Effect of paroxetine and bupropion on human resting brain perfusion: an arterial spin labeling study

Due to the physiological coupling with metabolism, brain perfusion is a potential aid in understanding the effects of medication on neural activity in vivo. In this study, arterial spin labeling (ASL) was used to quantify the effect of seven days of administration of paroxetine (20 mg), bupropion (150 mg) on cerebral blood flow levels at rest in a double-blind, placebo-controlled crossover design in N=21 healthy participants. Paroxetine administration was associated with diffuse cortical perfusion decrements, more marked in the prefrontal region, and with decrements in the striatum, caudate and the basal forebrain. The effect of bupropion on the cortex was similar but less conspicuous. In the brainstem, there was suggestive evidence of perfusion decrements in the main serotonergic and noradrenergic nuclei. These results demonstrate the existence of effects on rest perfusion of antidepressant medication of potential use in monitoring its action. The observed perfusion reductions may be related to compensatory decrements of monoaminergic neural activity in the initial phases of treatment that are observed under both drugs following the increase in extracellular concentration of transmitters.