Effect of Ethanol on Brain Electrical Tissue Conductivity in Social Drinkers.

BACKGROUND

How the biophysics of electrical conductivity measures relate to brain activity is poorly understood. The sedative, ethanol, reduces metabolic activity but its impact on brain electrical conductivity is unknown.

PURPOSE: To investigate whether ethanol reduces brain electrical tissue conductivity.

STUDY TYPE: Prospective.

SUBJECTS: Fifty-two healthy volunteers (aged 18-37 years, 22 females, 30 males).

FIELD STRENGTH/SEQUENCE: 3 T, T1-weighted, multi-shot, turbo-field echo (TFE); 3D balanced fast-field echo (bFFE).

ASSESSMENT: Brain gray and white matter tissue conductivity measured with phase-based magnetic resonance electrical properties tomography (MREPT) compared before and 20 minutes after ethanol consumption (0.7 g/kg body weight). Differential conductivity whole brain maps were generated for three subgroups: those with strong ( ∆ σ max  > 0.1 S/m; N = 33), weak (0.02 S/m ≤  ∆ σ max  ≤ 0.1 S/m; N = 9) conductivity decrease, and no significant response ( ∆ σ max  < 0.02 S/m, N = 10). Maps were compared in the strong response group where breath alcohol rose between scans, vs. those where it fell.

STATISTICAL TESTS: Average breath alcohol levels were compared to the differential conductivity maps using linear regression. T-maps were generated (threshold P < 0.05 and P < 0.001; minimum cluster 48 mm3). Differential conductivity maps were compared with ANOVA.

RESULTS

Whole-group analysis showed decreased conductivity that did not survive statistical thresholding. Strong responders (N = 33) showed a consistent pattern of significantly decreased conductivity ( ∆ σ max  > 0.1 S/m) in frontal/occipital and cerebellar white matter. The weak response group (N = 9) showed a similar pattern of conductivity decrease (0.02 S/m ≤  ∆ σ max  ≤ 0.1 S/m). There was no significant relationship with breath alcohol levels, alcohol use, age, ethnicity, or sex. The strong responders' regional response was different between ascending (N = 12) or descending (N = 20) alcohol during the scan.

DATA

CONCLUSION

Ethanol reduces brain tissue conductivity in a participant-dependent and spatially dependent fashion.

EVIDENCE LEVEL: 1 TECHNICAL EFFICACY: Stage 2.