Smoking and obesity could both cause permanent hearing damage, say scientists. Either could threaten blood flow to the ear, they say, with damage levels clearly linked to the level of obesity or the length of a smoking habit.

Sex therapists would argue it is a real addiction with serious consequences. But others in psychiatry and psychotherapy argue it is not comparable to substance addiction and should not be classed as such.

Brain scans have revealed a possible biological basis for cocaine addiction which may explain why some get hooked, while others can use the drug socially. The scans show cocaine alters parts of the brain controlling behaviour and appropriate decision-making.

A growing number of people are becoming addicted to their mobile phones, Blackberries and other digital devices, researchers are warning.

Taking exercise, not drinking too much alcohol, eating enough fruit and vegetables and not smoking can add up to 14 years to your life, a study says. Research involving 20,000 people over a decade found those who failed on all criteria were four times more likely to have died than those who succeeded.

Serious alcohol abuse among those too young even to drink legally is rising sharply. At a centre for children and teenagers affected by addiction, one 16-year-old tells his story.

As a hospital doctor I see people in their twenties and thirties every month with liver disease. More and more young people, especially young women, are developing this silent disease, often without the faintest idea their drinking was harmful.

Doctors are seeing rising numbers of patients in their late teens and early 20s with severe alcohol-related disease, many of them women.

Experts are warning that many more people than thought may be putting their health at risk by excessive alcohol consumption. The Office for National Statistics has revamped its assessment method to take account of bigger glasses, and the increased strength of alcoholic drinks.

Inhaled cannabis smoke has more harmful toxins than tobacco, scientists have discovered. The Canadian government research found 20 times as much ammonia, a chemical linked to cancer, New Scientist said.