EVIDENCE FOR A CENTRAL CHOLINERGIC EFFECT OF HIGH-DOSE THIAMINE

In vitro animal studies have suggested that thiamine is involved in th e presynaptic release of acetylcholine. Total thiamine content in chol inergic nerve terminals is comparable with that of acetylcholine, and the phosphorylation state of thiamine changes with release of acetylch oline. Thiamine binds to nicotinic receptors and may exhibit anticholi nesterase activity. Based on these observations, we investigated the e ffects of pharmacological doses of thiamine on the cognitive deficits induced by the anticholinergic scopolamine in healthy young adults usi ng a randomized, double-blind, placebo-controlled, double-crossover de sign. Drug effects were assessed by P3 event-related potential, quanti tated electroencephalography, and free recall memory. Conditions inclu ded (1) baseline, (2) thiamine 5 gm p.o. and scopolamine 0.007 mg/kg I M, and (3) lactose PO and scopolamine 0.007 mg/kg IM. Thiamine signifi cantly reduced adverse effects of scopolamine on P3 latency, spectral components of electroencephalography, and memory recall. The results a re consistent with a cholinomimetic effect of thiamine in the central nervous system. Additional studies are needed to delineate the basic m echanisms and possible therapeutic efficacy of thiamine at pharmacolog ical dosages.