Some 300,000 United States troops are suffering from major depression or post-traumatic stress from serving in the wars in Iraq and Afghanistan, and 320,000 received brain injuries, a new study estimates. Only about half have sought treatment, said the study released yesterday by the RAND Corp.

The report is titled Invisible Wounds of War: Psychological and Cognitive Injuries, Their Consequences, and Services to Assist Recovery. It was sponsored by a grant from the California Community Foundation and done by 25 researchers from RAND Health and the RAND National Security Research Division, which also has done work under contracts with the Pentagon and other defence agencies as well as allied foreign governments and foundations.