"Whilst the story was revealed to be a hoax, it didn't mean that the condition of selfitis didn't exist.
"We have now appeared to confirm its existence and developed the world's first Selfitis Behaviour Scale to assess the condition."
The scale, which runs from 1 to 100, was developed using a large number of focus groups with 200 participants to determine what factors drove selfitis. It was scale tested using a survey of 400 participants.
Participants were based in India because the country has the most users on Facebook, as well as the highest number of deaths as a result of trying to take selfies in dangerous locations.
The findings, published in the International Journal of Mental Health and Addiction, described three levels of selfitis. Borderline cases are people who take selfies at least three times a day, but do not post them on social media. Next is the acute phase where the pictures are posted.
In the third chronic stage, people feel an uncontrollable urge to take photos of one's self round the clock, posting them more than six times a day.
The team developed 20 statements that could be used to determine the severity of selfitis by rating how much an individual agreed with the sentiment. Examples include "I feel more popular when I post my selfies on social media" or "When I don't take selfies, I feel detached from my peer group."
Dr Janarthanan Balakrishnan, a research associate from Nottingham Trent's Department of Psychology, said: "Typically, those with the condition suffer from a lack of self-confidence and are seeking to 'fit in' with those around them, and may display symptoms similar to other potentially addictive behaviours."
Other related mental health disorders identified in recent years include "nomophobia" the fear of not being near a mobile phone and "cyberchondria", feeling ill after searching online for symptoms of illness.
Sir Simon Wessely, Professor of Psychological Medicine at King's College London, was more sceptical about the proposed new condition.
"The research suggests that people take selfies to improve their mood, draw attention to themselves, increase their self confidence and connect with their environment.
"If that is true then this paper is itself an academic 'selfie'."
Dr Mark Salter, a spokesman for The Royal College of Psychiatrists, added: "Selfitis doesn't exist, and it shouldn't exist.
"There is a tendency to try and label a whole range of complicated and complex human behaviours with a single word. But that is dangerous because it can give something reality where it really has none."
Levels of selfitis*
Borderline: Taking photos of oneself at least three times a day but not posting them on social media.
Acute: Taking photos of oneself at least three times a day and posting each one on social media.
Chronic: Uncontrollable urge to take photos of oneself round the clock and posting the photos on social media more than six times a day.
* According to the researchers' findings