Jonathan likes a drink. Like a lot of people, sometimes against his better judgement he decides to take one too many drinks and inevitably ends up regretting it.

Thankfully for him this has never become a major problem. Yet we Irish know better than most that drinking and indeed many other behaviours can become very destructive very quickly.

So where is the line between want and need, choice and compulsion and what can science tell us about addiction? 

Judith Grisel, is a former addict, a professor of psychology at Bucknell University and author of Never Enough: The Neuroscience and Experience of Addiction