Friday October 15 2010
High-intensity pain was cut by 12.9% when viewing a loved one
“Love can block pain in a similar way to morphine,” the Daily Mirror reported. It said that a study has found that feelings of love, triggered by seeing a lover's picture, flooded volunteer’s brains with painkilling dopamine.
This small study in 15 volunteers found that viewing pictures of a romantic partner while undergoing different levels of painful stimuli reduced their feelings of pain. Reduced pain levels were also associated with the activation of certain “reward-processing” regions of the brain, similar to the process that occurs with pain-relieving medicines.
The researchers aimed to explore the possible neural pathways by which viewing pictures of a romantic partner can reduce subjective pain levels. They say that a better understanding of these “analgesic pathways” may identify new methods for producing effective pain relief.
While the findings may contribute to our overall knowledge of the neural pathways involved in pain, they tell us little about how love affects pain or trauma in real life. The newspaper may also have overstated the effects the volunteers experienced.
Where did the story come from?
The study was carried out by researchers from Stanford University in California, and the State University of New York. The research was funded by several organisations, including the Arthritis Foundation, and the National Institutes of Health. The study was published in the peer-reviewed journal PLoS ONE.
It was covered widely in the media, which compared the effect of love to that of pain-relieving drugs. However, the Daily Mail overstated the study’s findingsby claiming that the “first flush of love is all you need to overcome pain”.
What kind of research was this?
This experimental, laboratory study investigated the relationship between feelings of romantic love, pain relief and activation of “reward systems” in the brain.
The researchers say that the early stages of a romantic relationship are characterised by intense feelings of euphoria. Studies of neuro-imaging has linked these feelings to activation of reward systems in the human brain, while animal research has shown that activating these reward systems with drugs can substantially reduce pain.
Here, they scanned the brains of 15 volunteers with functional Magnetic Resonance Imaging (fMRI) to see whether viewing pictures of a human partner was associated with “neural activations in reward-processing centers”.
What did the research involve?
The researchers recruited 15 left-handed students (eight women and seven men) aged 19 to 21 years, who were all in the first nine months of a romantic relationship. The students were exposed to different degrees of pain, provided by a computer-controlled heat block placed in the palm of the left hand, while completing three separate tasks:
- viewing pictures of their romantic partner
- viewing pictures of an equally attractive and familiar acquaintance
- completing a word-association distraction task; previous research has demonstrated that performing this task can reduce pain
The students’ brains were scanned with fMRI during each of these tasks. The researchers then analysed the neural activity that had taken place during each of the tasks, and at each of the different levels of pain.
All the students described themselves as intensely in love and had also met external criteria for being passionately in love, as measured by the Passionate Love Scale (PLS). Each student provided three photos of their partner and three of an acquaintance of the same gender and attractiveness, whom the participants had known for the same length of time as their partner and for whom they had no romantic feelings. Attractiveness of both partners and acquaintances were also rated independently by eight individuals not otherwise involved in the study. (The researchers explain they tried to balance attractiveness of each partner with the acquaintance, since attractiveness has been shown to independently activate neural reward systems).
At the beginning of the scan session, the researchers determined subjective pain thresholds for each volunteer by asking them to hold the heat block while it gradually got hotter. The volunteers were asked to rate when the pain reached certain levels, ranging from ‘no pain at all’ to ‘worst pain imaginable’.
During the first two tasks, participants were asked to focus on the pictures and think about the person in them while they were being scanned. In the distraction task, they were given a phrase and asked to think of as many responses as possible. Each task was performed under periods of no pain, moderate pain and high pain. The volunteers rated their subjective pain levels using the button box and a visual analog scale.
The researchers used standard techniques to analyse the effects of the tasks on self-reported pain.
What were the basic results?
The researchers found that viewing pictures of a loved partner and completing a distraction task both significantly reduced self-reported pain. But viewing pictures of an acquaintance had no effect on pain levels.
- For moderate-intensity heat, pain levels were reduced by an average of 36% while doing a distraction task, and by 44.7% while viewing pictures of a partner.
- For high-intensity heat, pain levels were reduced by an average of 12.9% while doing the distraction task, and by 12.1% while viewing pictures of a partner.
Greater pain-relief while viewing pictures of a romantic partner were associated with increased activity in several “reward-processing” regions of the brain, and with decreases in activity in pain processing regions. However, the scan showed no changes in brain activity during the distraction task.
How did the researchers interpret the results?
The researchers say these results suggest that activating “reward systems” in the brain by means other than drugs – such as viewing pictures of a romantic partner – can reduce the experience of pain.
They also conclude that the neural processes involved in relieving pain while viewing pictures of a romantic partner are distinct from those involved with pain relief induced by a word distraction exercise.
As the researchers point out, their study had a number of limitations. For example, there was no objective measure of how much attention each participant paid to each task (e.g. eye-tracking).
The small sample size makes it impossible to measure possible gender differences in the pain-relieving effect of romance. In addition, six of the 15 volunteers correctly guessed the purpose of the experiment, which may have affected their responses. The researchers also point out that there is “considerable individual variability” in pain relief when looking at pictures of the beloved.
These findings may further our understanding of the neural pathways involved in relieving pain. However, the study is greatly limited by its small size, and the fact that the experimental pain scenario can tell us little about the effects of pain or trauma. in real-life scenarios.