Presynaptic dopamine function measured with [¹⁸F]fluorodopa and L-DOPA effects on impulsive choice

Area of Science:

• Neuroscience
• Psychopharmacology

Background:

• Previous research suggested L-DOPA's effects on decision-making follow an inverted U-shaped curve.
• Both low and high dopamine signaling extremes were linked to increased impulsivity.

Purpose of the Study:

• To investigate the relationship between presynaptic dopaminergic function and impulsivity.
• To test the hypothesis of an inverted U-shaped dopamine function in reward-based decision-making.

Main Methods:

• Positron emission tomography ([18F]DOPA PET) was used to measure dopaminergic function.
• Effective distribution volume ratio (EDVR) assessed [18F]DOPA influx and [18F]dopamine washout rates.
• Participants' impulsivity and delay discounting were measured.

Main Results:

• Higher baseline EDVR (dopaminergic function) correlated with lower self-reported impulsivity.
• Individuals with higher baseline EDVR became more impulsive after L-DOPA.
• Individuals with lower baseline EDVR showed reduced impulsivity after L-DOPA.

Conclusions:

• Striatal dopaminergic activity is related to trait impulsivity.
• A non-linear, inverted U-shaped relationship exists between dopaminergic function and delay discounting.
• Individual differences in dopamine signaling impact responses to L-DOPA, affecting impulsive choice.