Association Between Smoking, Brain Activity, Genes, and ADHD

The study investigated the underlying mechanisms of smoking in young adults by examining the
associations between smoking, brain activity, dopamine genes, and attention deficit
hyperactivity disorder (ADHD). Four groups of young adults were recruited: (1) smokers with
ADHD; (2) nonsmokers with ADHD; (3) normative control smokers; and (4) normative control
nonsmokers. Smoking was assessed via questionnaires and salivary cotinine levels. Brain
activity was examined via functional Magnetic Resonance Imaging (fMRI). Each nonsmoker
underwent an fMRI scan during an experimental task consisting of mathematical problems.
Smokers underwent two fMRI scans during similar experimental tasks under the following two
conditions: (1) after smoking a cigarette and (2) after overnight abstinence. The
association between the DRD4-7 repeat allele and smoking was explored.

Inclusion Criteria:

1. Smokers with ADHD

- Cigarette smoking for the last year

- ADHD diagnosis

2. Nonsmokers with ADHD

- No history of regularly smoking cigarettes

- ADHD diagnosis

3. Normative control smokers

- Cigarette smoking for the last year

- No history and diagnosis of ADHD

4. Normative control nonsmokers

- No history of regularly smoking cigarettes

- No history and diagnosis of ADHD

Exclusion Criteria:

- Children under the age of 18

- Adults above the age of 45

- Pregnancy or planning to become pregnant

- Any major medical illness

- Any mental disorders that require medication (except stimulant medication)

- Any contraindications to fMRI scanning

- Not speaking English