Dr. McFarlane, the former director of the PIER Training Institute in Portland who tutors personnel at PIER sites around the country, has noted that about 20 percent of all hospital admissions and disability payments are for patients with severe mental illness, mostly schizophrenia and other psychotic disorders. These ailments also shorten life by an average of 25 years.

“When you develop severe mental illness, you are driving off a cliff,” the psychiatrist said. “Imagine if you could stop a process that’s already underway.”

Psychosis, which is not a disease but a symptom of a brain illness, usually begins in late adolescence and young adulthood. The causes are not known. The disorder, which is genetically complex, tends to run in families — more than 100 genes have been linked to schizophrenia, for example. Its onset is often precipitated by episodes of intense stress or severe chronic stress.

There are many possible signs that someone is at risk of developing a psychotic break, but too often they are often dismissed as symptoms of typical adolescent behavior, experts say. Psychosis rarely comes on suddenly. Rather, the person gradually experiences changes in thoughts and perception, making it difficult for the person to recognize what is real and what is not, the National Alliance on Mental Illness (NAMI) points out.

The alliance lists these early warning signs:

A worrisome drop in grades or job performance

Trouble thinking clearly or concentrating

Suspiciousness or uneasiness with others

A decline in self-care or personal hygiene

Spending a lot more time alone than usual

Strong, inappropriate emotions or having no feelings at all

The person may hear, see or believe things that others do not; experience distracting sensations; be confused about what is real and what is not; and become mistrustful or even panicky.

Ms. Martinez recalled that she began to hear voices, see shadowy figures and have troubling, intrusive thoughts. “I would walk out into the courtyard outside my dorm and for some reason I had this thought to be careful of the trees because they were going to collapse on me,” she reported.

A number of studies in recent decades have shown that first episodes of psychosis can be prevented through early detection and treatment, as shown by a Dutch team in a 2013 meta-analysis of randomized controlled trials.