"When consumed at low to moderate daily doses, caffeine is a relatively safe drug," said researchers from Johns Hopkins University in Baltimore and the American University in Washington DC.
"However, for some individuals, [it] is capable of causing various undesirable effects and disorders across a wide range of doses."
In general, experts recommend that adults consume no more than 400mg of caffeine a day - or around four cups of instant coffee.
But even those who drink less can find they show signs of dependency, which include withdrawal symptoms such as headaches and fatigue if they don't get their fix.
However sufferers of the so-called disorder should not despair - because the team have also devised a treatment plan to wean people off their favourite pick-me-up. The researchers found that cognitive-behavioural therapy helps people reduce their caffeine intake dramatically over a five-week course.
In their study of 67 people, they found that participants reduced their caffeine consumption by 77 per cent, with saliva samples backing up their self-reports. More than three-quarters reduced their consumption to below 200mg a day - compared with an average 670mg a day at the start of the programme.
Much like the regimes used to ease people off other drugs, the patients followed a "caffeine fading" scheme, in which their intake was reduced gradually to make withdrawal symptoms easier to cope with. They were also given a treatment booklet to take home and use between counsellor sessions.
Professor Laura Juliano, from American University, said: "These findings show that brief therapy consisting of cognitive-behavioural strategies and gradual caffeine reduction can help individuals seeking treatment for problematic caffeine use."
She added that the study is one of the largest ever controlled clinical trials of modifying caffeine use.
However the researchers emphasised that there can be positive effects to consuming caffeine. Writing in the Journal of Consulting and Clinical Psychology, they said: "[It] offers some functional and perhaps health-protective effects, for example staying awake during a long drive."
- Daily Mail