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PAIN AND EMOTIONAL DISTRESS

Forensic evaluators typically confront multiple risk factors that contribute to impairment in every day functioning, as well as poor or inconsistent performance on neuropsychological test batteries. Often in forensic settings, neuropsychologists are asked to determine a cause and effect relationship, particularly examining the role depression may play in impairing every day functioning and test performance in individuals suffering from mild traumatic brain injury and/or chronic pain. This legal update provides a brief overview and references concerning current knowledge of the relationship between pain and emotional distress.

The International Association for the Study of Pain defines pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage.” The definition further clarifies that an emotion is a sense of “cognitive appraisal and reaction to stimuli often accompanied by physiological arousal and related behavior.” Taking these two phenomena into account, pain appears to be an individual experience with multiple variables, including emotional distress, contributing to perception of severity and impairment.

What precisely is the role of emotional distress and functional disruption in individuals experiencing chronic pain? Is clinical depression caused by chronic pain? This hypothesis is supported by some of the research literature concerning depression. Pain is a phenomena characterized by marked uncertainty and unpredictability. Individuals suffering chronic pain are never quite certain when they will or will not experience pain, the severity of their pain or an effective strategy to reduce pain. They are often uncertain how much or how little pain will interfere with daily activities of life or how long they will experience pain until relief is experienced. This formula of uncertainty leads to a sense of helplessness and often hopelessness, characteristically the fuel for clinical depression.

It is also reasonable to hypothesize that the experience of pain is intensified even to the extent of being caused by chronic, emotional distress experienced by individuals suffering from clinical depression. This theory too has generated some research support. Finally, because pain is clearly a subjective and private experience, in the legal arena, it is often difficult to quantify and objectively measure.

Intense emotions often lead to physiological arousal caused by activation of the autonomic nervous system. Though chronic pain may not directly elicit an autonomic nervous system response, the sense of helplessness and anxiety experienced by chronic pain likely initiates such a response which then leads to further mood changes. Additionally, an individual’s belief about their pain, resources to manage pain as well as other life phenomena clearly play a role in the course of pain and illness. Because pain produces a number of reactions, typically anxiety and cumulatively a sense of helplessness and thus depression, these likely further lower pain threshold.

Researchers have demonstrated a strong relationship between chronic pain and depression. Studies estimate that 30% to 100% of chronic pain patients experience clinical depression with most studies reporting at least 50% of patients suffering from this condition. Individuals presenting with depression also describe a much higher rate of chronic pain than in those in the general population.

The role of anxiety in pain has also been studied. At least 20% of chronic pain suffers experience generalized anxiety. Anxiety has been hypothesized to contribute up to 50% of the variability of an individual’s report of pain.

Although it is beyond the scope of this brief review to discuss the physiology of pain, cortisol (a glucocorticoid secreted by the adrenal glands) may offer an explanation and a link between pain and depression. The hippocampus and amygdala appear to be the key areas of the brain involved in the experience of adverse emotions. The hippocampus acts as a brake on cortisol release during stress. When the hippocampus doesn’t act appropriately, cortisol is not suppressed. Cortisol may be excessively released due to pain. Failure to suppress cortisol has been a consistent report for adults with depression.

These studies generally provide evidence suggesting that depression in chronic pain sufferers is more likely a consequence than a cause of their pain. Though there is likely a bi-directional relationship, many chronic pain suffers would likely not be depressed absent pain. Further, individuals with pre-trauma histories of depression are at greater risk to experience depression in the face of chronic pain. In patients with depression without pain, negative thoughts are likely a product rather than a precursor of depressed mood. It is more likely that in pain sufferers, cognitive distortions, particularly the experience of helplessness and hopelessness produces their depression.

In one of the few prospective studies, depression has been found as a risk factor for the onset of chronic pain. A research group in 1993 interviewed over 1,000 patients concerning their history and age of onset of multiple types of pain. These individuals were re-interviewed three years later to measure site specific first onset rates in those reporting no current pain conditions at baseline. The results demonstrated that the effects of depression on the onset of pain though inconsistent across sites and not stronger with increasing severity of depression were generally significant. Overall, however, the presence of a pain condition at baseline was a more consistent predictor of the development of a new pain condition.

In the forensic setting, a comprehensive neuropsychological evaluation of individuals suffering from traumatic brain injury must include a screening and if needed a thorough evaluation for pain and post trauma psychiatric disorders. While these three conditions disrupt daily functioning and cognitive efficiency leading to significant impairment in daily life, it has been my experience that in individuals presenting with the typical TBI “unholy trinity” of cognitive impairment, chronic pain and emotional distress, unless the last two are addressed, symptoms resulting from the first rarely improve.