The combined effect of alcohol and temazepam on information processing

The present research investigated the separate and interactive effects of high doses of a minor tranquilliser (temazepam) (20 mg) and alcohol (BAC = 0.10%) on human information processing using a dual-task paradigm. For this purpose dual task methodology was combined with P300 amplitude and latency as an index of resource allocation. A dual task paradigm in which subjects were instructed to attend to two tasks concurrently (which had the effect of increasing overall cognitive load) was used to indicate if the affects of alcohol and/or temazepam impaired the contextual updating of neuronal models in the brain and/or reduced specific 'pools of available resources'. Twelve subjects completed four drug treatments in a repeated measures design. The four drug treatments organised in a two by two design, included a placebo condition (alcohol no/temazepam no), an alcohol only condition (alcohol yes/temazepam no), a temazepam only condition (alcohol no/temazepam yes), and a combined condition (alcohol yes/temazepam yes). Event-related potentials were recorded from midline sites Fz, Cz and Pz within a dual task paradigm. The results indicated that at higher doses, widespread neural depression by alcohol overlapped the specific depressant effects of temazepam. The effect of ingesting high doses of alcohol and temazepam was synergistic, that is the combined effects of alcohol and temazepam were greater than their summated individual effects. In terms of information processing, from the perspective of contextual updating the process of updating the pre-existing neuronal model may be restricted, or from the view of resource allocation the actual pool of available resources may have been reduced. The RT data suggested that alcohol and temazepam may have had an additive effect on psychomotor processing. Both alcohol and temazepam significantly increased RT when ingested separately, but there was no interaction between the two drugs. Therefore alcohol and temazepam appeared to affect different aspects of RT processing.