Robin Williams' suicide highlights battle to treat depression and addiction

From the moment news broke of Robin Williams' suicide, the phones started ringing at the National Suicide Prevention Lifeline in New York, and they haven't stopped.

The past 24 hours has seen the second highest volume of calls in the last 12 months.

Lisa Furst is director of public education at the lifeline's New York City call center.

"When there is a public completion of suicide, it spurs people to reach out. Especially if they didn't know where to reach out before, as many people may not," says Furst.

The most recent numbers from the Centers for Disease Control show more than 39,000 suicides each year. That's an average of 108 suicides each day.

Dr. Jeffrey Borenstein is president of the Brain and Behavior Research Foundation.

"More people die from suicide than die from homicide in the United States, which is an amazing fact. Most people don't realize how common it is," says Dr. Borenstein.

Between a quarter and a third of people who die by suicide have a substance-use disorder, along with a diagnosable mental illness.

"I went to rehab in wine country just to keep my options open," said Williams.

While he joked about it, Robin Williams' suicide underscores this link between depression and substance abuse. Addicts have a rate of depression three to four times higher than the general public.

Williams was candid about his alcoholism. Last September, he described to Jon Stewart how easily 20 years of sobriety gave way to a bottle of Jack Daniels.

"The moment I had the first sip ... it was like ... rahhh ... all of a sudden it was like, welcome back a**hole."

Dr. Borenstein says, "If you only treat the depression without treating without treating the chemical dependency, you won't be successful in really helping the person."

Tuesday was the second busiest day for the lifeline this year. The most busy day was in late May, which is likely related to Memorial Day.