“We never thought that would happen to us,” Dr. Pean said.

‘I’m Manic!’

In his family of high-achievers, Alan Pean (pronounced PAY-on) is the soft-spoken and mellow middle sibling, into yoga, video games and pickup football. Christian, 28, now a medical student at Mount Sinai in New York, is the Type A leader; Dominique, 24, is following his path, applying to medical school while pursuing a master’s degree. Alan, who had never been in any sort of trouble, is “probably the nicest of us three,” Dominique said.

Like many people with mental health issues, he did not get a clear-cut diagnosis. After a brief delusional episode in 2008, he was hospitalized for a more severe recurrence the next year, at the end of his second year at the University of Texas. He was kept for a week and told that he had possible bipolar disorder, though his symptoms did not reappear for years even after he tapered off medication.

He was prone to bouts of sadness and anxiety, he recalled in an interview, but had attended college, taking breaks from time to time, and worked for a while as a medical assistant back home in McAllen, near the Mexican border. Though he had smoked marijuana regularly to help tame his symptoms, he said in an interview, he quit last summer when he enrolled at the University of Houston to complete his bachelor’s degree.

Just days into the semester, though, he barely slept and found himself increasingly agitated and delusional.

On Aug. 26, he talked repeatedly on the phone with his parents and brothers, who tried to calm him but worried that he sounded disoriented. Christian had been concerned enough that he called the Houston police to do a “welfare check” on his brother at his apartment, though no one answered the door when officers arrived.

When Mr. Pean sounded worse in the evening, his family summoned a fraternity brother in Houston to take him to an emergency room; his parents would fly in the next morning. But Mr. Pean did not wait. His mind vacillating between the knowledge that he needed psychiatric medication and encroaching delusions that he was a Barack Obama impersonator or a “Cyborg robot agent” who was being pursued by assassins, he said, he got into his white Lexus and drove at high speed to St. Joseph Medical Center, the only major hospital in downtown Houston.

Turning into the parking lot just before midnight, he crashed, nearly totaling his vehicle. As Mr. Pean was helped into the emergency room and onto a stretcher by paramedics and nurses, he recalled, he yelled: “I’m manic! I’m manic!”