Excessive behaviour on its own does not mean someone is addicted.

I can think of lots of people who engage in excessive activities but I wouldn't class them as addicts as they don't appear to experience any detrimental effects from engaging in the behaviour.

In a nutshell, the fundamental difference between excessive enthusiasm and addiction is that healthy enthusiasms add to life whereas addiction takes away from it.

For any behaviour to be defined as addictive, there have to be specific consequences such as it becoming the most important activity in the person's life or being the way they improve their mood.

They may also begin to need to do more and more of the activity over time to feel the effects, and experience physical and psychological withdrawal symptoms if they can't do it.

This may lead to conflict with work and personal responsibilities, and people may even experience "relapses" if they try to give up.

The way addictions develop - whether chemical or behavioural - is complex.

Addictive behaviour develops from a combination of a person's biological/genetic predisposition, the social environment they were brought up in, their psychological constitution - such as personality factors, attitudes, expectations and beliefs, and the activity itself.

Many behavioural addictions are "hidden" addictions. Unlike, say, alcoholism, there is no slurred speech and no stumbling into work.

However, behavioural addiction is a health issue that needs to be taken seriously by all those in the health and medical profession.