Women are routinely warned of the dangers of smoking during pregnancy , but the effects of the father's exposure on his offspring are poorly documented. This Florida State University College of Medicine study, conducted in mice, suggests that smoking in men may also have harmful effects and specifically lead to cognitive deficits in children. It is even an effect over 2 generations that is noted here in the journal PLoS Biology. Awaiting confirmation in humans.
Data, which for the lead author, Dr. Pradeep Bhide, holder of the chair of neuroscience at the medical school, underlines the possibility that some of the cognitive impairments observed in the current generation of children are attributable to the attacks of the environment suffered for a generation or two: smoking was more common and more easily accepted by the population in the 1940s and 1960s compared to today. Could this exposure be responsible for the marked increase in the number of diagnoses of neurodevelopmental disorders such as ADHD and autism? »
The study exposed male mice to low-dose nicotine in their drinking water during the stage of development when they produce sperm. The mice were then bred with female mice never exposed to nicotine. Although the fathers presented normal behaviors, their children, of both sexes, presented hyperactivity, attention deficit and cognitive rigidity. In addition, by analyzing the father's spermatozoa, the researchers identified several genes bearing epigenetic modifications: among the genes concerned, the dopamine D2 gene, which plays an important role in development and learning. These epigenetic modifications on this gene could contribute to explain the cognitive deficits observed in the descendants.
By revealing these gene expression changes in the father's sperm clearly linked to nicotine exposure, the study demonstrates the impact of the father's environmental exposures on the future health of his children. Some of these epigenetic changes would be temporary, others could last a long time. Further research is therefore needed to estimate the duration of these changes. Unsurprising results compared to those of previous research showing that nicotine affects germ cells and / or modifies the DNA of sperm.
If nicotine exposure in women is already well documented as an important risk factor for behavioral disorders in her children, such as ADHD. In men, this study adds to the evidence of environmental risk factors impacting the health of his children.
Physicians should therefore warn men too, that their smoking can harm the unborn child. The researchers indeed conclude: “we believe that the results of our study can be extrapolated to humans”.