Celebrities who knew and worked with Koenig are also mourning his death.
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Andrew Koenig may be best remembered for his role as "Boner" on the 1980s sitcom "Growing Pains," but his more lasting contribution may be lifting the lid off depression.
Kirk Cameron, who played alongside him on "Growing Pains," told US Weekly: "It is with great sorrow to hear about the final outcome of the search for my old friend Andrew. I hope everyone will be sensitive to the Koenigs and give the family some private time to reflect and to grieve the loss of their beloved son. At a time like this, we are all reminded of the briefness of life and the importance of being ready for our eternal destination. My prayers will continue to be with Andrew's family."
Their co-star Tracey Gold expressed her condolences.
"Today is a sad day," she said. "My heart is broken for Andrew's family. I have such great memories of Andrew and our time together on Growing Pains."
Other celebrities remembered Koenig, via Twitter:
Sarah Silverman: "My heart is heavy for the Koenig family."
Alyssa Milano: "RIP"
"Star Trek" costar William Shatner: "My deepest sympathies to Andrew Koenig's family. I will grieve with them."
Today, many are applauding the family's decision to speak out about Koenig's depression.
"Part of what's so impressive is that they are talking publicly rather than feeling stigmatized," Nadine Kaslow, chief psychologist and vice chair at Emory University School of Medicine in Atlanta, told ABCNews.com. "They are working to reduce the stigma we have about depression and suicide."
Depression is one of the biggest risk factors for suicide, Kaslow said. Usually caused by biological factors, it can be exacerbated by stress. The earlier the onset of depression, and the more it reoccurs, the more difficult course it takes.
For most people suffering from depression, psychotherapy or medication or a combination of both can be used to treat it.
Walter Koenig said his son stopped taking his medication about a year ago. Kaslow said some people can go off their medication, whereas some people will need it for the rest of their lives.
Koenig's friends said he was up front about his battle with depression.
"He faced it, didn't shirk it," Lance Miccio, who worked with him on several film projects, told ABCNews.com. "He received treatment for it. It was a day-to-day thing that was woven into his fabric. It never affected his work. Maybe he was a little more grouchy than usual. But he was able to deal with it."
It's also possible he got tired of dealing with it.