Despite the risk, smoking has only slightly decreased and the percenta
ge of heavy smokers increases. The reason for the paradoxical situatio
n has now been identified in more than 95 % of the cases and is due to
behaviour amplified by a pharmacological dependence on nicotine. The
psyche-active effects of nicotine binding to nicotine receptors in the
brain, produce a quasi constant physical dependence and a psychic dep
endence in certain smokers.