Psychiatric neuroscience helps us to understand the distal mechanism of action of the medications we use in psychiatry. While the proximal mechanism of most antidepressants may be to increase synaptic levels of serotonin, we now know that we cannot extrapolate backwards to say that depression is caused by insufficient levels of serotonin. By eschewing the reductionist model of psychiatric disorder etiology, we have instead chosen to take a holistic biopsychosocial perspective that investigates and understands the many different pathways to mental illness, from genetics to gestational exposures, from abnormal brain development to childhood experiences, from relationship dynamics to conditioned patterns of maladaptive thinking and behavior. Despite adopting this wide perspective that takes into account the plethora of influences that can cause a psychiatric disorder to develop, what is important to understand from the neuroscience is that the final result for individuals with any psychiatric disorder is that there are changes in the connectivity and function of various brain circuits that correlate with the symptoms of their respective illness.
Antidepressants can help partially correct the neural network imbalances of unipolar depression via different proximal mechanisms but with the same final result. In depressed individuals, these beneficial changes in neural network activity have been shown to occur secondary to drugs that have different mechanisms of action, such as increasing synaptic serotonin, increasing synaptic norepinephrine or dopamine, inhibiting an adrenergic receptor, or blocking a glutamate receptor. We are learning more and more about what changes in neural network activity can occur with each of the myriad pharmacological mechanisms of action, and which symptom domains are most likely to be impacted.
Here at Mind Therapy Clinic, we stay abreast of all the latest developments in psychopharmacology. So when new psychiatric medications become available, we are quick to understand what makes the medications different from those that are already available. Fortunately, psychiatric medication R & D has been going through a renaissance of sorts. After a few decades where every new medication the FDA approved had the same exact mechanism of action as those already available, the past decade has seen progress in the development of drugs with novel mechanisms of action, such as drugs targeting certain serotonin or dopamine receptors, drugs that act on neuropeptide receptor targets, drugs that partially activate and partially block a given receptor (to varying degrees), and drugs that will work for a month or more after a single intramuscular injection, to name a few.
Several pharmaceutical companies are currently working on the development of drugs that act on glutamate receptors, a whole new class of receptor targets previously untargeted but critically important for brain function and emotional regulation. There has also been explosive interest in the extremely powerful and rapid-acting antidepressant effects of ketamine, an old drug that blocks a glutamate receptor called NMDA that is critical for the mechanisms of neural plasticity (LTP and LTD). Coupling pharmacological treatments with specific psychotherapy methods that are known to alter neural plasticity in similar or complementary ways can produce synergistic benefits leading to more robust recovery than either method alone, and the clinicians at Mind Therapy Clinic use this science to guide our treatment approach with patients.