The idea of neuromarkers of psychiatric disorders has arrived with the first FDA-approved neuromarker for ADHD, which is a ratio of the relative power between two different brainwaves, theta and beta, in the cerebral cortex as measured by electroencephalography (EEG). It is called the theta-beta ratio [TBR], and it is a useful tool in supplementing the diagnosis of ADHD in about 25-40% of ADHD patients. Although the TBR is the first to be approved by the FDA, there are many other potential neuromarkers like it that we can measure using quantitative EEG, which may be able to help clinicians and patients to better understand their psychiatric symptoms, and even may help determine the best treatment.
Controversy over the meaning and use of neuromarkers remains. These measures should change with treatment only if they are causative for the condition or symptom(s); if they are not causative but are correlative, they may or may not change with changes in symptoms. Another possibility is that they may represent an underlying risk for the condition or symptom, but may not be sufficient to cause the condition or symptom, which, again, would not necessarily result in changes to the measure when symptoms change. This is similar to the mechanism of genetics and how individual genetic variations may correlate with diseases or indicate increased risk of disease, but the genetic variation in and of itself is insufficient to cause the disease. The current data suggests that a similar mechanism is likely for at least some of these neuromarkers, which makes sense for the complex nature of mental health.
Despite the caveats, the emerging field of neuromarkers for mental health disorders is very exciting! For the first time, we may have objective measures for mental health that can support psychological diagnoses, prognoses, as well as the possibility for monitoring treatment efficacy. We will soon have the capability to measure and explore these potential neuromarkers at Rose City Therapeutics since we now have been trained and have purchased the equipment – it is on its way!