almost half of American presidents from 1789 to 1974 had suffered from a mental illness at some point in life, according to a recent analysis of biographical sources by psychiatrists at Duke University Medical Center. And more than half of those presidents, the study found, struggled with their symptoms — most often depression — while in office.
"What is hopeful about this is that it is evidence that people can suffer from depression or other mental problems and still function at a presidential level, if not at their best," said Dr. Jonathan Davidson

- As a young man, Abraham Lincoln experienced bouts of despair so profound that friends were concerned he might commit suicide.
Ulysses S. Grant, the general under Lincoln who later rose to the presidency, often avoided social occasions and retreated into alcohol.

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