Metaphor Can Help Patients Understand Receptor Modulation for Antidepressant Medications

Being a bit of a psychopharmacology nerd, I get excited when we are given access to new and interesting mechanisms of action when newer classes of medication come to market. Regardless of the specifics, novel mechanisms of action may provide different pharmacologic approaches that may hold the hope of offering improvement to patients who have failed to adequately respond to medications that work on more traditional mechanisms of action. 

That is not to suggest that novel mechanisms of action are necessarily superior to the mechanisms of older medications. The only way to determine which mechanism is more effective is through a series of carefully designed studies comparing them. 

However, I do feel comfortable saying that access to an armamentarium of antidepressant medications with widely varying mechanisms of action is likely a benefit. Different isn’t necessarily better, but it is different.  

When I speak to colleagues and patients about the ways in which different mechanisms of action work, I frequently rely on metaphor as a useful tool to help explain complex concepts. In discussing the differences between the various mechanisms of action of antidepressants, I use the metaphor of a factory filled with machines that can be turned on or off. With our older monoamine oxidase inhibitors (MAOIs) we prevent the catabolism of various, non-specific monoamines, so the metaphor in the factory is having an unskilled workforce and pushing back the age of retirement to prevent them from stopping their work.

For the tricyclics, serotonin reuptake inhibitors, serotonin/norepinephrine reuptake inhibitors, and norepinephrine/dopamine reuptake inhibitors, the metaphor I use is that we are locking the exit doors at the factory, so we are putting our unskilled workforce on overtime, keeping them at work longer, continuing their unskilled work. 

I describe these meds as “unskilled” workers not to be pejorative, but rather to point out that in using a medication that inhibits degradation or blocks reuptake, we are keeping the agonist present at higher concentrations. In doing so, we are stimulating all of the subtypes of the receptors for that particular neurotransmitter, regardless if that is what we would really prefer to do. These medications are “unskilled” because the only thing they can do is to turn all the machines (receptors) “on”, and we are left playing an odds game. In other words, we are basically saying: 

“Well, I am most interested in turning on receptor #1, but I don’t really want to turn on receptors #2 and #3, and I am ambivalent about receptor #4. Unfortunately, I can only tell my unskilled workers to go in and turn everything on, so I guess turning on the others is just the cost of doing business.” 

In other words, using unskilled workers potentially creates some “collateral damage,” creating other effects that you may or may not want to occur. 

However, in using receptor modulation as a mechanism of action, you may have the possibility of hiring a set of “highly-skilled” workers. Instead of managing your factory purely by deciding the number of unskilled workers you want turning everything in sight “on”, you are bringing in consultants that have the ability to turn certain machines “on” and other machines “off”. If your medication has partial agonist properties, you may have a “highly-skilled consultant” that can install an automatic thermostat on a certain machine that can allow it to be turned up or down depending on the environment in which that machine is operating. 

I have found this metaphor useful to our colleagues in training, our colleagues in practice, and to patients and families in helping them understand and visualize the ways in which different medications work. 

Do you use similar metaphors in explaining how various medications work to your patients, and, if so, do you think it is beneficial?

Chris Bojrab, MD, is the president of Indiana Health Group, the largest multidisciplinary behavioral health private practice in Indiana, established in 1987. He is a board certified psychiatrist and a Distinguished Fellow of the American Psychiatric Association who treats child, adolescent, adult, and geriatric patients. His areas of interest include psychopharmacology, sleep disorders, and gambling addiction. For more information and disclosures, visit  www.chrisbojrabmd.com

The views expressed on this blog are solely those of the blog post author and do not necessarily reflect the views of Psych Congress Network or other Psych Congress Network authors.