But as publisher of The Los Angeles Times, and later as chairman of CNN, Johnson had to put on a happy face.
Most of his co-workers had no idea he was suffering from depression, and no idea that the boss was sometimes too miserable even to leave his office.
"I kept it private for fear that it would be seen as weakness," Johnson said.
He waited until after he left CNN to make his depression public because he didn't wanted his work evaluated.
"There's no doubt that there's tremendous stigma about depression, even now," says Dr. Charles Nemeroff, chief of the Department of Psychiatry at Emory University. "Even with all the public awareness campaigns."
Nemeroff helped Johnson get his depression under control through a combination of therapy and medication. The doctor says it's important to understand that depression is a disease.
For a long time, he explained, people in America thought depression was only in the mind and sufferers of the disease were complainers and wimps.
"I think some people feel differently now," said Nemeroff. "But I think a lot of people don't feel differently. And they just don't get it. And it's a big, big problem."
A new National Institute of Health study released the past week finds that though most Americans are seeking help for depression, 60 percent of those in treatment are not receiving adequate care. The study also found over the course of their lives, more than 16 percent of American adults suffer serious depression.
The impact reverberates throughout our society. Another new study estimates that the cost of depression to the U.S. economy is $44 billion a year. And, up to 90 percent of suicides is believed to be related to depression.
Nemeroff says shame about depression leads many not to seek help about their problem.
"Many patients will say, 'I just can't go to a psychiatrist or psychologist. I don't want anybody to know,'" he said.
But treating depression is a challenge. Fifteen years ago, there was a buzz that Prozac and other new drugs helped to control the disease with limited side effects. But they didn't work for everyone. Today, even with some 20 different medications on the market and $12 million a year spent on antidepressants, drugs fail one out of every four patients. And they lose their effectiveness for others.
Many depression patients and their families share their frustration with support groups.
Some find that drugs that are supposed to help fight depression actually make it worse, because an ineffective antidepressant can make the patient frustrated and more depressed.
But hope may be on the horizon. New technology is helping doctors at the National Institute of Mental Health compare brains of depressed patients with those of people who are depression free. A machine there takes a "PET scan," an image of a cross section of a subject's brain.
"We've been able to show with imaging that not only is the function abnormal in the brain in depression, but the structure and the receptor, the receptor chemistry are also abnormal in depression," said Dr. Wayne Drevets.
He says the part of the brain that organizes emotional response is often overactive in depressed people.
"It's as though the accelerator is on and the brakes are bad and they keep you from really controlling and stopping the emotions at a level that would be normal," said Drevets. "What we would consider adaptive and normal."
The brain scans are also beginning to show how signs of depression can vary from patient to patient, which might explain why there's no "one-fits-all" antidepressant.
Doctors say eventually they may be able to do a PET scan, an MRI scan or perhaps a blood sample to match genetics with antidepressant drug to make a patient feel better.
Dr. Raymond DePaulo of the Johns Hopkins School of Medicine is studying the DNA of depressed patients and their families.
"What we know is that it's 50 to 80 percent genetic," he said.
DePaulo and his team of researchers are on the hunt for the genes that cause depression and clues to what makes someone depressed in the first place.
"Then we could have choices about how to alter that," DePaulo explained.
He said a medication in the future may block the effects of the gene.
For now, when medication doesn't work, an estimated 100,000 patients a year are turning to an old-fashioned remedy — one that gained a bad reputation from the film "One Flew Over the Cuckoo's Nest." The controversial treatment is called Elector Convulsive Therapy (ECT).
"I was terrified," said Kitty Dukakis, wife of 1988 presidential candidate Michael Dukakis. "This is my head and my brain and my being."
When Dukakis' husband lost the election, she came forward to acknowledge her depression and the fact — like many with the disease — she had turned to alcohol to dull the pain.
"I realize now that I am an alcoholic," said Dukakis.
She got sober, went into treatment for depression and even wrote a book about her ordeal. For a while she was better, but eventually the antidepressants stopped working.
"Usually, after eight months of being depression free, I knew that at some point, it was going to hit. And it hit with vengeance," she said. "It's a lowering of everything, as far as my personality was concerned, of everything that's a part of me. Low self-esteem, inability to get anything done, sadness, a horrific sadness."
A year and a half ago, her doctors convinced her that electro-shock was her best option — explaining how the procedure has changed. Today, patients get anesthesia, the dosage is lower, electrical current passes through the brain for less than a minute. And there are no major convulsions, only a wiggling toe.
"I felf relief almost immediately. I had told Michael that morning, 'I'm not sure we're going to be able to go out and celebrate our anniversary'" she said. "And the first thing I said to him when I saw him [after the shock treatment] was, 'I want to go out and celebrate.'"
Like most modern ECT patients, Dukakis had the treatment three times a week for six weeks. She has been free from depression for 18 months. Though she did have some memory loss about the periods shortly before and after the therapy, she has no regrets.
"There is no down side," said Dukakis. "I will accept whatever it is because the result, the overall result, is so positive."
Dr. William McDonald runs the ECT clinic at Emory University's medical center. He says that ECT does help most people who try it. Older patients seem to respond better than younger ones, he explained, but it doesn't work for everyone. Doctors are experimenting with other treatments, such as a procedure known as TMS, which is now in a clinical trial at Emory.
He said TMS excites the brain in a different way than the ECT procedure — using electro magnetic currents.
Some patients have claimed increased energy after the TMS therapy.
Doctors are saying there are various options for those suffering from depression.
"It's going to take both the brain scientist and the geneticists and the psychiatrists all working together," said Dr. Raymond DePaulo. "And it's going to come together like a Rubik's cube does … You're not going to know whether you're one move away from the solution or 50."