The dangers of cigarette smoking are a constant
topic to which most of us nod wisely and switch off, whether we’re smokers or
non-smokers. The stress on cancer, heart disease and pulmonary problems
dominates. But we should remember that the ingestion of nicotine is an addiction
and that its affect on the brain is at least as relevant.
With a nod
in that direction, Yu et al have
stuffed three-quarters of a pack of heavy smokers into the big magnet (1). They
used a similar number of controls, of course. The “heavy” designation meant
that the chronic smokers smoked a pack of 20 each day and had been smoking for
at least 15 years.
The gray and white matter volumes were recorded for
the various regions of the brain. The heavy smokers had less in the cerebellum
but more in their putamen. The blood flow in the cerebellum of each heavy
smoker increased after smoking indicating an increase in activity.
Remember that the gray matter is made up of the
neurons with the axons or tails which transmit the signals being the white
matter. So a smaller volume wouldn’t seem to be a good thing. The cerebellum is
associated with your motor control, so smoking to help you concentrate on that
fine painting or assembly task puts you in an interesting quandary. The stimulated
activity indicated by the blood flow looks good, but overall the progressive
volume reduction may be a high price.
The putamen has high dopamine (a pleasurable
hormone) content and a larger amount of material here may make you grin a
little more. This region also seems to be involved with your dislike of people
and the way you react to them so you might end up smiling for a few minutes
before returning to your usual grouchy, hard-bitten personae. Ah, time for another
cigarette!
