Spontaneous eye blink rate and dopamine synthesis capacity: Preliminary evidence for an absence of positive correlation

Abstract

Dopamine is central to a number of cognitive functions and brain disorders. Given the cost of neurochemical imaging in humans, behavioral proxy measures of dopamine have gained in popularity in the past decade, such as spontaneous eye blink rate (sEBR). Increased sEBR is commonly associated with increased dopamine function based on pharmacological evidence and patient studies. Yet, this hypothesis has not been validated using in vivo measures of dopamine function in humans. In order to fill this gap, we measured sEBR and striatal dopamine synthesis capacity using [ 18 F]DOPA PET in 20 participants (9 healthy individuals and 11 pathological gamblers). Our results, based on frequentist and Bayesian statistics, as well as region-of-interest and voxel-wise analyses, argue against a positive relationship between sEBR and striatal dopamine synthesis capacity. They show that, if anything, the evidence is in favor of a negative relationship. These results, which complement findings from a recent study that failed to observe a relationship between sEBR and dopamine D2 receptor availability, suggest that caution and nuance are warranted when interpreting sEBR in terms of a proxy measure of striatal dopamine.

A potential link between gambling addiction severity and central dopamine levels – evidence from spontaneous eye blink rates in gamblers and controls

“…First, the assumption of a positive correlation between sEBR and dopamine levels in striatum in humans is still under debate. In a recent preprint, Sescousse et al, (2017) found a negative relation between sEBR and dopamine synthesis capacity as assessed with [ 18F]DOPA PET in a mixed sample of gamblers and control participants. Dang et al (2017) found no significant correlation between D2/3 receptor availability and sEBR in humans.…”

“…However, in pathological gamblers, striatal D2/3-receptor availability was associated with mood related impulsivity and gambling severity (Clark et al, 2012;Boileau et al, 2013). In addition, van Holst et al (2017) found increased striatal dopamine synthesis capacity, as assessed with [ 18 F]fluoro-levodihydroxyphenylalanine ([ 18 F]DOPA) PET, in gamblers compared with controls.…”

“…Noteworthy, their subject sample was quite heterogeneous regarding age and body weight, and between 3 and 32 months separated subjects' sEBR assessment from PET imaging. In a preprint, Sescousse et al (2017) report a negative correlation between sEBR and striatal dopamine synthesis capacity in a mixed sample of healthy controls and gamblers. Thus, the association between sEBR and striatal dopamine still needs further consideration.…”