MODESTO —Topamax. Depakote. Phenobarbital. The list goes on. Before Jayden David turned 5, he had tried a dozen powerful medications to tame a rare form of epilepsy. The side effects were devastating.

There were grand mal seizures that lasted more than an hour. Hundreds of times a day, muscle twitches contorted his impish face.

"If he wasn't sleeping, he was seizing," said Jayden's father, Jason David.

PHOTOS: Treating son's epilepsy

Feeling helpless, David said, he contemplated suicide. He prayed. Then one day he heard about a teenager who was expelled from school for using marijuana to help control seizures.

So began the pair's journey into California's medical cannabis culture.

In the 14 months since, the little boy has been swallowing droppers full of a solution made mostly of cannabidiol, or CBD, the second most prominent of marijuana's 100 or so cannabinoids. Unlike the dominant THC, cannabidiol is not psychoactive, so the sweet-tasting infusion Jayden takes four times a day doesn't make him high.

Down from 22 prescription pills per day to four, he now eats solid food, responds to his father's incessant requests for kisses and dances in his Modesto living room to the "Yo Gabba Gabba!" theme song. The frequency and intensity of his seizures have been greatly reduced.

But this summer, federal prosecutors moved to close Oakland's Harborside Health Center — the nation's largest dispensary and the place David has relied on most for help.

The public debate over medical marijuana — which violates federal law but is legal in California, 17 other states and the District of Columbia — for the most part has pitted those who praise its health benefits against those who say it is merely an excuse to get high. Lost in the discussion has been the fact that marijuana has myriad components that affect the body in a number of ways.

CBD, for instance, was virtually bred out of U.S. plants decades ago by growers whose customers preferred the mind-altering properties of high-THC varietals. Yet it is experiencing a resurgence, having shown promise as an anti-inflammatory, anticonvulsant, neuroprotectant and cancer-fighting agent.

"Nobody is going to a dispensary for this to get high," said Martin Lee, a Bay Area writer who has reported on cannabidiol for years. "With CBD, it's clear that it's just about medicine."

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A photo in the kitchen shows a beaming David nuzzled up against his newborn son. But the family's joy soon clouded. Jayden had his first grand mal at 4 1/2 months. The muscle jerks followed, as did seizures that cause sudden collapse.

At 1 1/2, the blue-eyed boy was diagnosed with Dravet syndrome, a form of infant epilepsy described in medical literature as catastrophic — and potentially fatal.

David and Jayden's mother, whose marriage failed under the stress, consulted top experts, resulting in "more drugs and more ambulance trips," David said.

By late 2010, Jayden had tried 11 medications. The 12th was stiripentol, hailed as a potential Dravet breakthrough. But after six months, Jayden's seizures and side effects were worse. David said his son rarely responded to those around him, had difficulty chewing and often screamed in fear.

"I was going crazy," David said. The onetime jewelry store manager recalled stepping out onto his front lawn in April 2011 to make a phone call: "Mom," he said. "I'm going to shoot myself in the head. I can't stand seeing him this way."

That Sunday, David, a devout Assyrian Christian, and his girlfriend brought Jayden to their parish. "We were asking God for signs," David said.

The TV news story David saw the next day about the epileptic teenager seemed to offer one. Scouring the Internet, he came across decades of research documenting the therapeutic effects of CBD.