Stressing the harmful effects of smoking by mothers during their pregnancy, a new study by Yale University reveals that a baby’s early exposure to nicotine can trigger widespread genetic changes that have consequences long after their birth. The finding that early nicotine exposure affects formation of connections between brain cells could explain why maternal smoking has been linked to behavioral changes such as attention deficit and hyperactivity disorder, addiction and conduct disorder in children.
Nicotine does this by influencing the activity of genes crucial to the formation and stabilization of synapses between brain cells. An inability to focus is the hallmark of attention deficit hyperactivity disorder and other behavioral disorders, which have been linked to maternal smoking and exposure to second-hand smoke. However, scientists did not understand how early environmental exposure to smoking could create behavioral problems years later.
The new study found that mice exposed to nicotine during early development did indeed develop behavioral problems that mimic symptoms of attention deficit disorder in humans. The researchers then did extensive genomic screening of mice exposed to nicotine and found higher levels of activity in a key regulator that controls gene expression. The researchers found that genes essential to the creation of brain synapses were heavily affected by nicotine and that the genetic changes induced were maintained even in adult mice.