Subanesthetic dose of ketamine decreases prefrontal theta cordance in healthy
volunteers: implications for antidepressant effect.
Author(s): Horacek J, Brunovsky M, Novak T, Tislerova B, Palenicek T, Bubenikova-Valesova V,
Spaniel F, Koprivova J, Mohr P, Balikova M, Hoschl C.
Affiliation(s): Prague Psychiatric Centre, Prague, Czech Republic. horacek@pcp.lf3.cuni.cz
Publication date & source: 2010, Psychol Med. , 40(9):1443-51
BACKGROUND: Theta cordance is a novel quantitative electroencephalography (QEEG)
measure that correlates with cerebral perfusion. A series of clinical studies has
demonstrated that the prefrontal theta cordance value decreases after 1 week of
treatment in responders to antidepressants and that this effect precedes clinical
improvement. Ketamine, a non-competitive antagonist of N-methyl-D-aspartate
(NMDA) receptors, has a unique rapid antidepressant effect but its influence on
theta cordance is unknown.
METHOD: In a double-blind, cross-over, placebo-controlled experiment we studied
the acute effect of ketamine (0.54 mg/kg within 30 min) on theta cordance in a
group of 20 healthy volunteers.
RESULTS: Ketamine infusion induced a decrease in prefrontal theta cordance and an
increase in the central region theta cordance after 10 and 30 min. The change in
prefrontal theta cordance correlated with ketamine and norketamine blood levels
after 10 min of ketamine infusion.
CONCLUSIONS: Our data indicate that ketamine infusion immediately induces changes
similar to those that monoamineric-based antidepressants induce gradually. The
reduction in theta cordance could be a marker and a predictor of the fast-acting
antidepressant effect of ketamine, a hypothesis that could be tested in
depressive patients treated with ketamine.
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