The adrenalin rush that comes with placing a wager is what keeps bettors betting — and problem gamblers losing. Donaghy, with his high-profile, $260,000-a-year job and beautiful Florida home, didn't need the money.

He needed the excitement.

"It's not about the money so much as the action," said Arnie Wexler, a recovering compulsive gambler who operates a hot line for people with the same addiction. "It makes you feel like a big shot by being in the action. ... The need for action drives you."

Donaghy pleaded guilty to federal charges last week, admitting he provided NBA betting picks to gambling associates based on inside information.

Donaghy, a married, 13-year veteran official with four daughters, acknowledged the "unique access" provided by his job — including which crews would officiate certain games, the relationships between certain officials and players, and the physical condition of certain players.

The 40-year-old Donaghy has battled gambling demons for several years.

While court papers say Donaghy himself bet on the NBA for four years, including games he officiated, compulsive gambling experts said taking payoffs for picks make perfect sense. There is a thrill that comes with every bet, whether it involves a neighborhood bookie or a lucrative tip slipped to a high-roller, they said.

Donaghy, surrounded by multimillionaire players and their opulent lifestyles, might have received a self-esteem boost by making himself a "player" in the gambling world, the addiction experts said.

Authorities did not specify any games where Donaghy officiated and placed bets, nor would they say if he made calls during games to help a team cover the spread. But court documents provided a glimpse of his scheme.

In one exchange with his coconspirators, court papers said, Donaghy provided a tip about an NBA game on Dec. 13, 2006. He officiated a Boston Celtics-76ers game in Philadelphia that same day.

The next day, Donaghy met with the conspirators to receive a cash payment for passing along useful information about the 76ers-Celtics game, said a person close to the investigation, speaking on condition of anonymity to The Associated Press because the case is ongoing.

The point spread moved two points before tip-off — a sizable swing — with Boston going from a 1.5-point favorite to a 3.5-point choice. Boston won by 20.

Speaking in code during telephone calls, Donaghy made gambling recommendations to the coconspirators. If he was correct, they paid him $5,000 in cash. If he was wrong, he received nothing.

Donaghy, who faces up to 25 years in prison at his sentencing, admitted in court last Wednesday that he was receiving treatment for a gambling addiction. He told the court he also was taking medication for depression and anxiety.

"He has had a severe gambling problem for a while that went untreated and unfortunately he did not get the proper care that was needed," Donaghy's attorney, John Lauro, said last week. "And now he is getting that care."

Most compulsive gamblers stay in denial, according to Dr. Mitchell Wallick, executive director of CARE, a gambling treatment center in Palm Beach, Fla.

"They think, 'I am wiser, I can beat the system, I'm really not gambling,"' Wallick said.

But gambling — even of the legal variety — is off-limits for NBA referees. They are not allowed to step foot in a casino, for example.

Still, there have been whispers about NBA referees and gambling.

A report on ESPN Radio in New York said Donaghy will provide prosecutors as many as 20 names of other NBA officials and will detail their involvement in some form of gambling, believed to include betting in casinos. NBA spokesman Tim Frank said the league had no additional information and would not comment.

Commissioner David Stern earlier said the NBA would "continue with our ongoing and thorough review of the league's officiating program to ensure that the best possible policies and procedures are in place to protect the integrity of the game." Stern said the scandal was the result of a "rogue, isolated criminal."

Wexler was not surprised Donaghy's addiction went untreated, since problem gamblers often leave no obvious trail.

"There are no dilated pupils, track marks, smells or empty bottles," Wexler said. "He can sit next to you all day long and do his shenanigans and you would never know he is a compulsive gambler until he gets arrested.