From Nicotine science and policy Q & A by Clive Bates

No, this is a scare story and the claims do not bear scrutiny. Some public figures, including the US Surgeon General, have suggested that nicotine damages the adolescent brain. The evidence for this hypothesis comes only from a few rodent studies. These are an unreliable guide to human risk because the rodent brain does not offer a reliable proxy for the human brain and it is difficult to design experiments that are controlled to give a mouse equivalent exposure to a human.
But this is not the main reason for doubt. Over the last 60 years, millions of adolescent nicotine users have grown up as smokers and either continue to use nicotine or have quit. The problem for the Surgeon General and others is that there is no sign of any cognitive impairment in the population of former teenage smokers and many of today’s finest adult minds were once young smokers. If a detrimental cognitive effect of nicotine existed in the human population, it is inconceivable that we would not already have seen extensive evidence of it from the study of smokers, non-smokers and ex-smokers over several decades."

2018 Nora Volkow MD (NIDA) comparing youth nicotine use with marijuana use

"When it comes to determining what will make humans healthy and disease-free, research involving mice has had remarkably few successes."
"As soon as journalists see the word “mouse” in a study (or “rat,” “hamster,” etc.), they should put down the press release, delete any related emails, and refuse to write a word about that study. As a society, we waste billions of dollars and innumerable hours pursuing remedies and diets and exercise plans that may not even work in humans. The media bear a great deal of responsibility for this. To be fair, there have been many instances in which a reporter has pointed out that the study featured in his or her article was conducted on mice and may not be applicable to humans. But this is not nearly enough. When readers see a “breakthrough” treatment or diet plan advertised in the headline, they have already been misinformed — even if there is a modest disclaimer several paragraphs later."