People living with chronic pain are more susceptible to depression than people with pain that is short-term in nature. Why? Experts point to two reasons—the first involves the negative effects pain has on a person’s life, called secondary losses, and the second involves the way the brain receives chronic pain messages.
Chronic pain can lead to other losses, which healthcare professionals call “secondary losses.” These secondary losses can lead to depression and even increased pain. For example, people living with chronic pain may experience:
Uncertainty. Not knowing if or when the pain will go away can lead to feelings of frustration and hopelessness.
Fatigue. Chronic pain can make it difficult to fall asleep and stay asleep, leading to fatigue and irritability during the day.
Isolation. People living with chronic pain often need to move slowly and carefully, which may lead them to spend more time at home than normal. People may miss out on social and recreational activities and begin to feel isolated.
Work and financial stress. If chronic pain prevents a person from working, he or she may encounter financial difficulties.
Medication side effects. Pain medications can sometimes cause gastrointestinal distress and a general feeling of mental dullness.
Decreased concentration. The pain is distracting, leading to memory and concentration difficulties.
Family strain. A spouse or child(ren) may need to take over responsibilities once carried out by the individual experiencing chronic pain. These changes can put stress on family relationships and lead the person in pain to feel guilty.
Decreased sex drive. Sex can be painful or sexual drive can be diminished, which can put stress on a person’s romantic relationship.
Moreover, people with chronic pain may harbor a feeling of perceived injustice—that it is unfair that they must live with chronic pain while others do not.1 Understandably, chronic pain may lead to feelings of despair, hopelessness, and other symptoms of a major depression or clinical depression.
Chronic pain pathways in the brain
In addition to secondary losses, there is another reason chronic pain is associated with depression. Research has demonstrated that once pain signals reach the brain, they may be directed along different pathways depending on the type of pain:2
Acute pain messages are relayed to the brain’s thalamus and cortex. Acute pain messages reach the cortex very quickly and prompt the individual to take action to reduce the pain or threat of injury (e.g. removing your hand from the hot stove).
Chronic pain messages are relayed to the brain’s hypothalamus and the limbic system. The hypothalamus is responsible for the release of certain stress hormones in the body. The limbic system is the brain area where emotions are processed.
In other words, the chronic pain signals pass through the areas of the brain that control stress and emotions. This is one reason why chronic pain is often associated with stress, depression, and anxiety.