Augmented tendency to act and altered impulse control in alcohol use disorders

Area of Science:

• Neuroscience
• Motor Control
• Addiction Research

Background:

• Action preparation involves modulating corticospinal tract excitability through excitatory and inhibitory processes.
• Impaired motor control processes may contribute to problematic alcohol consumption.
• Understanding these mechanisms in heavy drinkers and those with severe alcohol use disorder is crucial.

Purpose of the Study:

• To evaluate motor system excitatory and inhibitory processes in non-treatment seeking heavy drinkers (HDs) and inpatients with severe alcohol use disorder (SAUDs).
• To assess the impact of alcohol-related cue exposure on these motor processes.
• To investigate the neural correlates of action preparation in alcohol use disorder.

Main Methods:

• Utilized a choice reaction time task with single-pulse transcranial magnetic stimulation (TMS) over the primary motor cortex.
• Measured motor-evoked potentials in hand muscles to probe excitatory and inhibitory influences.
• Compared 15 healthy controls (HCs), 15 HDs, and 15 SAUDs, with and without virtual reality alcohol-related environmental exposure.

Main Results:

• Both HDs and SAUDs exhibited significantly higher excitatory influences, particularly in the dominant hand, compared to HCs.
• SAUDs showed deficient inhibitory influences, while HDs had normal inhibitory control.
• Alcohol-related exposure increased craving in HDs but did not alter motor control processes.

Conclusions:

• Enhanced excitatory processes may characterize hazardous drinking and alcohol use disorder.
• Deficient impulse control, indicated by reduced inhibitory processes, is specific to severe alcohol use disorder and may result from chronic neurotoxicity.
• Abnormally strong action tendencies could drive excessive alcohol consumption, while impaired impulse control marks severe AUD.