在很多年前，儿童被告诫不要吸烟，因为吸烟可以阻碍长身体，而如今刊登在国际杂志Molecular Psychiatry上的一篇研究论文中，来自麦基尔大学等处的研究人员通过研究表明，长期吸烟或可影响个体的大脑皮层，使得大脑皮层变薄;大脑皮层是个体大脑的外层结构，其对于个体的认知功能非常关键，比如对记忆力、语言能力以及感知能力都很关键，有意思的是，本文研究发现，停止吸烟或可帮助恢复部分大脑皮层的厚度。

        文章中，研究者对244名男性和260名女性个体进行研究，本次研究规模是此前进行吸烟和皮质厚度相关连研究规模的5倍以上;参与者的平均年龄为73，研究对象包括当前吸烟者、戒烟者以及不吸烟者;所有受试者都在1947年作为儿童的时候参与了苏格兰的一项心理调查。研究者利用对受试者近期个人访谈中获得的健康数据进行分析，同时也对个体的MRI数据进行研究来解释当前个体大脑皮层的状态。

        研究者Sherif Karama教授说道，我们发现相比不吸烟者而言，年龄为73岁的吸烟者和戒烟者大脑皮层中的很多区域都比前者薄，而停止吸烟的个体似乎也会慢慢恢复其大脑皮层的厚度，但这种恢复过程非常缓慢，但并不全面;本文研究中研究者对较重的戒烟者在戒烟25年后进行观察，发现其大脑皮层仍然较薄。

        尽管大脑皮层会随着机体正常老化而慢慢变薄，但本文研究发现吸烟可以加速大脑皮层的变薄速度，而较薄的大脑皮层往往和成年人认知能力下降直接相关;最后研究者Karama说道，我们应该告知吸烟者烟草可以加速其大脑皮层变薄的速度，从而引发认知能力退化，而且在个人停止吸烟很多年后其大脑皮层变薄依然会不断持续。

        doi:10.1038/mp.2014.187

        PMC:

        PMID:

Cigarette smoking and thinning of the brain’s cortex

        S Karama1,2, S Ducharme1,3,4,5, J Corley6, F Chouinard-Decorte1, J M Starr7,8, J M Wardlaw7,9,10, M E Bastin7,9,10 and I J Deary6,7

        Cigarette smoking is associated with cognitive decline and dementia, but the extent of the association between smoking and structural brain changes remains unclear. Importantly, it is unknown whether smoking-related brain changes are reversible after smoking cessation. We analyzed data on 504 subjects with recall of lifetime smoking data and a structural brain magnetic resonance imaging at age 73 years from which measures of cortical thickness were extracted. Multiple regression analyses were performed controlling for gender and exact age at scanning. To determine dose–response relationships, the association between smoking pack-years and cortical thickness was tested and then repeated, while controlling for a comprehensive list of covariates including, among others, cognitive ability before starting smoking. Further, we tested associations between cortical thickness and number of years since last cigarette, while controlling for lifetime smoking. There was a diffuse dose-dependent negative association between smoking and cortical thickness. Some negative dose-dependent cortical associations persisted after controlling for all covariates. Accounting for total amount of lifetime smoking, the cortex of subjects who stopped smoking seems to have partially recovered for each year without smoking. However, it took ~25 years for complete cortical recovery in affected areas for those at the mean pack-years value in this sample. As the cortex thins with normal aging, our data suggest that smoking is associated with diffuse accelerated cortical thinning, a biomarker of cognitive decline in adults. Although partial recovery appears possible, it can be a long process.