An updated edition of a mental health bible for doctors could mean that soon no-one will be classed as normal, experts warned today.
Diagnoses for 'disorders' could be based on symptoms including toddler tantrums, mild mood swings and binge eating.
Sweeping changes are being made to the U.S Diagnostic and Statistical Manual of Mental Disorders (DSM), which influences practitioners around the world.
However, leading British mental health experts have warned the revisions could devalue the seriousness of mental illness and label almost everyone as having some kind of disorder.
One suggestion of the American authors is a new diagnosis of 'Psychosis Risk Syndrome' which singles out people thought to be at risk of developing a psychotic illness such as schizophrenia.
Individuals falling into this category might experience occasional mood changes, feelings of distress, anxiety or paranoia, or fleeting episodes of hearing voices.
In the past they might have been considered difficult or eccentric. Under the new proposals they could receive a diagnosis that affects their future lives and job prospects. Yet they may never develop 'full blown' psychosis.
Other diagnoses under consideration include 'mixed anxiety depression', 'binge eating', and 'temper dysregulation disorder with dysphoria'.
In addition, the bar could be lowered on some common existing disorders, such as depression, so that more people are considered to have symptoms that warrant a diagnosis.
Professor Til Wykes from Kings College London, said: 'It's leaking into normality. It is shrinking the pool of what is normal to a puddle.'
Professor Wykes edits the Journal of Mental Health which carries a "health warning" about the proposals in its latest issue.
The changes have been put forward for discussion by a powerful group of U.S experts working on the fifth edition of the DSM, which is published by the American Psychiatric Association.
The new edition, due to appear in May 2013, will provide the first update of the guidelines in 16 years.
Professor Wykes and other experts fear the draft proposals, now entering a six-month period of public consultation, could have a devastating impact both on individuals and society.
They accuse the US authors of racing ahead of scientific progress in mental health, which has made relatively little headway in 16 years.
Many of new diagnostic criteria are based on symptoms that dovetail with normal behaviour and are not sufficiently underpinned by research, it is claimed.
Prof Wykes said the "at-risk" diagnosis would lead to unnecessary psychotherapy or even medical treatments. She used the analogy of treating 10 people with common colds for pneumonia because all are considered at risk of developing a serious illness.
'The difficulty is we do not know whether you can prevent one person having a psychosis by treating everybody,' she said.
'Not only is it self defeating, but we think it will have severe consequences from the point of view of stigma, the way people view themselves, and the anxiety they might have.
'We have no test that can say that a person is going to have schizophrenia.'
The Journal of Mental Health editorial, co-authored by Prof Wykes and Dr Felicity Callard, said a diagnosis of "Psychosis Risk Syndrome" would expose many people who were not destined to develop a serious mental illness to the risk of social stigma and discrimination.
Labelling an individual at risk of a disorder 'commonly regarded with great apprehension' could even change an individual's 'sense of personhood', it was claimed.
The editorial adds: 'As well as the distress likely to be experienced by themselves and their families, and the suffering entailed by treatment irrespective of whether it is drug or psychological therapy, the logic entailed by Psychosis Risk Syndrome might also divert attention away from understanding the underlying causes of schizophrenia.'
Dr Callard, from the Biomedical Research Centre for Mental Health at the South London and Maudsley NHS Foundation Trust, said: 'If this category were to be introduced the people likely to be given this diagnosis are going to be relatively young. What are the implications of someone receiving a diagnosis that is not a diagnosis of a disorder as such, but a potential disorder?'
Both experts spelled out their views at a news conference in London today.
Colleague Professor Nick Craddock, from the University of Cardiff, said it was useful and necessary for practitioners to agree on how they identify symptoms of psychiatric disorders. But it was "highly problematic" to label traits that overlapped with normal behaviour medical symptoms.
'At what point is it right to ask to say that someone has a medical problem?' Professor Craddock asked.
Professor Wykes said the U.S. had a major influence on psychiatry and mental health research partly because most of the "high impact" journals in the field were American.
.People have used the words 'the Americanisation of mental illness' because you cannot underestimate the dramatic effect it has had,' she said.
One factor driving the American approach was the way healthcare was funded in the U.S, said the experts.
The DSM guidelines provided the means by which US psychiatrists were reimbursed by private health insurers for treating patients. A practitioner who offered help to someone who fell outside a defined diagnostic category risked not getting paid.