In the early 1990s, a group of researchers working at the National Institute of Mental Health in Bethesda, Maryland, began a project that would become the first of its kind.
The aim was to find out why some people in the United States were more likely to suffer from schizophrenia or bipolar disorder than others.
They used a simple, inexpensive test that had already been developed in the 1950s.
In this case, it had two parts.
It measured the electrical activity in people’s brains as they made decisions.
The second part measured how quickly the brain responded to those decisions.
They did this by asking participants to sit in a room with a screen and to turn their head to the right, to a side or to the left.
The test was a little more sophisticated than the others.
It asked them to make a series of complex choices.
They had to answer yes or no.
And then the researchers asked them whether the choices they had made were correct or incorrect.
In the US, the questions were more complex than those used in Europe and Australia, but in general they asked the same thing.
Some people who did well on the first part would not do well on either the second or third part, so the test produced a false negative rate of 0.05%.
But the results were so similar to those in other studies that the scientists said the results might be true.
They even said that they could rule out the false negatives.
It was a landmark study.
The American Psychiatric Association (APA) decided that the test was valid.
It did not publish the results because it was considered unethical.
A few years later, the APA published a new version that included more sophisticated questions and more sensitive testing.
It gave people a score based on how many correct answers they got.
They got it by averaging them.
In 1998, the American Psychiatric Associations (APAC) announced that it was withdrawing the test from use.
It had been shown to have a false positive rate of up to 4% and a false-negative rate of 4% (the latter of which had been used by the US government as a measure of mental illness).
This means that about 1 in 10 Americans are likely to have some form of schizophrenia or a bipolar disorder, according to a study published in the American Journal of Psychiatry.
That is about the same rate as the British.
This is not a new problem.
As the APAC has been withdrawing the tests, the number of people who are diagnosed with schizophrenia has been rising.
There are now more than 100,000 Americans who have a diagnosis of schizophrenia.
And it is getting worse.
In recent years, there have been more than 2,000 new diagnoses for bipolar disorder in the UK and about 1,000 in the Netherlands, according the Institute of Psychiatry, London.
People who have schizophrenia often feel that they are being singled out by their peers.
And they have difficulty finding a job.
But in the past few years, the numbers of diagnoses have risen in many other countries.
People in Australia, for example, have reported more than 200 new diagnoses of schizophrenia in the last 12 months.
In Britain, the figure has been about 200.
And in the USA, it is up to 1,600.
A recent study found that the number who are considered at high risk of developing schizophrenia in adulthood increased by a factor of 20 in the years after the British and US withdrawal from the tests.
The researchers attributed the rise to a number of factors, including the rise in the number in the general population who have been diagnosed with the illness, and to increased attention paid to the disorder in children.
But the authors did not provide a clear explanation for why the number increased.
There is no definitive explanation yet.
One possibility is that the diagnostic changes made in the 1990s may have influenced the way the tests were used in the early years of the diagnosis.
It is possible that the tests may have become more sensitive and, therefore, more accurate.
But other factors may also be at play.
There may have been some sort of genetic influence on the results, says Professor Andrew King, an expert in neuropsychiatric diseases at the University of Cambridge.
If so, this might explain why there is a higher rate of schizophrenia among people who live in the developing world.
But it is still a big mystery.
Is it because we are being tested for things that are not in our genes?
What is causing it?
The APA, for its part, has issued a warning about the potential dangers of these tests.
It says that if you take the APAP test, be it a full or partial screening test, you should always take the whole test, not just the parts that are most relevant to the diagnosis of your disorder.
The results are usually the same for all participants.
The APAC is now also calling for the development of a diagnostic test that is more sensitive.
It also says that people who have severe mental illness should not take the tests because they are not always accurate.
If the APACC and the NHS