I In the United States, the FDA's warnings target tobacco products to either the general population or only to women. There are no special men-centered warnings. The risks of smoking or smoking for pregnant women and their children have long been clear, but no one has really thought about whether a father's smoking habits could affect his or her children. For too long, we assumed that fathers are safe because they did not carry children.
However, a study published in Plos Biology on Wednesday shows that some of the effects of dad's consumption of nicotine on his children can be transferred ̵
In the FDA's current tobacco warnings, Bhide says Inverse there is "nothing about men who smoke anytime." His paper suggests that it's time this changes.
Generic Nicotine Mice Generations of Brains
The link between a mother's use of nicotine and cognitive problems such as ADHD in her children has been well established, and some prior analysis of existing data has provided a "clue" that a father's smoking the same problems with his children, says Bhide. However, the new study is the first to show that the compound is a robust phenomenon.
In the experiments, Bhide's team gave nicotine-laced water to 12 male mice during the period in which they produced sperm, and then mated those mice with women who were not exposed to nicotine. The children showed all the features such as hyperactivity, attention deficit syndrome and cognitive inflexibility that were tested on difficult mouse tasks called Barnes Maze and Y-Maze.
Using females of this generation of mice, the team induced mating with males from a separate, nicotine-free group. As the babies of this generation grew up, it was clear that the cognitive effects persisted again, but to a lesser extent.
"There was not much known about the effects of smoking on their children and grandchildren," says Bhide. "Our study shows that paternal nicotine exposure can be harmful to offspring in several generations." But what he wanted to know was like .
It is clear that nicotine-induced changes in the original "grandfather" DNA have been passed down through generations, meaning that these changes must be present in the DNA of its sperm. When the team looked at sperm from the original males, they saw that several genes carried "epigenetic modifications" – fickle physical changes to the DNA that make certain genes more or less usable. They were referred to by scientists as "ornaments on a Christmas tree".
One of the genes affected by epigenetic modifications was the dopamine D2 gene, which is involved in brain development and learning.
The team's hypothesis is that these epigenetic changes triggered by nicotine exposure were passed through the sperm of the original generation to the children of the next. The changes remained to some extent in the DNA of these children, so some "decorations" were removed from the DNA Christmas tree, so the cognitive problems in the last generation were not so robust.
Epigenetics is a relatively new field that is not fully understood. "We do not know the answers to all these things," says Bhide.
The Threat of Man
Some critics, Bhide argues, have argued that the results of his mouse study can not be applied to humans. "That's unfortunate, because at least [they could] give him a chance," he says. "There's nothing to lose by saying, 'That could happen, so be careful.'"
It is true that it was not a study on humans that shows that the effects of nicotine are passed down through generations through men. Unfortunately, Bhide says, it would be virtually impossible to do these studies, at least in the current population of potential subjects, because smoking and ADHD go hand in hand. In other words, you can not say that a child has ADHD. because her father smoked, if one can not say whether the father actually had nicotine-induced changes in his sperm or if he even wore other ADHD-bound genes. That said, there is less direct evidence, largely retrospective queries from existing data, showing that paternal nicotine exposure increases the risk of ADHD for children. "Findings from humans and animal models are fairly consistent in terms of nicotine exposure to the mother," says Bhide. "I see no reason why this should not apply to paternal studies on nicotine exposure."
What now? Apart from the usual warnings about anti-cancer smoking, Bhide says it's time for men to think that nicotine could be affected by their germ cells – their sperm – and give their children lasting changes. You should also keep in mind that the results are likely to apply to all types of nicotine use: cigarettes, e-cigarettes, vapes, JUULs and even chewing tobacco.
It is not clear how long the epigenetic effects of smoking will affect a man's semen. So it's probably safest for future dads to take the side of caution. "Our study raises concern to another level," says Bhide, "Father's Smoking Status Before and At Conception!"
Bhide and his team have taken the first important step in finding out how risky it is for future dads to smoke by demonstrating that children's cognitive effects are a real phenomenon due to their fathers' nicotine exposure.
We may not know what it is – our hypotheses may be wrong, "says Bhide," but somehow it happens. "