Pregnant women who have yet to quit smoking may now have another reason to do so.
A pair of recent studies have found further evidence that maternal smoking can lead to behavioral health problems such as schizophrenia and attention-deficit/hyperactivity disorder (ADHD).
The first study, which was published in theAmerican Journal of Psychiatry, analyzed data on patients born in Finland between 1983 and 1998, among whom there were nearly 1000 diagnosed cases of schizophrenia.
Among patients with schizophrenia, 20% were born to mothers who smoked heavily during pregnancy; comparatively, only 14.7% of those without the mental health disorder were exposed to maternal tobacco use.
After controlling for factors such as socioeconomic status and maternal age, the researchers determined that heavy maternal nicotine exposure was associated with a 38% increased risk of schizophrenia.
“These findings underscore the value of ongoing public health education on the potentially debilitating, and largely preventable, consequences that smoking may have on children over time,” stated senior author Alan Brown, MD, MPH, who had previously established a similar association between maternal smoking and bipolar disorder. “Future studies on maternal smoking and other environmental, genetic, and epigenetic factors, as well as animal models, should allow identification of the biological mechanisms responsible for these associations.”
A separate study published inNature Neurosciencesought to better understand some of these mechanisms. Researchers exposed a group of mice to nicotine during their early development and found that many of these mice exhibited symptoms comparable to ADHD in humans.
After they performed genomic screening of the mice, the researchers found higher levels of activity in a key regulator of histone methylation—the process through which chromosomes are formed and genes are expressed.
The genes responsible for the creation of brain synapses were also heavily affected by nicotine exposure. These genetic changes remained in adult mice.
Notably, the mice no longer displayed symptoms of ADHD after the researchers inhibited the master regulator of histone methylation. Similarly, triggering the expression of this regulator in mice not exposed to nicotine led them to exhibit ADHD-like behavior.
“It is exciting to find a signal that could explain the long-lasting effects of nicotine on brain cell structure and behavior,” said senior author Marina Picciotto, PhD, in a press release. “It was even more intriguing to find a regulator of gene expression that responds to a stimulus like nicotine and may change synapse and brain activity during development.”