Neuromodulation of delay discounting, the reflection effect, and cigarette consumption

Area of Science:

• Neuroscience
• Addiction Research
• Cognitive Psychology

Background:

• Smokers and substance users exhibit steeper delay discounting, correlating with relapse and poor treatment outcomes.
• The left dorsolateral prefrontal cortex (DLPFC) regulates impulsive choices; increased DLPFC activity is linked to lower discounting rates.

Purpose of the Study:

• To investigate if high frequency repetitive transcranial magnetic stimulation (HF rTMS) over the left DLPFC can decrease delay discounting and impulsive decision-making in smokers.
• To assess the effect of HF rTMS on cigarette consumption.

Main Methods:

• A single-blind, within-subjects design involving 47 smokers and 19 non-smokers.
• Participants underwent three counterbalanced sessions of HF rTMS (20 Hz, 10 Hz, sham) targeting the left DLPFC.
• Delay discounting, gambling task performance, and cigarette consumption were measured at baseline and post-stimulation.

Main Results:

• HF rTMS significantly decreased delay discounting for monetary gains (p < .01).
• Conversely, HF rTMS increased delay discounting for monetary losses (p < .01), creating a reflection effect.
• No significant effect of HF rTMS was observed on cigarette consumption.

Conclusions:

• Left DLPFC stimulation with HF rTMS influences delay discounting, but differentially for gains versus losses.
• The findings suggest HF rTMS alone is insufficient to reduce cigarette consumption.
• Combined HF rTMS with cognitive-behavioral interventions may enhance treatment efficacy for substance dependence.