John Nikolakis came from a privileged fami

题目：

John Nikolakis came from a privileged family. Few would have predicted that last September, at the age of 36, he would be alone in a dark, cold Louisiana apartment--all the utilities were cut off because he couldn’t pay for them--dead broke and writing suicide notes. He was on probation (缓刑) for having embezzled nearly $ 80,000 from his former employer. His entire adult life had been consumed by the intoxication and compulsion of gambling away hundreds of thousands of dollars on everything from online poker to sports. He lost two good jobs, one girlfriend, and 17 years of his life. "This gambling crap has cost me everything," he says. "It cost me my pride, my honesty, and the biggest thing it cost was the relationships of people who cared for me."
His story, with as many variations as there are individuals, illustrates the trajectory of most pathological (病理的) gamblers: a period of exhilaration and great windfalls--punctuated by a little dishonesty here and there--ending in misery, financial ruin, and shattered personal relationships. In 1980, the American Psychiatric Association officially categorized pathological gambling as a diagnosable medical disorder, and since then there has been increasing understanding of the brain chemistry, the biology, even the genetics that play a role. As pathological gambling has become more fully understood as a discrete disorder, more-sophisticated treatments have evolved. But pathological gambling has its own distinct pathology, so there are new and promising drug and therapeutic interventions as well.
Experts often describe pathological gambling as being both a "pure" and a "hidden" addiction. It is pure because it does not change the brain chemistry by introducing other substances like drugs or alcohol do. It is hidden because unlike, say, mainlining heroin, gambling is generally a socially acceptable behavior.
Socially acceptable behavior run am0k, that is, the pathological gambler needs to wager more and more money to achieve that deeply satisfying, and addictive, point of excitement. These indicate the difference between the person who takes an occasional trip to Atlantic City and someone with a real problem. And withdrawal can be punishing, with terrible headaches, irritability, and anxiety.
Experts say that pathological gambling is a problem that affects 11 million people--with 1.6 percent of adults being pathological gamblers arid an additional 3.9 percent suffering from problem gambling--and merits far greater attention than it has received. "People think it is poor character, bad willpower, someone is flawed in terms of moral strength," says Jon Grant, assistant professor of psychiatry at Brown Medical School and coauthor of Stop Me Because I Can’t Stop Myself. "Many people don’t have a clue that this is a biological illness with a distinct pathophysiology."
Scientists are learning that the brain arid even the genes of a pathological gambler differ from those of the occasional poker player. In research presented last month at the American Academy of Neurology’s annual meeting, scientists pointed to the prefrontal cortex (前额皮质), that part of the brain responsible for decision making and impulse control, as being impaired in pathological gamblers.
Dopamine--a neurotransmitter in a brain that acts like adrenaline (肾上腺素) and has lots to do with how people behave and experience pleasure--is also thought to be involved. When dopamine is released, the dopamine receptors act like magnets, telling it where to go. For pathological gamblers, the receptor sites in the midbrain that are driven by the anticipation of rewards are especially sensitive, requiring increasing amounts of dopamine to create the rush of happiness. What triggers the dopamine rush Gambling, of course, and a vicious cycle is created.

The story of John Nikolakis is presented to ______.

A．explain what is pathological gambling

B．show how miserable the gambler is

C．illustrate the path of a pathological gambler

D．warn people away from gambling