Smoking at an early age can cause attention deficits in later life. Researchers at the Neuroscience Campus Amsterdam (part of VU University and its medical centre) have discovered a new mechanism that explains how exposure to nicotine at an early age can lead to brain damage. The research was jointly funded by the Netherlands Organization for Scientific Research and was published as an advance online publication of the scientific journal Nature Neuroscience on Sunday 20 February.
The researchers exposed adolescent rats to nicotine for a limited period of time. When these rats were subsequently tested at an adult age, the exposure was shown to have decreased their ability to concentrate and to have increased their impulsivity. The nicotine therefore caused long-term damage: the rats demonstrated behavioral problems as adults. Rats who only received nicotine as adults, did not suffer from these lasting consequences. The study clearly shows that the adolescent brain is very vulnerable to addictive substances, such as nicotine. When translated to humans, this study indicates that smoking at an early age could lead to attention deficit problems in adulthood.
Sabine Spijker, Tommy Pattij and Huibert Mansvelder of the Neuroscience Campus Amsterdam discovered that the level of the protein metabotropic glutamate receptor 2 (mGluR2) decreased in pubescent rats after exposure to nicotine and that this protein also functioned less well in the prefrontal cortex, the part of the brain involved in cognitive functions, such as decision making and planning. The protein prevents overstimulation of nerve cells. However, the activity of the nicotine-damaged protein could be restored by administering drugs.
Smoking, and the intake of nicotine, is highly addictive and it often starts during adolescence. Recent studies had already shown that adolescents are more sensitive to nicotine activity and that smoking in this period affects the development of the front of the brain. Yet how nicotine caused such harmful long-term effects had not been clear up until now.
How nicotine causes problems in the human brain cannot be deduced from this study. A different type of research is needed for that in which study subjects are exposed to nicotine for short, specific periods of time. However such a study is difficult to reproduce in humans because people who start smoking as young adults usually continue smoking for the rest of their lives.
A large part of the research was carried out by the PhD students Danielle Counotte and Natalia Goriounova. NWO financed the multidisciplinary project that was realised at the CNCR (Center for Neurogenomics and Cognitive Research), which is part of VU University Amsterdam and its medical center.
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Lasting synaptic changes underlie attention deficits caused by nicotine exposure during adolescence. Danielle S. Counotte, Natalia A. Goriounova, Ka Wan Li, Maarten Loos, Roel C. van der Schors, Dustin Schetters, Anton N.M. Schoffelmeer, August B. Smit, Huibert D. Mansvelder, Tommy Pattij & Sabine Spijker. Nature Neuroscience - published online: 20 February 2011