Not all spies target military, political or economic intelligence. Some spies gather medical intelligence. Presidents, prime ministers and other leaders do not always like to talk about their health. Some disappear from public life for a while and then reappear, with or without an explanation. Spy agencies search for information about physical and mental health. The idea that a leader might even lose his mind and launch a war or a nuclear attack is not an imaginary threat. The Central Intelligence Agency has a Medical and Psychological Assessment Cell. It employs or consults with doctors, sociologists, political scientists and cultural anthropologists to examine the conditions of top officials.Jonathan Clemente is a doctor doing research for a book on medical intelligence. He says the CIA team will look for psychiatric signs, then "describe for the policy makers how someone with that particular set of findings may react to certain situations."Such efforts go back to the Office of Strategic Services, which came before the CIA. The OSS did a psychological profile of Nazi leader Adolf Hitler in Germany. The CIA was established in nineteen forty-seven. Dr. Clemente says the agency formed a small office called "Leadership at a Distance." "In the late fifties and early nineteen sixties, the CIA decided that they had expertise to look more carefully and in a more rigorous, analytical way at the health of foreign leaders." The idea is to help give policy makers some forewarning of a transition in a government, and also to look "for potential points of diplomatic leverage."Experts say dying leaders can feel they have to act quickly to make sure their decisions live longer than they do. Physical and mental health are closely linked, experts say. But identifying a mental condition without direct examination of a person can be much more difficult than a physical disorder. Rose McDermott is a political psychologist at Brown University in Providence, Rhode Island. She says an illness like bipolar disorder can be well-controlled on medication. But a leader's behavior can also be affected by treatment for a physical condition. "The concern is not just the illness, it's also the medication that people take while they are ill and how that can compromise their decision-making ability, cognitively and intellectually. So they don't make the same kind of decisions, their decisions may not be as predictable. They certainly may not be as, quote unquote, rational."

For VOA Special English, I'm Alex Villarreal.