality-type has been found to have a bearing on an individual's general health, several studies have found that psychological factors have an impact on the development of the condition.
Psychologically, anxiety is also thought to be an important mediator in cognitive constructs that can exacerbate the experience of pain. These include:
Catastrophizing. Catastrophizing is where someone focuses on the worst case scenario in any given situation, a common feature in anxiety disorders. A tendency to catastrophize is linked to greater impairment from a chronic pain condition and increased pain. It is used as a measure when assessing the likely outcome for chronic pain individuals.
Hypervigilance. This is obviously common in anxiety but when it applies to pain it leads to greater focus upon pain levels and general immersion in the sensation of pain.
Fear avoidance is where someone restricts movements or activities for fear of repeating the injury that lead to the pain and is known as kinesophobia. When an individual needs to engage in rehabilitation programmes, this can prove especially problematic.
Chronic pain as a cause of anxiety
It is not surprising perhaps that when you have a chronic illness, you may be more inclined to experience mental health issues. For example, when your physical movement is restricted, this can cause distress; and you may worry about your future and health in the long-term. If you experience episodic pain with a condition that “flares up” at times, you may become anxious worrying about when the next “attack” will be. This can lead to a sense of helplessness and feelings of unpredictability and uncertainty, such as can be seen in anxiety.
Interestingly, the experience of pain itself over the long-term can “rewire” your brain. When you first experience pain, pain-sensitivity circuits are activated; but over the long-term, this activity moves to circuits that process emotions. One study found that neurons thought to produce negative emotions became activated shortly after a chronic-pain inducing injury.
Anxiety and pain perception
Comorbidity is a complex area where knowing which came first can be complicated to ascertain. It is clear that there may be shared vulnerabilities for disorders and that comorbidity can lead to mutual maintenance.
It presents key challenges for treatment as when pain overlaps with a mood disorder, the focus on pain can mask awareness that an anxiety disorder is present. Unfortunately, even when both types of problems are correctly diagnosed, they can be notoriously difficult to treat.