NRSC 4132 Blog

Think back to the high school adolescent movies that you have seen. Have you ever noticed that all the "cool" mysterious kids seem to smoke cigarettes? Most adult smokers start smoking before becoming 19 years old and 70% of young adults have admitted to trying a cigarette at least once in their life.

How about the fact that with the constant tobacco sales, we have seen an average increase of 5.5% in the rates of ADHD diagnosis every year since 2003? There is a connection! A recent study published in Nature Neuroscience shows that smoking cigarettes and exposure to nicotine during one?s adolescence may be the underlying cause of attention deficits. The study by Danielle S Counotte et al shows that nicotine exposure during these critical growing years causes a reduction in mGluR2 protein and function on the presynaptic terminals of PFC glutametergic synapses.

Counotte and her colleagues exposed adolescent rats to nicotine in order to observe the changes in attention keeping capabilities. Through the use of the 5-choice serial reaction time task, they found that nicotine exposure in adolescent rats increased impulsive behavior and impaired attention in adulthood after 5 weeks without nicotine exposure

In order to confirm that mGluR2 signalling in the PFC is involved in attention, MPPG (a mGluR2 antagonist) was infused into the mPFC of control rats. By decreasing the mGluR2 signaling in these animals, attention performance was reduced. mGluR2 receptors have been linked to the short term plasticity of glutamatergic synapses in cortical areas. Counotte further tested the role of mGluR2 in the short term plasticity of these synapses in adult mPFC and found that after 5 "clean" weeks, adolescents that were exposed to nicotine expressed less depression of mPFC glutamatergic synapses than in the rats treated with saline. A reduction in mGluR2 protein levels were also reduced in adolescents treated with nicotine. These results may explain the observed reduction in mPFC function and a lack of ability to pay attention.

This study also found that nicotine exposure during adulthood, however, did not affect mGluR2 protein levels after 5 weeks of abstaining from nicotine and did not reduce synaptic depression. Instead a slight increase of depression was observed; thus indicating that mGluR2 levels in the PFC are developed during and are particularly vulnerable to nicotine's effects during adolescence. Nicotine is able to pass through the blood brain barrier and binds to nicotinic acetylcholine receptors in the PFC. Huh. There is a reason why it's illegal to smoke cigarettes before turning 18!

As a nation, could we be causing our own increase in attention deficit disorders by making risky choices as young adults? This study leads me to wonder whether other ?common? ailments could be prevented if kids would just follow the rules.
For more information, this article can be found in the April 2011 issue of Nature Neuroscience and is entitled "Lasting Synaptic Changes Underlie Attention Deficits Cause by Nicotine Exposure During Adolescence".