A World of Pain

In the US alone, chronic pain affects one in three people – more than heart disease, cancer, and diabetes combined – and costs more than $600 billion annually. But the subjective, contextual nature of chronic pain means that it is often difficult to treat – and easy to treat the wrong way.

BALTIMORE – Pain is ubiquitous in life. Inextricably bound to consciousness, it is an experience that all living creatures with advanced nervous systems share. For our ancestors, whose lives were fraught with danger, pain conferred an evolutionary advantage, signaling the need to separate oneself from its immediate source. But evolution has failed to keep pace with biomedical and technological advances, allowing chronic pain (pain that persists beyond an acute injury or condition) to become a disease in itself.

It is difficult to overestimate chronic pain’s societal impact. According to the US Institute of Medicine, one in three people suffer from chronic pain – more than from heart disease, cancer, and diabetes combined. Pain is the leading cause of disability, especially back pain among people under 45 years of age and joint pain in older individuals. In the United States alone, chronic pain is estimated to cost more than $600 billion annually.

Pain can be classified according to a variety of factors, such as duration or location. But the most useful categorization is based on mechanism. Nociceptive pain, which arises from damage to non-nervous tissue, occurs when, say, a person twists an ankle. An example of chronic nociceptive pain is arthritis. Neuropathic pain, by contrast, arises after a lesion or disease affects the nervous system. Nerve damage resulting from diabetes (diabetic neuropathy) and persistent pain after shingles (postherpetic neuralgia) are among the most common causes.