“Rats help each other because they care,” says Peggy Mason, a professor of neurobiology at the University of Chicago. Neuroscientists at the University of Chicago recently conducted an experiment suggesting that midazolam, an anti-anxiety medication, reduces empathy in rats.
This research builds on a study conducted in 2011, in which scientists saw rats empathize with each other. In the 2011 experiment, two rats, which had been cage mates, were placed in a special test area together. One was trapped in a restrainer device while the other was free to move about the cage, hearing and seeing his trapped mate. The restrainer device could only be opened from the outside. Recent experiments use the same test, but this time researchers injected the test rats with the anxiety drug midazolam.
Researchers observed that the rats injected with midazolam showed less empathy than control rats that did not receive an injection. Unlike the control group, the drugged rats were unlikely to open the restrainer device to free their cage mates even though they were still physically capable of opening the device. When researchers placed chocolate chips in the restrainer device, the test rats regularly opened the door.
Stress changes the adrenal glands and sympathetic nervous system, which increases heart rate and blood pressure. To see if the rats were responding to these physical changes, the researchers conducted another series of experiments, this time giving the rats the beta-blocker nadolol, which prevents bodily signs of stress response. These rats behaved just as altruistically as their unmedicated peers. They were acting on empathy, not a physical stress reaction.
The researchers also created a statistical model to see if the rats actually found helping each other rewarding, or if they simply became more comfortable in the testing area and better at opening the restrainer device. Haozhe Shan, an undergraduate student at the university, calculated the probability of the rats helping each other and projected this data over 10,000 simulations. Comparing the simulated data with the data from the experiments, Shan saw that the unmedicated rats helped their cage mates more often than the simulations predicted: their behavior was being reinforced. This was not the case with rats given midazolam. Repeating the experiment did not make them more likely to help their companion, regardless of whether they had helped the previous day. According to Shan, “We take that as a sign that the rats given midazolam don’t find the outcome rewarding, presumably because they didn’t find it a troubling situation in the first place.”
When the rats were first exposed to their trapped cage mate, the researchers tested their levels of corticosterone, a stress hormone. The rats with high levels of this hormone were least likely to provide assistance. This goes with what researchers already know about stress responses in humans: people under high stress are not motivated by their intense physiological responses, they are immobilized by it.
This study on midazolam highlights a problem that occurs with many other drugs used to treat anxiety, such as selective serotonin reuptake inhibitors (SSRIs): patients experience a “blunting” of their emotions, making the patients unsympathetic towards others. Doctors often prescribe SSRIs for anxiety disorders, especially anxiety with comorbid depression.
In a study published in the August 2009 issue of The British Journal of Psychiatry, researchers interviewed 38 patients about their undesirable emotional responses to SSRIs. One of the eight themes researchers identified in this study was emotional detachment. Most of the patients they interviewed experienced this SSRI symptom describing it as a feeling of being “in limbo” or “a spectator rather than a participant.” Others described the feelings as “unreality” or “robotic.” Most significantly, these patients “felt reduced sympathy and empathy” to such an extreme that they even felt detached from their children and partners while on these medications.
Perhaps surprisingly, patients had mixed responses to their emotional detachment from others. To some it was undesirable, but to others it was beneficial because it blunted the intensity of “negative emotions and highly charged situations.”
Because patients suffering from anxiety often complain that their medications leave them feeling emotionally “numb,” it is in the interest of patient health and well-being to explore the realm of empathy in patients undergoing drug treatment for anxiety. According to the CDC, 15% of individuals will experience some type of anxiety disorder in their lifetime.
Guest article edited by Ross Cummings.