(CNN) -- Jason Russell, who directed a documentary about a notorious Ugandan warlord that went viral, will remain hospitalized "a number of weeks" to recover from "reactive psychosis," his family said Wednesday.
Russell, 33, was picked up by police last Thursday after several people reported a man running along a San Diego, California, street in his underwear, screaming, sources said.
"Jason's incident was in no way the result of drugs or alcohol in his body," the family statement said. "The preliminary diagnosis he received is called brief reactive psychosis, an acute state brought on by extreme exhaustion, stress and dehydration."
Russell's family said his doctors told them it was "a common experience given the great mental, emotional and physical shock his body has gone through in these last two weeks."
"Even for us, it's hard to understand the sudden transition from relative anonymity to worldwide attention -- both raves and ridicules, in a matter of days," their statement said.
The filmmaker "has a long way to go, but we are confident that he will make a full recovery," his family said.
"He is, and will remain, under hospital care for a number of weeks; and after that, the recovery process could take months before he is fully able to step back into his role with Invisible Children," it said. "During that time, we will focus not on a speedy recovery, but a thorough one."
Russell is one of the founders of the San Diego-based nonprofit group Invisible Children, which produced the half-hour film about warlord Joseph Kony. "Kony 2012" skyrocketed to popularity on YouTube, propelled by thousands of posts on Twitter and Facebook, garnering nearly 85 million views since its March 5 release.
The popularity of the film led to a flurry of media appearances for Russell and his fellow Invisible Children co-founders and prompted scrutiny from some who argued that the social media frenzy was too little, too late.
The group has said it hopes the film and other efforts will make Kony a household name and drum up international support to halt the killings, rapes, abuses and abductions committed by his group, the Lord's Resistance Army, in central Africa.
Kony, who has operated in central Africa for two decades, is wanted for crimes against humanity by the International Criminal Court. In October, the United States sent 100 combat-equipped troops on a mission to kill or capture Kony.
"We thought a few thousand people would see the film, but in less than a week, millions of people around the world saw it. While that attention was great for raising awareness about Joseph Kony, it also brought a lot of attention to Jason -- and, because of how personal the film is, many of the attacks against it were also very personal, and Jason took them very hard," the statement said.
Ben Keesey, the group's chief executive, issued a statement Friday confirming that Russell was hospitalized for "exhaustion, dehydration and malnutrition."
"The past two weeks have taken a severe emotional toll on all of us, Jason especially, and that toll manifested itself in an unfortunate incident yesterday," Keesey said.
CNN's Rachel Wells contributed to this report.