PhotoThe health risks of smoking while pregnant are well known. The Centers for Disease Control and Prevention (CDC) states that pregnant women who smoke, or are exposed to secondhand smoke, during pregnancy are more likely to experience pregnancy complications, including birth defects and even miscarriage.

The health concerns attributed to smoking don’t stop after birth, though – and not all of them relate to physical health. A new study conducted at Yale shows that early exposure to nicotine can change a baby’s brain chemistry. This can lead to behavioral changes, as well as the development of disorders like attention deficit and hyperactivity disorder (ADHD), addiction, and conduct disorder.

Changing brain chemistry

Researchers came to these conclusions after conducting a study that tested the effects of nicotine on mice. They found that nicotine is able to affect the way that synapses are formed between brain cells by changing the way that a master regulator packages DNA. This affected the way that mice paid attention to different stimuli.

“When this regulator is induced in mice, they pay attention to a stimulus they should ignore,” said senior author Marina Picciotto. In other words, it affected how the mice focused on the world around them, a symptom that is indicative of ADHD and other behavioral disorders.

Additionally, the researchers found that mice who were exposed to nicotine early in their development displayed these same behavioral problems later in life. A genomic screening confirmed that these mice had higher levels of histone methylation, a key regulator that controls how DNA wraps around chromosomes.

Understanding effects of nicotine

Young mice were not the only specimens that were affected by changes to regulators in this way. The researchers found that adult mice who had histone methylation inhibited became calmer -- but when these levels were increased (mimicking the effects of nicotine), these mice also exhibited behavior that was indicative of ADHD.

The researchers believe that these regulators could be the key to understanding how nicotine can affect brain chemistry.

“It is exciting to find a signal that could explain the long-lasting effects of nicotine on the brain cell structure and behavior,” said Picciotto. “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.”

The full study has been published in the journal Nature Neuroscience.


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