Smokers tend to have a thinner outer brain layer than non-smokers, new research suggests.
Scientists found that in people who have avoided smoking, the brain cortex - the layer which is important for thinking skills - is thicker than among smokers.
They cautiously suggest that the cortex might regain some thickness once smokers quit, but that this was not seen in all regions of the brain.
The study gathered health data and analysed MRI scans of 244 males and 260 females with an average age of 73, around half of whom were former or current smokers.
They analysed how a person's smoking habit was linked with the thickness of the brain's cortex using detailed MRI brain scans, careful image analysis and statistical models.