What is the Role of Age and Gender in
Pain?
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Gender and Pain
It is now widely believed that pain affects men and women
differently. While the sex hormones estrogen and testosterone
certainly play a role in this phenomenon, psychology and
culture, too, may account at least in part for differences in
how men and women receive pain signals. For example, young
children may learn to respond to pain based on how they are
treated when they experience pain. Some children may be cuddled
and comforted, while others may be encouraged to tough it out
and to dismiss their pain.
Many investigators are turning
their attention to the study of gender differences and pain.
Women, many experts now agree, recover more quickly from pain,
seek help more quickly for their pain, and are less likely to
allow pain to control their lives. They also are more likely to
marshal a variety of resources-coping skills, support, and
distraction-with which to deal with their pain.
Research
in this area is yielding fascinating results. For example, male
experimental animals injected with estrogen, a female sex
hormone, appear to have a lower tolerance for pain-that is, the
addition of estrogen appears to lower the pain threshold.
Similarly, the presence of testosterone, a male hormone, appears
to elevate tolerance for pain in female mice: the animals are
simply able to withstand pain better. Female mice deprived of
estrogen during experiments react to stress similarly to male
animals. Estrogen, therefore, may act as a sort of pain switch,
turning on the ability to recognize pain.
Investigators
know that males and females both have strong natural
pain-killing systems, but these systems operate differently. For
example, a class of painkillers called kappa-opioids is named
after one of several opioid receptors to which they bind, the
kappa-opioid receptor, and they include the compounds
nalbuphine (NubainŽ) and butorphanol (StadolŽ).
Research suggests that kappa-opioids provide better pain relief
in women.
Though not prescribed widely, kappa-opioids are currently used for relief of labor pain and in general work best for short-term pain. Investigators are not certain why kappa-opioids work better in women than men. Is it because a woman's estrogen makes them work, or because a man's testosterone prevents them from working? Or is there another explanation, such as differences between men and women in their perception of pain? Continued research may result in a better understanding of how pain affects women differently from men, enabling new and better pain medications to be designed with gender in mind. top
Pain in Aging and Pediatric Populations: Special Needs and Concerns
Pain is the number one complaint of older Americans, and one in five older Americans takes a painkiller regularly. In 1998, the American Geriatrics Society (AGS) issued guidelines
* for the management of pain in older people. The AGS panel addressed the incorporation of several non-drug approaches in patients' treatment plans, including exercise. AGS panel members recommend that, whenever possible, patients use alternatives to aspirin, ibuprofen, and other NSAIDs because of the drugs' side effects, including stomach irritation and gastrointestinal bleeding. For older adults, acetaminophen is the first-line treatment for mild-to-moderate pain, according to the guidelines. More serious chronic pain conditions may require opioid drugs (narcotics), including codeine or morphine, for relief of pain.
Nonsteroidal agents, and especially acetaminophen, are most often prescribed for control of pain in children. In the case of severe pain or pain following surgery, acetaminophen may be combined with codeine.
* Journal of the American Geriatrics Society (1998; 46:635-651).
A Pain Primer: What Do We Know About Pain?
We may experience pain as a prick, tingle, sting, burn, or ache. Receptors on the skin trigger a series of events, beginning with an electrical impulse that travels from the skin to the spinal cord. The spinal cord acts as a sort of relay center where the pain signal can be blocked, enhanced, or otherwise modified before it is relayed to the brain. One area of the spinal cord in particular, called the
dorsal horn , is important in the reception of pain signals.
The most common destination in the brain for pain signals is the thalamus and from there to the cortex, the headquarters for complex thoughts. The thalamus also serves as the brain's storage area for images of the body and plays a key role in relaying messages between the brain and various parts of the body. In people who undergo an amputation, the representation of the amputated limb is stored in the thalamus. (For a discussion of the thalamus and its role in this phenomenon, called phantom pain,
Pain is a complicated process that involves an intricate interplay between a number of important chemicals found naturally in the brain and spinal cord. In general, these chemicals, called neurotransmitters, transmit nerve impulses from one cell to another.
There are many different neurotransmitters in the human body; some play a role in human disease and, in the case of pain, act in various combinations to produce painful sensations in the body. Some chemicals govern mild pain sensations; others control intense or severe pain.
Endorphins and enkephalins are other natural painkillers. Endorphins may be responsible for the "feel good" effects experienced by many people after rigorous exercise; they are also implicated in the pleasurable effects of smoking.
Similarly, peptides, compounds that make up proteins in the body, play a role in pain responses. Mice bred experimentally to lack a gene for two peptides called tachykinins-neurokinin A and substance P-have a reduced response to severe pain. When exposed to mild pain, these mice react in the same way as mice that carry the missing gene. But when exposed to more severe pain, the mice exhibit a reduced pain response. This suggests that the two peptides are involved in the production of pain sensations, especially moderate-to-severe pain. Continued research on tachykinins, conducted with support from the NINDS, may pave the way for drugs tailored to treat different severities of pain.
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