Whether it is "only" a cigarette a day or every now and then, whether it is an electronic cigarette or passive smoking, the message that comes from more and more scientific studies is that smoking or breathing smoke, in all its forms, hurts and the damage goes well beyond what we commonly believe. Today we know that nicotine, contained in cigarette smoke, can even act on the brain, blocking the production of some hormones with possible repercussions on behavior and the female reproductive system. This emerges from a very recent scientific research presented by a team of Swedish scientists from the University of Uppsala at the European College of Neuropsychopharmacology annual congress, held in Vienna between 15 and 18 October 2022 (Comasco et al, 35th ECNP Congress, 15-18 Oct 2022, Vienna).
Nicotine blocks estrogen in the brain, the study
Scientists conducted a very small study by recruiting 10 volunteers. Study participants were asked to inhale a dose of nicotine equivalent to that contained in a cigarette. Later, the volunteers underwent medical tests, such as MRI and PET. Well, what emerged was that the inhaled nicotine was enough to block estrogen production in the female brain. In fact, estrogen is not only produced by the ovaries, which still remain the main source, but also by other organs, including the brain.
Cerebral estrogen blockade, what are the consequences?
What implications does this have? All the possible effects of cerebral estrogen blockade are not yet known and need to be evaluated in subsequent studies. But it is possible to hypothesize important consequences based on some considerations. The first is that estrogen in the brain is a true elixir of youth. In fact, as shown by an American study performed by scientists from Northwestern Medicine University and presented a few years ago at the 2010 Neuroscience congress held in San Diego, estrogen stimulates the connection between neurons, improves brain function and memory (Srivastava et al, Neuroscience 2010 in San Diego). Then, nicotine is an addictive substance and that is why it is found, as well as in cigarettes, also in electronic ones. Not only that, nicotine is also present in secondhand smoke. Finally, estrogens are not only the prerogative of women but are also present in men, albeit in lower quantities.
As mentioned, the study just presented is very small and much will still have to be done to shed light on all the aspects that remain in the shadows, for example if these results also apply to the male brain and what are the consequences that a blockage of brain estrogens may have on the reproductive system, brain function and behavior. But surely, what we have seen so far and the results of previous studies on the importance of cerebral estrogen allows us to understand that the damage of cigarette smoke, in all its forms, is incalculable, with consequences also on other organs as well as on the lungs. And the problem, as we have seen, is not only the production of carcinogenic substances, which electronic cigarettes aim to reduce, but also the presence of nicotine which acts on the brain by modifying its processes and functionality.