Detailed studies of the disorder were first carried out by American psychiatrists in the 1950s.
If agreement can be reached, American psychiatrists hope to visit Soviet mental hospitals early next year.
Lawrence Kolb, 95, American psychiatrist, leader in community mental health movement.
The American psychiatrists would be allowed to bring their own interpreters.
But some procedures remain at issue, including whether American psychiatrists would have access to the legal records of the patients.
The American psychiatrists want to see the legal records to help evaluate the charges made against the mental patients.
Treatment orientation and associated characteristics of North American academic psychiatrists.
Sexual orientation and associated characteristics among North American academic psychiatrists.
But some American psychiatrists say the British regulators acted hastily and went too far.