Researchers identify brain network linked with addiction

First up in the news this month, could this common brain network associated with addiction prove key to helping people overcome it? Time to introduce our first contributor, Stephanie Brown from the University of Cambridge’s Department of Psychiatry...

James - How are you doing, Stephanie?

Stephanie - Yes, I'm very good. Thank you.

James - Delighted to have you with us. So psychiatry, the medical specialty dealing with the treatment and prevention of mental health conditions. Before we get into the research you'd like to share with us today, I wonder if I could start by asking you to tell me about your particular research interests day to day. What are the conditions you study in the most depth?

Stephanie - So my specialty overall is brain imaging, but in particular MRI. We look at Alzheimer's disease, we have an avenue of research also to look at the behavioural difficulties in Prader-Willi syndrome, and there's also an avenue of research into appetite and obesity as well. So it's really a broad church, brought under the umbrella of brain imaging.

James - MRIs, brain scans - psychiatry is different from other branches of medicine, isn't it, in that diagnosis is made more difficult by the fact there are often no or very few independent markers to help with that process. We can't always run a test or do a brain scan to categorically say that our opinion of your condition is validated. Is that a fair assessment?

Stephanie - Yes, that's very true. So the difficulty that we have is that the brain is very complicated and brains differ between people and differ in various different disorders. Brain imaging has taken us a long way forward in understanding what can change in the brain in certain mood disorders and a whole range of things. MRI is a broad field, there's lots of different techniques. You can look at brain structure, brain function, the metabolites in the brain, and we can look at these in a variety of different ways, and that's what makes it such a interesting field to try and drive forward.

James - Very well put. Let's move on to the study you're bringing to the table today. It was conducted at the Brigham and Women's Hospital in Boston in America, published in Nature Mental Health. If you can, Stephanie, could you start by summing it up for us in a sentence?

Stephanie - So the researchers have analysed data from 144 studies across different forms of brain imaging and substance abuse disorders and they've found a common brain network that's linked to addiction.

James - Okay. So we're talking about addiction, substance use disorder. We probably better start by outlining from the scientific standpoint what we know about it as a condition.

Stephanie - So we know that addiction is a condition that involves compulsive seeking and taking of a substance or performing an activity despite negative or harmful consequences. And it can really impact on health, relationships, and overall quality of life. But addiction doesn't happen from having a lack of willpower or as a result of making bad decisions. We know that the brain chemistry changes. This research is specifically focused on substance use disorder, as we mentioned, and that includes addiction to alcohol, nicotine, heroin, and cocaine. So these substances are all very different from each other, but they all strongly activate the reward centre of the brain and produce feelings of pleasure. Substances also send massive surges of dopamine through your brain too. So instead of motivating you to do the things that you need to do to survive, such as eating, working, and spending time with loved ones, massive dopamine levels can have really damaging effects on your thoughts and feelings and behaviours as well.

James - This study's looking more into the particular brain patterns that people with addiction share, and I suppose therefore what we can do to help them.

Stephanie - Yes, that's right. So when we look at a brain scan or a number of brain scans like this, we can look at brain function. And what this paper has been really quite groundbreaking in identifying is this common network between people who have different substance abuse disorders. And that gives us the opportunity to 1) understand more about addiction, and 2) potentially target treatments to it.

James - And what would those treatments look like?

Stephanie - So one of the things that have been put forward by these researchers is the potential for neurostimulation therapies. Neurostimulation is basically the purposeful modulation of the nervous systems' activity using invasive or non-invasive means. So examples of these brain stimulation devices can include vagus nerve stimulation or deep brain stimulation, which you might have heard of.

James - It's a way of encouraging the brain to form new pathways and to rectify, I suppose, the changes that have caused this harmful behaviour?

Stephanie - Yes, potentially. So essentially it might be seen as rewiring or encouraging rewiring of the brain that might rectify some of this behaviour. And they are seen to be effective in treating some cases of epilepsy, neuropathic pain and other medical problems, but there is still really ongoing investigation into using neurostimulation to treat a wide range of disorders. Results are appearing very promising, but there's still much more research to be done in this field.

James - But the thinking is, through this research, narrowing down the brain networks we think are correlated with substance use disorder, we can improve the efficacy of these treatments perhaps?

Stephanie - Yes. So this paper specifically looked at functional connectivity, which is essentially coupling of brain regions in their activity. So instead of focusing on an isolated brain region, this takes a fuller view of the brain and considers how the brain acts essentially as a series of networks and interconnected circuits. There is a lot of variation in the literature about identification of these networks, but this common network tells us more about how the brain functions during addiction and may provide a target for neurostimulation.

James - The phrase that's coming to mind is correlation not being causation here, and that's kind of where we're at.

Stephanie - That's very key, yes. Correlation does not equal causation, and this is one of the challenges in this kind of research. It's very difficult to establish causation. So, as I say, we would need to look further into this common network to see if it really is a cause or an effect of substance use disorder.

James - Interesting stuff. Let's hope neurostimulation develops as we hope it will. Thank you for that, Stephanie.