Leading article: Addiction is more than just a lack of self-control

The notion that food might be addictive is a seductive one. And heavy over-eating can share many of the psychological characteristics associated with drug use, say, or compulsive gambling.

Similarly, the internet is changing the way our brains work, interfering with opioid and dopamine levels, according to neuropharmacologist Susan Greenfield. Some writers, Zadie Smith and Nick Hornby among them, are now using software to block access, to overcome the addictive distractions of web browsing.

But we should be wary nonetheless. With all due sympathy to those extreme cases with a genuinely pathological problem, too easily branding unhealthy activities as "an addiction" can be an excuse for bad behaviour for the rest of us. Turn off the computer. Eat less. There is merit still in the old virtue of self-control.