Effect of Nicotine on Cognitive Performance in Non-smokers in a Nigerian University Community
The effects of nicotine on cognition are still elusive. The aim of the present study is to determine how exposure to nicotine affects specific cognitive domains in a random population of non-smokers in the age range 18-35 years. Ninety-nine non-smokers (80 males and 19 females), with no clinically classified blood pressure (≥140/90 or ≤ 90/60 mmHg), body mass index (≥ 25 kg/m2) or depression level score participated in the study. Nicotine was administered via chewing 4 mg nicotine gum for 15 minutes (one-chew/3seconds). The cognitive domains used in this study, the neuropsychometric test instruments and the predetermined reaction time respectively include global cognitive function (mini-mental state examination MMSE), working memory (Two-back task, reaction time: 1 sec.) and verbal information processing (Logical reasoning task, reaction time: 4 sec.). Performance scores (PS) on cognitive tasks, before (baseline) and after administration of nicotine were analyzed using paired student’s-test (P < 0.05). Correlations between baseline PS and magnitudes of nicotine effect were determined using Pearson product moment correlation (r). PS and the magnitudes of nicotine effect compared across 3-subgroups based on baseline PS using one-way ANOVA. The results showed that nicotine significantly improved PS on all the cognitive tasks but the magnitudes of the improvements increased significantly with decrease in baseline PS. The assessment of the cognitive effect of nicotine may be misleading if based exclusively on neuropsychological test scores without correlations with baseline PS. Indication for baseline dependency effect of nicotine is considered.
Keywords: Cognitive domain; Nicotine-gum; Mini-mental state examination; Two-back task; Logical reasoning task; Reaction time; Performance scores.