A lot of us associate the word serotonin—a neurotransmitter that allows brain cells to communicate back and forth—with sleep and with stress. And while it is partly responsible for how much sleep we got last night and how stressed we are at work today, there’s still much to learn about the chemical nerve. Researchers from Imperial College London think they’re onto something as they argue that a two-pronged model of how serotonin acts be incorporated into its present understanding. They believe that this updated model will transform the way we treat mental illnesses, such as depression, addiction, and anxiety.
Serotonin acts through a variety of sites called receptors, two of which are especially important: serotonin 1A and 2A. And drugs like antidepressants and antipsychotics interact with these serotonin receptors to ultimately help people cope better with mental health conditions. For example, those suffering with depression are often prescribed SSRIs, or Selective Serotonin Reuptake Inhibitors. These drugs help relieve symptoms by boosting levels of serotonin in the brain and specifically increasing activity at the serotonin 1A receptor. This reduces brain activity in stress circuitry, which in turn helps one better handle their disease.
While activating this 1A receptor proves important and effective, these researchers say that activating the 2A pathway—responsible for creating the effect of psychedelics—may be therapeutically important as well. And in their paper, they argue the possibility of effectively treating certain mental illnesses with psychedelics. “Activating serotonin 2A receptors may be a good thing, as it makes individuals very sensitive to context and to their environment,” said Dr. Robin Carhart-Harris, lead author of the research paper and Head of Psychedelic Research at Imperial. “Crucially, if that is made therapeutic, then the combination can be very effective. This is how psychedelics work—they make people sensitive to context and open to change via activating the 2A receptor.”
Serotonin has proven to make situations less stressful, via activation of the 1A pathway. However, this might not always be enough, as is the basis of the researchers’ argument. They believe that in certain cases, activating the 2A pathway is also necessary, as it helps patients alter negative behaviors and thought patterns. Furthermore, it just might put up a fight against certain brain wiring that has become resistant to change when conditions like obsessive compulsive disorder (OCD) and addiction are present.
According to the authors of the study, the introduction of the two-pronged model could lead to a notable shift in psychiatric care. It has the potential to offer patients who endure their mental illnesses with pharmaceuticals a secondary treatment option, which is to actively address it instead by fundamentally modifying behaviors and thinking. Furthermore, Dr. Carhart-Harris believes that this new model sheds light on the important role that environment plays in drug administration, asserting that drugs—at least psychedelics and possibly SSRIs—should not be administered in isolation. “We need to pay more attention to the context in which medications are given. We have to acknowledge the evidence which shows that environment is a critical component of how our biology is expressed,” he said.
*This research paper “Serotonin and brain function: a tale of two receptors” by Robin Carhart-Harris and David Nutt is published in the Journal of Psychopharmacology.*