Alcohol affects the brain's resting-state network in social drinkers

PLoS One. 2012;7(10):e48641. doi: 10.1371/journal.pone.0048641. Epub 2012 Oct 31.

Abstract

Acute alcohol intake is known to enhance inhibition through facilitation of GABA(A) receptors, which are present in 40% of the synapses all over the brain. Evidence suggests that enhanced GABAergic transmission leads to increased large-scale brain connectivity. Our hypothesis is that acute alcohol intake would increase the functional connectivity of the human brain resting-state network (RSN). To test our hypothesis, electroencephalographic (EEG) measurements were recorded from healthy social drinkers at rest, during eyes-open and eyes-closed sessions, after administering to them an alcoholic beverage or placebo respectively. Salivary alcohol and cortisol served to measure the inebriation and stress levels. By calculating Magnitude Square Coherence (MSC) on standardized Low Resolution Electromagnetic Tomography (sLORETA) solutions, we formed cortical networks over several frequency bands, which were then analyzed in the context of functional connectivity and graph theory. MSC was increased (p<0.05, corrected with False Discovery Rate, FDR corrected) in alpha, beta (eyes-open) and theta bands (eyes-closed) following acute alcohol intake. Graph parameters were accordingly altered in these bands quantifying the effect of alcohol on the structure of brain networks; global efficiency and density were higher and path length was lower during alcohol (vs. placebo, p<0.05). Salivary alcohol concentration was positively correlated with the density of the network in beta band. The degree of specific nodes was elevated following alcohol (vs. placebo). Our findings support the hypothesis that short-term inebriation considerably increases large-scale connectivity in the RSN. The increased baseline functional connectivity can -at least partially- be attributed to the alcohol-induced disruption of the delicate balance between inhibitory and excitatory neurotransmission in favor of inhibitory influences. Thus, it is suggested that short-term inebriation is associated, as expected, to increased GABA transmission and functional connectivity, while long-term alcohol consumption may be linked to exactly the opposite effect.

Publication types

  • Controlled Clinical Trial

MeSH terms

  • Adult
  • Alcohol Drinking*
  • Algorithms
  • Brain / physiology*
  • Brain Mapping
  • Double-Blind Method
  • Electroencephalography
  • Ethanol / analysis
  • Female
  • Humans
  • Hydrocortisone / analysis
  • Male
  • Models, Neurological
  • Nerve Net / physiology*
  • Neural Inhibition / physiology
  • Rest / physiology*
  • Saliva / chemistry
  • Social Environment
  • Synaptic Transmission / physiology
  • Young Adult

Substances

  • Ethanol
  • Hydrocortisone

Grants and funding

This work has been partially funded by the Committee for Biomedical Research, Central Health Council of the Greek Ministry of Health and Social Solidarity (project 83785). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.