I am frequently asked, "How could you not know your son had a serious mental illness? You're a nurse!" Yes, I am ashamed that I did not know. Yes, I am horrified that my son, James Holmes, walked into a movie theater and murdered 12 people and seriously injured dozens of others. Yes, I am a registered nurse.

I never thought my son was one of the millions who have serious mental illness. That's because he functioned very well . . . until he didn't. He had a psychotic episode, and turned to violence, later telling the court-appointed psychiatrist that he thought killing people would increase his worth as a human being. I am deeply sorry that I did not recognize the early signs of serious mental illness and get him treated. I apologize to the victims of the shooting and their friends and family members. I know they suffer physically and mentally, and I wish I had the power to turn back time, to prevent this tragedy, to erase the pain.

Why wouldn't a nurse know her own son was exhibiting signs of schizophrenia? I envisioned someone with severe mental illness as hospitalized or on the streets, nonfunctional or exhibiting extreme agitation. But I never worked as a behavioral health nurse and took no continuing education courses about psychiatric conditions.

And I also did not think about children having mental illness. My son was a physically healthy, happy little boy who liked to play with other kids and performed well in school. He never displayed signs of violence, talked about his anxiety, or balked at going to school.

According to the National Institute of Mental Health, signs of a lifelong mental health disorder occur before the age of 14 in 50% of cases, and two-thirds of young people with mental health problems are not receiving the help they need. In my son's case, social withdrawal increased around the time of early puberty, when parents expect their children may change and become irritable and more private. I took him to a social worker, who never talked to my son alone and made no referrals. In retrospect, I should have taken him to a child psychologist. But he did have many moments when he enjoyed the company of his family and close friends. He was not eating lunch alone at school; he was not bullied. His shyness did not stand out in our family of introverts. And he was a teacher's dream: a quiet kid who does his homework and causes no trouble.

Only later at the trial did we learn through the testimony of a high school coach that my son found it hard to be near or make eye contact with other students, an observation she never relayed to me or to the school counselor. My son never told us how anxious he became around other people. Our family culture emphasized hard work, no complaining, and "toughing it out," an approach I now know to have been detrimental.

Though he kept to himself during college, he obtained a bachelor's degree in neuroscience. He moved home for a year afterward and seemed tired, unmotivated. He was unexpressive and moved slowly. His behavior was consistent with the negative symptoms of schizophrenia: blunt affect, alogia, apathy, anhedonia. The term negative symptoms refers to diminished or absent thoughts, feelings, or behaviors that are normally present. By contrast, the positive symptoms of schizophrenia stand out because they are thoughts and behaviors not seen in healthy people, including delusions, hallucinations, and abnormal movements.

My son moved 1,000 miles away to go to graduate school, where he was required to interact with students in his labs and carried a heavy load of schoolwork. We had no idea that he'd begun failing his courses and isolating himself. He saw the university psychiatrist and told her he was disturbed by thoughts of killing people. Although she later testified in court that she thought he was floridly psychotic, she decided he did not need involuntary hospitalization. Two court-appointed psychiatrists and the defense psychiatrist later testified that my son had a diagnosis along the schizophrenia spectrum.

After he was incarcerated, he told me that he didn't feel it would be acceptable to tell me his thoughts-of "nuclear winter" and intense social anxiety when younger, and then, at graduate school, of killing people. In response, I told him that I would advocate for increased awareness of the signs of mental illness by discussing his symptoms. I feel strongly that every nurse in every discipline must understand the early symptoms and manifestations of brain disorders in order to improve detection and treatment. Furthermore, many nurses are parents, and all parents must keep informed.

Now I know . . . too late to help my son, too late to stop the deaths and injuries-but not too late to encourage other nurses to educate themselves.