It is important to use an integrated set of features to establish treatment response biomarkers that reflect the pathophysiology of depression. A recent study determined the relationship between regional brain activity at rest and blood metabolites associated with treatment response to escitalopram to determine the attributes of depression that respond to treatment.

It measured the Blood metabolite levels and resting-state brain activity in patients with moderate to severe depression (n = 65) before and after 6–8 weeks of escitalopram treatment. It further compared the treatment between Responders and Non-responders; and also examined the relationship between blood metabolites and brain activity concerning treatment responsiveness in patients and healthy controls (n = 36).

The study found a clinical response (>50% reduction in the Hamilton Rating Scale for Depression score) in 49.2% of the patients and classified them as Responders and the remaining as Nonresponders. It found lower levels of the pretreatment fractional amplitude of low-frequency fluctuation (fALFF) value of the left dorsolateral prefrontal cortex (DLPFC) and plasma kynurenine levels in Responders, and their rate of increase after treatment correlated with an improvement in symptoms. Moreover, it found a significant correlation between the fALFF value of the left DLPFC and plasma kynurenine levels in pretreatment patients with depression and healthy controls.

The decreased resting-state regional activity of the left DLPFC and plasma kynurenine levels predicts treatment response to escitalopram. This also suggests its involvement in the pathophysiology of major depressive disorder in response to escitalopram treatment.

Psychiatry and Clinical Neurosciences. 2022;76(8) :367-376.https://doi.org/10.1111/pcn.13373