Does nicotine improve attention? Effects of a single administration of low-dose nicotine on cognitive performance of non-nicotine users

Abstract

We investigated the effects of low-dose nicotine on pupil size, eye blink rates (EBR), and visual attention amongst non-nicotine users while performing a multiple-object-tracking (MOT) task. Participants were tested with a double-blind, 2 (Drug: placebo vs. 2 mg nicotine) x 3 (Load: two vs. three vs. four) design. The drug manipulation was administered with chewing gums and divided into two sessions that were counterbalanced across participants with at least 72 hours in between the sessions. In the MOT task, participants were asked to track either two, three, or four circles out of 12 circles in motion. At the end of each trial, participants indicated whether a highlighted circle was one of the targets or not. Pupils and eye movement were recorded binocularly during the MOT task using the SMI RED500 eye tracker at a 60-Hz sample rate. Results revealed that pupils were relatively smaller in the nicotine than in the placebo condition. Pupil dilation increased proportionally to the target load. In contrast, EBR declined as the target load was higher. Response accuracy was higher in the small target load than in the medium and high target loads. Effects of nicotine and target load on response latency were not observed. We concluded that a small dose of nicotine was sufficient to constrict pupil size through its interaction with acetylcholine in the parasympathetic nervous system. However, a small dose of nicotine might not have a direct effect on dopaminergic system to stimulate eye blinks, enhance attention, and speed behavioural response.