The Drug Class Blog

Sep 30

More on the Brain


Posted on September 24, 2013 by Daniel G. Amen, MD

A new study from UC San Francisco’s Ernest Gallo Clinic and Research Center uncovers why humans might become addicted to cocaine after just one use. Scientists found that cocaine exposure triggered substantial growth of new dendritic spines, which are “tiny, twig-like structures that connect neurons and form the nodes of the brain’s circuit wiring” in the frontal lobes of the mice studied. The area of the brain where these new spines developed is noteworthy, as the frontal lobes house the prefrontal cortex, which controls focus, forethought, judgment, impulse control, and learning from previous mistakes.

According to researchers, development of the new spines literally rewired the brain to seek cocaine and may very well explain the intense drug-seeking behaviors commonly associated with cocaine. In the study, the mice explored two chambers, differentiated by scent and design, and then formed preferences. Next, the mice were given cocaine and placed into the chamber they did not prefer.

Once put back in the chambers without the drug, the mice overwhelmingly selected the chamber they did not (originally) prefer in search of more cocaine. The change in their preference directly correlated with the observance of new dendritic spine growth in their brain cells, appearing on the day they were exposed to the cocaine. Lead author of the study, Linda Willbrecht said, “We’ve long known that when you become a repeated drug user, the search for more drugs tends to dominate your attention and decision-making. But it’s quite shocking that these neurological changes happened after just one use.”

These findings are particularly alarming when considering how cocaine affects people with already-impaired frontal lobe activity, such as those with ADD/ADHD. Both cocaine and stimulant medications work in the same parts of the brain, yet cocaine has a much more powerful and immediate effect that stimulates an enormous release of the neurotransmitter dopamine. The effect of cocaine rapidly fades, leaving a strong desire for more. For those with impaired frontal lobes, cocaine has the potential to quickly override all other priorities and goals, setting the user up for a life in shambles.

The good news is that brain cells are constantly forming and losing dendritic spines, so the fast rewiring that occurs with cocaine exposure has great potential for being reversed through adopting brain-healthy behaviors.

What do you think?

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