The distinguished scientist Dr Nora Volkow gave this year’s Paykel lecture titled “Brain on Drugs: from Reward to Addiction” on 8 September. Dr Volkow is head of the National Institute on Drug Abuse in Maryland, USA.
The programme started with an introduction by chairman Professor Ed Bullmore. He described Dr Volkow’s outstanding research career, which has largely focused on addiction and its effects of the brain. Professor Bullmore said: “it takes passionate commitment to lead as a scientist and to lead a big organisation at the same time”.
Dr Volkow then delivered the Paykel lecture. She started by saying that she has always been passionate about science. As a committed person, she said she: “cannot think of a more rewarding area – people pay you to think and to explore the world”.
The research question that has been fascinating her relates to the effect of the neurotransmitter dopamine in addiction: what is the difference in the brain between a person who takes cocaine only once, and someone who is addicted to the drugs?
An early theory of addiction was that addicted people experience the drug as more rewarding. Dr Volkow explained the involvement of dopamine and some of its receptors in reward. She was interested to find out if the dopamine system is affected by addiction. If addicted people really do experienced drugs as more rewarding, they would show increased dopamine release in response to them. Quite surprisingly though, the opposite proved to be true. Healthy control subjects and cocaine abusers were intravenously given Methylphenidate, a drug commonly used to treat Attention Deficit Hyperactivity Disorder (ADHD). While healthy subjects responded with a strong release of dopamine, this response was dramatically lower in those addicted to cocaine.
Dr Volkow continued to explain that there is an imbalance in the dopamine system. A very important receptor in the dopamine system is D2R. Its levels are decreased in cocaine abusers and Dr Volkow speculated that higher D2R levels might protect against addiction. Her research team explored ways of manipulating D2R levels in rats which showed a preference for alcohol. Using a virus, the team was able to increase the levels of D2R in the rats’ brains. This increase lead to a dramatic reduction in alcohol intake.
Dr Volkow called this: “an exciting possibility of future treatments” if we were able to increase the D2R levels in the brain of addicted people. She added that cocaine abusers and other addicted groups show reduced activity in the prefrontal cortex, which is an important brain area for self-control. This could have important implications for treatment success. When fighting addictions “we need to do more than tell people to stop”, according to Dr Volkow. We need targeted treatments based on neuroscientific evidence.
Dr Volkow’s lecture was followed by a vote of thanks by Professor Barbara Sahakian. She said that she “admired Dr Volkow greatly” for being “a leader in the field, a fantastic mentor, and exceptional role model for women scientists”.
Written by Julia Gottwald.