Marijuana, long known as a recreational drug, has earned some respectability with its growing reputation as a pain reliever for those who suffer from cancer, multiple sclerosis, and other ailments. And now, cannabis’s seedy reputation may go entirely to pot: a new strain called Avidekel preserves the drug’s medical properties but does not get users high.
The effects of various breeds of marijuana depend on their balance of the chemicals called cannabinoids. One cannabinoid, called tetrahydrocannabinol or THC, acts on the brain’s cannabinoid receptors to create the sensation of being high. While this feeling is the goal for recreational users, it can be an unwanted side effect for patients who smoke medical marijuana to relieve their pain and then find themselves unable to work, run errands in a car, or function normally until the drug’s effects wear off. The primary reason these users turn to marijuana in the first place is a different cannabinoid, called cannabidiol, which reduces inflammation without any psychoactive side effects.
Placebos are inactive treatments that shouldn’t, in some sense, have a real effect. And yet they often do. But the chemical basis of the placebo effect, despite its enormous importance, is still largely a mystery. A study published this week in Nature Medicine shows that cannabinoid receptors are involved in the placebo response to pain, which hasn’t been demonstrated before. The finding implies that the brain’s own endocannabinoids can fight pain, and actually do it via the same pathway as several compounds in the cannabis plant.
What’s the News: The best way doctors have to find out how much pain a patient’s in is to ask—but that approach can fall short when someone’s unable to speak, exaggerating or downplaying their condition, or just plain unsure how to rate their pain on a 10-point scale. Because of these problems with self-reporting, scientists have long been looking for an objective, physiological measure to quantify pain. A recent brain scanning study, in which the researchers could pick out painful experiences based on neural activity, brings that goal closer.
Left: normal rat disc. Right: engineered disc.
What’s the News: Researchers at Cornell University have now bio-engineered synthetic spinal discs and implanted them in rats. The implants provide as much spinal cushioning as authentic discs do, and improve with age by growing new cells and binding to nearby vertebrae, according to the study recently published in the journal PNAS. The research could someday help people with chronic lower back and neck pain from conditions like degenerative disc disease.
What’s the News: Researchers have pinpointed the molecule that makes sunburned skin so sensitive to pain, they reported yesterday in Science Translational Medicine. This finding could help scientists develop new painkillers not only for sunburn, but for chronically painful conditions such as arthritis.
Staring at your beloved’s face really can take the pain away and make everything better. A small but intriguing study has found that college students who looked at pictures of their beloveds felt less pain than others.
The study, published in PLoS One, was a collaboration between the pain researcher Sean Mackey and the love researcher Arthur Aron, who wondered how their fields might overlap in the brain. First they put out the call for volunteers in the early, passionate stages of a relationship.
The authors recruited 15 Stanford undergrads who were “wildly, recklessly in love,” said Mackey, adding that the recruitment process took “only days. It was the easiest study I’ve ever recruited for,” he said. “Within hours they were all banging on my door, ‘Study us! Study us!’ When you’re in that kind of love, you want the world to know about it.” [HealthDay News]
At the lab, the 15 volunteers either looked at photos of their beloveds, or at photos of an “equally attractive” acquaintance. In a third variation meant to test the impact of a mental distraction, the volunteers were asked to perform a cognitive task like listing sports that aren’t played with a ball. Then the researchers dialed up the pain, using a heated probe which they pressed against each person’s palm.
In a development that’s certain to stir passions in the abortion debate, the Royal College of Obstetricians and Gynaecologists in the UK published a report today on “fetal awareness.” The group states, citing a review of current research, that human fetuses cannot feel pain before 24 weeks.
The group’s reasoning, as described in a press release, is based on these points:
-The fetus cannot feel pain before 24 weeks because the connections in the fetal brain are not fully formed
-The fetus, while in the chemical environment of the womb, is in a state of induced sleep and is unconscious
-Because the 24 week-old fetus has no awareness nor can it feel pain, the use of analgesia is of no benefit
-More research is needed into the short and long-term effects of the use of fetal analgesia post-24 weeks [Royal College of Obstetricians and Gynaecologists]
This is certainly not the first debate over whether a fetus can feel pain. Fetal surgeries have led doctors to ask this question, as they determined whether anesthesia was appropriate and at what stage in development. As summarized in a 2008 New York Times Magazine article, researchers have looked at fetal flinch responses, heart rate, and levels of stress hormones. But any metric has remained controversial. Take stress hormones, for example. Do you say that any fetus that can release these hormones feels pain? Or do you wait until it develops the nervous system to register those hormones? Or do you say that an undeveloped nervous system makes the fetus more susceptible to pain, since it hasn’t developed the system to suppress it?
Phantom limb syndrome is an eerie condition, in which amputees have the physically painful sensation that their missing limbs are still present. Now, a small new study has shown that people can twist those ghostly limbs in anatomically impossible ways, while still feeling that the limb is real and present. In essence, each amputee’s brain reshaped his understanding of where his body was. The findings show that the brain can alter how we perceive our bodies all by itself, without input from our senses [Reuters].
Researchers had patients with “vivid phantoms” try to move their wrists in a physically impossible way—a 360 degree spin of the wrist around the long axis of the forearm—and found that 4 of the 7 patients could move their wrists this way. Some patients that were able to move their wrists later reported that their phantom hands were now more difficult to move from side to side because of changes in their phantom arms’ shapes.
With a little deception and an fMRI machine, scientists have traced the placebo effect to the spinal cord, according to new research published in the journal Science. The placebo effect, of course, is the well-known phenomenon in which patients who think they are getting medical treatment report that they feel better, even when they get only a sugar pill or other fake therapy [Los Angeles Times]. To test the limits of the placebo effect, researchers applied an anesthetic “lidocaine” cream to one arm, and a “control” cream to the other, making sure to tell the subjects which cream was which. The researchers applied a hot stimulus for 20 seconds to the skin where the each cream was applied. Participants said the “lidocaine” cream reduced pain by an average of 26 percent.
This would all be fairly straightforward had the researchers not been lying to their test subjects. You see, neither cream had active ingredients. They also primed a response by turning down the painful heat for the painkiller cream in a first test run, and so tricked volunteers into thinking that the cream would work the next time. But actual tests with an MRI scanner on involved the same level of heat for both creams. Volunteers nonetheless reported less pain with the painkiller cream [Popular Science].
The fMRI data backed up the participants’ pain perception. Normally when a person experiences pain, the dorsal horn area of the spinal cord near the lower neck will appear to be on fire with activity, but the fMRI scans showed nerve activity was reduced significantly when subjects believed they were getting the anesthetic [Reuters]. The researchers say this indicates that “psychological factors” can have an effect on pain outside of the brain. They hope to develop new treatments that can exploit the placebo effect’s painkiller effect.
80beats: 50% of U.S. Doctors Secretly Dose Their Patients—With the Placebo Effect
80beats: Fake Surgery Eases Spinal Pain as Well as the “Real” Thing
80beats: When Surgery Is Over, Anesthetics Actually Increase Pain
Image: flickr / fbaett
An increasingly common surgical procedure for repairing spinal fractures might not be all it’s cracked up to be–in fact, the surgery had the same effect on patient’s pain as a placebo, two studies report in the New England Journal of Medicine.
The technique, called vertebroplasty, involves injecting medical cement into a fractured spine bone to strengthen it. More than 38,000 such procedures are done in the United States every year and the number has been [increasing] rapidly, nearly doubling from 2001 to 2005 [Reuters]. But the new studies showed that the procedure alleviated pain about the same amount as a placebo “surgery,” in which the physicians tapped on the spine and piped in the smell of cement to make groggy volunteer subjects believe they were receiving the real thing.
Researchers found that 36 volunteers who received sham surgery did just as well as 35 who got the real operation. A separate test, of 131 people at 11 medical centers, … also found that sham surgery produced a comparable degree of pain reduction and movement [Reuters].