How does maternal smoking influence ADHD gene expression? 

Studies show that maternal smoking and ADHD risk are linked by more than statistics; they may involve biological changes at the level of gene expression. When a developing foetus is exposed to nicotine and other chemicals in cigarettes, this prenatal exposure can cause epigenetic changes that disrupt brain development, particularly in areas linked to attention, impulse control, and emotional regulation. 

What happens in the womb? 

Nicotine and other toxins in cigarettes cross the placental barrier, exposing the foetus to substances that can interfere with normal brain wiring. But beyond physical effects, maternal smoking also alters the way genes function, particularly genes involved in dopamine signalling and neurodevelopment. 

DNA methylation shifts 

Research shows that prenatal exposure to tobacco smoke can modify DNA methylation patterns in genes like DAT1, DRD4, and CHRNA5, which play key roles in regulating attention and reward pathways. These modifications can persist into childhood and even adolescence. 

Disrupted neural pathways  

Altered methylation can lead to overexpression or underexpression of critical genes during foetal development, affecting how the brain circuits mature particularly those involved in executive function. 

Increased risk of ADHD symptoms  

Children exposed to maternal smoking in utero are more likely to display inattention, hyperactivity, and emotional reactivity, core features of ADHD. These effects may be amplified in children with existing genetic vulnerabilities. 

Why it matters 

Maternal smoking does not just increase ADHD risk; it may shape how ADHD genes are expressed. This adds weight to public health efforts aimed at smoking cessation during pregnancy and highlights the role of early environments in shaping lifelong brain health. 

Visit providers like ADHD Certify for personal consultations that explore prenatal and epigenetic influences on ADHD.

For a deeper dive into the science, diagnosis, and full treatment landscape, read our complete guide to Genetic studies and biomarkers.