Deficits in peripheric and central olfactory measurements in smokers: evaluated by cranial MRI

Cigarette smoking remains a serious health problem all over the world. We investigated the peripheral and central olfactory pathways in young male smokers to determine whether there is a relationship between the amount of cigarettes smoked and duration of smoking and the dimensions of the olfactory areas.

In this retrospective study, cranial Magnetic Resonance Imaging (MRI) images of adult male smokers aged ≤ 40 years (n = 51) and 50 healthy male adults were analyzed. The olfactory bulbus (OB) volumes and olfactory sulcus (OS) depths, insular gyrus, and corpus amygdala areas were measured via cranial MRI. In the smoker group, the number of cigarettes smoked and duration of smoking were noted and the Brinkmann index was calculated.

OB volume, OS depth, and the insular gyrus areas of the smokers were lower than in the control group (p < 0.05). There were no differences between the groups in terms of the corpus amygdala measurements (p > 0.05). No significant correlations were found between the number of cigarettes smoked daily, smoking duration, and the Brinkmann index and the peripheral and central olfactory measurements in our study (p > 0.05).

In smokers, OB volumes, the OS, and the central areas decrease bilaterally, regardless of smoking duration and number of cigarettes smoked daily. This could be related to inflammatory mediators that may be harmful to the olfactory neuroepithelium, gray matter atrophy in the brain, or endothelial damage related to smoking and its effects on blood support to the brain and olfactory regions.