My dear lifelong friend lost her daughter to suicide. She died 10 days before her 20th birthday. Her entire life was burdened with mental illness and she struggled mightily to get through every day. Her parents worked night and day to save their child, but in the end it was for naught. She wasn't into drugs or alcohol and she didn't have a sudden life-changing tragedy occur prior to her death. She was, simply, mentally ill. It makes no sense but also makes plenty of sense. It's torture.
My son has Asperger's syndrome and has been labeled off and on throughout his life with various diagnoses from behavioral disorder NOS, bipolarism, ADD, ADHD, ODD, and schizophrenia. He's doing quite well now, much better than 3 years ago. I worry about him so much that at times I have panic attacks which I never had as a young person. You learn to live life 1 day at a time for sure. You focus all your energy on getting them through life and doing everything you can to keep them motivated about life because they can stop being motivated without warning.
I'm a medical transcriptionist and the number of people who come into the hospital on a daily basis for mental health and/or drug and alcohol issues is so staggering you don't even want to know about it.