On a warm August morning in Harare, Farai, a 24-year-old mother of two, walks towards a park bench. She looks miserable and dejected. Now, on the park bench sits an 82-year-old woman, better known to the community as Grandmother Jack. Farai hands Grandmother Jack an envelope from the clinic nurse. Grandmother Jack invites Farai to sit down as she opens the envelope and reads. There's silence for three minutes or so as she reads. And after a long pause, Grandmother Jack takes a deep breath, looks at Farai and says, "I'm here for you. Would you like to share your story with me?" Farai begins, her eyes swelling with tears. She says, "Grandmother Jack, I'm HIV-positive. I've been living with HIV for the past four years. My husband left me a year ago. I have two kids under the age of five. I'm unemployed. I can hardly take care of my children." Tears are now flowing down her face. And in response, Grandmother Jack moves closer, puts her hand on Farai, and says, "Farai, it's OK to cry. You've been through a lot. Would you like to share more with me?" And Farai continues. "In the last three weeks, I have had recurrent thoughts of killing myself, taking my two children with me. I can't take it anymore. The clinic nurse sent me to see you." There's an exchange between the two, which lasts about 30 minutes. And finally, Grandmother Jack says, "Farai, it seems to me that you have all the symptoms of kufungisisa." The word "kufungisisa" opens up a floodgate of tears. So, kufungisisa is the local equivalent of depression in my country. It literally means "thinking too much." The World Health Organization estimates that more than 300 million people globally, today, suffer from depression, or what in my country we call kufungisisa. And the World Health Organization also tells us that every 40 seconds, someone somewhere in the world commits suicide because they are unhappy, largely due to depression or kufungisisa. And most of these deaths are occurring in low- and middle-income countries. In fact, the World Health Organization goes as far as to say that when you look at the age group between 15 to 29, a leading cause of death now is actually suicide. But there are wider events that lead to depression and in some cases, suicide, such as abuse, conflict, violence, isolation, loneliness -- the list is endless. But one thing that we do know is that depression can be treated and suicides averted. But the problem is we just don't have enough psychiatrists or psychologists in the world to do the job. In most low- and middle-income countries, for instance, the ratio of psychiatrists to the population is something like one for every one and a half million people, which literally means that 90 percent of the people needing mental health services will not get it. In my country, there are 12 psychiatrists, and I'm one of them, for a population of approximately 14 million. Now, let me just put that into context. One evening while I was at home, I get a call from the ER, or the emergency room, from a city which is some 200 kilometers away from where I live. And the ER doctor says, "One of your patients, someone you treated four months ago, has just taken an overdose, and they are in the ER department. Hemodynamically, they seem to be OK, but they will need neuropsychiatric evaluation." Now, I obviously can't get into my car in the middle of the night and drive 200 kilometers. So as best as we could, over the phone with the ER doctor, we come up with an assessment. We ensure that suicidal observations are in place. We ensure that we start reviewing the antidepressants that this patient has been taking, and we finally conclude that as soon as Erica -- that was her name, 26-year-old -- as soon as Erica is ready to be released from the ER, she should come directly to me with her mother, and I will evaluate and establish what can be done. And we assumed that that would take about a week. A week passes. Three weeks pass. No Erica. And one day I get a call from Erica's mother, and she says, "Erica committed suicide three days ago. She hanged herself from the mango tree in the family garden." Now, almost like a knee-jerk reaction, I couldn't help but ask, "But why didn't you come to Harare, where I live? We had agreed that as soon as you're released from the ER, you will come to me." Her response was brief. "We didn't have the 15 dollars bus fare to come to Harare." Now, suicide is not an unusual event in the world of mental health. But there was something about Erica's death that struck me at the core of my very being. That statement from Erica's mother: "We didn't have 15 dollars bus fare to come to you," made me realize that it just wasn't going to work, me expecting people to come to me. And I got into this state of soul-searching, trying to really discover my role as a psychiatrist in Africa. And after considerable consultation and soul-searching, talking to colleagues, friends and family, it suddenly dawned on me that actually, one the most reliable resources we have in Africa are grandmothers. Yes, grandmothers. And I thought, grandmothers are in every community. There are hundreds of them. And -- (Laughter) And they don't leave their communities in search of greener pastures. (Laughter) See, the only time they leave is when they go to a greener pasture called heaven. (Laughter) So I thought, how about training grandmothers in evidence-based talk therapy, which they can deliver on a bench? Empower them with the skills to listen, to show empathy, all of that rooted in cognitive behavioral therapy; empower them with the skills to provide behavior activation, activity scheduling; and support them using digital technology. You know, mobile phone technology. Pretty much everyone in Africa has a mobile phone today. So in 2006, I started my first group of grandmothers. (Applause) Thank you. (Applause) Today, there are hundreds of grandmothers who are working in more than 70 communities. And in the last year alone, more than 30,000 people received treatment on the Friendship Bench from a grandmother in a community in Zimbabwe. (Applause) And recently, we published this work that is done by these grandmothers in the Journal of the American Medical Association. And -- (Applause) And our results show that six months after receiving treatment from a grandmother, people were still symptom-free: no depression, suicidal ideation completely reduced. In fact, our results -- this was a clinical trial -- in fact, this clinical trial showed that grandmothers were more effective at treating depression than doctors and -- (Laughter) (Applause) And so, we're now working towards expanding this program. There are more than 600 million people currently aged above 65 in the world. And by the year 2050, there will be 1.5 billion people aged 65 and above. Imagine if we could create a global network of grandmothers in every major city in the world, who are trained in evidence-based talk therapy, supported through digital platforms, networked. And they will make a difference in communities. They will reduce the treatment gap for mental, neurological and substance-use disorders. Finally, this is a file photograph of Grandmother Jack. So, Farai had six sessions on the bench with Grandmother Jack. Today, Farai is employed. She has her two children at school. And as for Grandmother Jack, one morning in February, we expected her to see her 257th client on the bench. She didn't show up. She had gone to a greener pasture called heaven. But I believe that Grandmother Jack, from up there, she's cheering on all the other grandmothers -- the increasing number of grandmothers who are making a difference in the lives of thousands of people. And I'm sure she's in awe when she realizes that something that she helped to pioneer is now spreading to other countries, like Malawi, the island of Zanzibar and coming closer to home here in the Unites States in the city of New York. May her soul rest in peace. Thank you. (Applause) (Cheering) (Applause)