In a study done at Sahlgrenska Academy on nicotine withdrawal using rats, the first period of nicotine abstinence progressed as expected. After three months, the scientists were however surprised to see the lab rats suddenly become fearless and seek out well-lighted areas that are normally avoid by prey animals. Signaling in the brain’s reward system changed at the same time.
Julia Morud Lekholm, a researcher in addiction biology at the Institute of Neuroscience and Physiology, noted that this behavior indicates long lasting changes caused by nicotine that had not previously been identified. The nicotine appears to create a series of effects that gets worse over time.
To make sure that the unexpected results were not an isolated case, the researchers repeated the experiment another two times. 108 Animals were tested in total over a three-week period, of which 54 received nicotine and the rest a salt solution. The results were the same every time.
Morud Lekholm explained that the animals treated with nicotine spend much more time in the areas that are more frightening, when compared to those that only received salt solution injections. This behavior does not occur directly following the nicotine treatment, but only appears after three months or more into abstinence. She finds it very strange that animals that have not received any nicotine for three months suddenly demonstrate an increased spontaneous impulsiveness.
She added that it’s interesting that at the same time, changes become noticeable in the GABAergic system in the brain. This system normally slows the brain’s signaling. The GABA system in the studied region of the rats’ brains after another four months was so strongly affected, that its effects had been completely reversed. Instead of slowing the nerve cell signaling, it was being increased. If people had been involved, this would translate into an extensive risk of relapsing into smoking.
Although rats and people are very different, Morud Lekholm notes that in terms of the type of brain circuit that was studied, the brain’s reward system, humans and rats are very much alike. It is also possible to translate the results to humans to some extent, especially in terms of risk taking behavior. Not having good impulse control isn’t good for life in general, as this could lead to many bad situations that may have effects on the consumption of other drugs later in life.
Morud Lekholm believes the changed signaling in the brain explains to some extent part of the long lasting problems and difficulties experienced by many who want to quit smoking, or stop using tobacco, even though the time aspects of the study are not directly transferable to humans
Morud Lekholm understands that this is a life long struggle. This can be clearly seen in animals who, after such a long abstinence from nicotine, still have many changes in their reward system. She believes that more effort should therefore be made on this kind of research, to try to find new therapies, as it’s extremely difficult for people to be able to withstand the urge for longer periods.