Cocaine addiction leads to iron build up in the brain

Cocaine used to be the drug of the rich and famous, but over recent years it has become cheaper and more readily available, and as a result more and more people are becoming addicted to this highly dangerous substance. A report last year from the UK Government Advisory Council found that 1 in 10 people between the ages of 16 and 59 had used the drug at some point. The current treatment for cocaine addicts is through therapy, but relapse rates remain high. Now a new study has linked cocaine addiction with a build up of iron in certain parts of the brain, and particularly areas known to control our inhibitions, although the team don’t yet know what the iron is doing there. Tom Crawford spoke with lead author Dr Karen Ersche...

Karen - We found, for the first time, that people with cocaine addiction have disruptions in their regulation of iron and we find that they have reduced iron levels in the blood, and increased levels of iron in the brain.

Tom - What did you do in this study to find these results?

Karen - We asked all our participants to have a brain scan. We used a very specific scanner and with this estimate how much iron in the brain, and we also took blood samples and did the standard test.

Tom - An accumulation of excessive iron is actually very bad as it’s highly toxic and can lead to cell death. Similar examples can be seen in other brain degenerative diseases such as Parkinson’s and dementia. But in terms of cocaine addiction, the iron doesn’t appear everywhere.

Karen - The increase in iron was very specific in the brain. It was selective in the globus pallidus, which is a nucleus deep down in the brain and it’s involved in inhibition. We know that people with cocaine addiction have problems with inhibition. The globus pallidus is also involved in avoidance learning, which we know that people with cocaine addiction have problems avoiding adversity. So it is tempting to speculate that we have found here an angle which might be related to problems that we see in the clinic.

Tom - Now that you’ve discovered this link between build up of iron in the brain and lower levels of iron in the blood, and this link to cocaine addiction, could this lead to new treatments, new preventative measures? What are the possibilities here with this discovery?

Karen - First of all we need to address two critical questions. We need to find out what is causing this, so how is cocaine disrupting iron regulation and their different possibilities. One would be chronic cocaine users are vulnerable to infection and inflammation and this could disrupt iron homeostasis.

On the other hand we also know that cocaine users have quite an appetite for fat and fatty food which could hamper the absorption of iron. Another possibility would be that cocaine destroys or weakens the blood/brain barrier so that more iron leaks into the brain.

We also need to find out what this build up of iron is actually doing in the brain that’s associated with the severity of the addiction. So we found a relationship with the amount of iron accumulated and the duration of cocaine use.

Tom - So, I guess, to come up with new possible treatment methods by understanding more about the effect that cocaine has on the brain, this hopefully will lead to potential new avenues of treatment is possibly one of your future goals?

Karen - Yes, that’s right. And I think there’s quite a lot of literature out there on the changes that we see in the brain, but we know very little about the mechanism of how these changes come about. What is the role of cocaine and how does cocaine interact with brain cells? If cocaine interferes with iron regulation, iron metabolism, that would be really a new avenue to provide treatment.