A GENERATION of children risk forming an addiction to devices such as smartphones, games consoles and televisions in the way drinkers and drug users become dependent on substances.

Dr Aric Sigman, a clinical biologist and psychologist, said heavy users of "screen media" could see long-term changes in the brain due to excessive production of the chemical transmitter dopamine.

Dopamine is central to the brain's reward system and released in response to novelty and stimulation. Production is known to rise quickly when playing computer games or watching fast-paced pop videos but the chemical is also heavily linked to addictions and accelerated by drugs, including cocaine and methamphetamine.

Dr Sigman, in his research due to be presented to The Royal College of Paediatrics and Child Health annual conference in Glasgow today, said there was considerable potential for young users to develop problems, as screen time hits an all-time high for 10 and 11-year-olds who spend an average of 6.1 hours a day looking at such devices.

Dr Sigman said: "There are concerns this may alter rewards circuitry which means the user will need to spend more screen time to get the same buzz.

"Previously a child would put £1 in a machine at an arcade and the experience would be over in 10 minutes, but now we are talking about hours of this experience every day. We don't think of experience as something linked to dependence, we only think of a substance.

"Increasing daily dopamine release in reaction to hours of computer games and other screen media is becoming a real possibility with important potential consequences."

Dr Sigman found 10 and 11-year-olds now have access to an average of five screens at home, with young people often looking at two or more screens at the same time. By the age of seven, a child born today will have spent the equivalent of one full year watching screen media 24 hours a day, Dr Sigman said.

Authorities in the US and Australia have recommended no screen time for children aged two and under and Dr Sigman has called for the threshold to be extended to three-year-olds. He also recommends a two-hour daily screen limit for young people aged up to 18.

As well as changes in the brain and increased likelihood of type 2 diabetes and poor cardiovascular health, Dr Sigman said there was a "strenuous link" with attention problems and high dopamine levels.

He added: "Whether children or adults are formally 'addicted' to screen technology or not, many of them overuse technology and have developed an unhealthy dependency on it."

Iain McCrae, from Knightswood in Glasgow, is only four but has a child's touch-screen tablet and often uses his sister's iPad to play more advanced games.

His father Gordon said: "Iain is amazing, the whole thing just comes naturally to him and his gran can't believe he can pick it up, put in a password and start playing games."

As well as an iPad, his sister Heather, 11, has a laptop, a Blackberry phone and a television in her room.

Mr McCrae, who works for a mental health organisation, said: "We had to limit the time Heather was on the iPad. She uses it for homework, but her own use was a bit excessive."