Nicotine remains one of the most highly addictive substances. Although the percentage of smokers has declined in the United States, the prevalence of smoking in individuals with Attention Deficit Hyperactivity Disorder (ADHD) persists. To better understand the neuro-biological basis of this comorbidity, we have focused on a prospective preclinical design.

The Spontaneously Hypertensive Rat (SHR) has been extensively utilized as an animal model of ADHD with research supporting face, construct, and predicative validity measures. The contribution of the dopaminergic system is of major interest primarily due to the successful use of methylphenidate and other stimulants in treatment. However, much consideration has been given to dopamine's role in the reward and addiction aspects of nicotine use in ADHD.

The current study was designed to assess the role of dopamine in the prefrontal cortex, a region critical to cognition, after exposure to chronic nicotine. Nicotine was chronically delivered to SHR and control animals via alzet mini pump. Dopamine was measured via microdyalsis, in freely moving animals, on either day 4 or 11 of chronic nicotine exposure.

Our findings suggest that prefrontal cortex dopamine levels increased two-fold in the ADHD animals compared with controls, suggesting that the use of nicotine by ADHD sufferers may be associated with cognitive enhancement. This current preclinical study support reports illustrating that cognitive aspects were most closely linked to tobacco use in adolescence with ADHD.