Mario Della Grotta, the Cranston man who became the first American to undergo brain surgery for obsessive-compulsive disorder, died Monday night in Rhode Island Hospital. He was 40.

Della Grotta died of an illness that was not related to either his psychiatric disorder or his brain surgery, according to his psychiatrist, Dr. Benjamin D. Greenberg, of Butler Hospital. Della Grotta’s wife, Sheri, said he fell ill on Dec. 27 and had been in the hospital until his death.

In February 2001, Della Grotta became the first person in the United States to have electrodes implanted in his brain for the purpose of controlling OCD, in a procedure called deep brain stimulation.

The experimental surgery, performed at Rhode Island Hospital with Butler Hospital researchers, was an attempt to quiet the malfunctioning brain circuitry that underlay his extremely severe and disabling OCD.

People with OCD have irrational fears or repetitive thoughts, which they seek to calm with compulsive acts or rituals. Della Grotta’s OCD, at its height, filled his every waking hour with obsessions and rituals, including cleaning, ordering, counting and calculating.

After the surgery, Della Grotta gradually started responding to behavioral therapy. Within a few years, his obsessions were taking up about 5 hours a day instead of 18. He graduated from college and found a job. He also frequently gave talks to professionals and others about OCD and the effects of deep brain stimulation.

He was the subject of a Providence Journal story, “Prisoner of His Thoughts,” in December 2006. ( www.projo.com/extra/2006/ocd)

Since then, Greenberg said, Della Grotta continued to improve and began working on a memoir. He was “an active father” to his two young daughters –– Kaleigh, 7, and Nadia, who will turn 4 on Saturday.

“He just loved his family, his kids,” Sheri Della Grotta said.

Greenberg said that Della Grotta “encountered some discrimination in trying to get back into the work force, but nevertheless he’s held several jobs.”

Last year, Della Grotta spoke at the Frontiers of Science conference at Brown University and traveled to Washington, D.C., to address a symposium on “Brain Pacemakers” held by the U.S. Department of Health and Human Services.

“He was someone who had tremendous drive and persistence and strength of purpose,” Greenberg said.

“I mean, he never gave up. That was inspiring to everyone –– people at this hospital and other patients.”

Meanwhile, Greenberg is continuing to study deep brain stimulation to treat OCD, with a new clinical trial that gets under way next week.

At the request of Della Grotta’s family, a fund is being established to support OCD research at Butler Hospital. Checks can be sent to the Mario Della Grotta Memorial OCD Research Fund, Funds Development (attn: Michele R. Berard), Butler Hospital, 345 Blackstone Blvd., Providence, RI 02906.

ffreyer@projo.com