While acute pain is a normal sensation triggered in the nervous system to alert you to possible injury and the need to take care of yourself, chronic pain is different. Chronic pain persists. Pain signals keep firing in the nervous system for weeks, months, even years.

There may have been an initial mishap -- sprained back, serious infection, or there may be an ongoing cause of pain -- arthritis, cancer, ear infection, but some people suffer chronic pain in the absence of any past injury or evidence of body damage. Many chronic pain conditions affect older adults.

Common chronic pain complaints include headache, low back pain, cancer pain, arthritis pain, neurogenic pain (pain resulting from damage to the peripheral nerves or to the central nervous system itself), psychogenic pain (pain not due to past disease or injury or any visible sign of damage inside or outside the nervous system).

Treatment for Chronic Pain

Medications, acupuncture, local electrical stimulation, and brain stimulation, as well as surgery, are some treatments for chronic pain. Some physicians use placebos, which in some cases has resulted in a lessening or elimination of pain. Psychotherapy, relaxation and medication therapies, biofeedback, and behavior modification may also be employed to treat chronic pain.

Prognosis for Chronic Pain

Many people with chronic pain can be helped if they understand all the causes of pain and the many and varied steps that can be taken to undo what chronic pain has done. Scientists believe that advances in neuroscience will lead to more and better treatments for chronic pain in the years to come.

Research on Pain

Certain amino acids have been found to raise pain thresholds and increase tolerance to pain. One of these, a synthetic amino acid called D-phenylalanine (DPA), decreases pain by blocking the enzymes that break down endorphins and enkephalins, the body’s natural pain-killing chemicals. DPA may also produce pain relief by other mechanisms, which are not well understood.

Reference for Chronic Pain Article

Ehrenpreis S. Analgesic properties of enkephalinase inhibitors: animal and human studies. Prog Clin Biol Res 1985;192:363–70.

Guisti P, Carrara M, Cima L, Borin G. Antinociceptive effect of some carboxypeptidase A inhibitors in comparison with D-phenylalanine. Eur J Pharmacol 1985;116:287–92.

Walsh NE, Ramamurthy S, Schoenfeld LS, Hoffman J. D-phenylalanine was not found to exhibit opiod receptor mediated analgesia in monkeys. Pain 1986;26:409–

National Institutes of Health