The ad showed rolled-up money, a credit card and two lines of cocaine.
If that didn't grab the reader's attention, the offer of up to $1,275 in compensation might.
In addition to running the ad in a weekly newspaper, the University of Pittsburgh's Psychiatric Molecular Imaging Program recently turned to Craigslist to find cocaine users for a new study.
The recruitment efforts -- and ways in which participants were managed during the study -- highlighted the challenges facing researchers in sensitive fields.
Researchers must find a sufficient number of the right kinds of subjects. They must get subjects to open up about matters such as alcohol use, illegal drug use and sexual practices. They must advance science without doing harm -- or giving participants ways to harm themselves.
Rajesh Narendran, an associate professor at University of Pittsburgh's department of radiology and psychiatry, ran the newspaper and Craigslist ads for a small study comparing brain scans of cocaine users with scans of participants who don't use any drugs. He's particularly interested in how levels of neurotransmitters may differ from one group to another, information that he said could help develop treatments.
He said the underlying question is, "How do we get them clean?"
Dr. Narendran said the ads helped him target his desired demographic -- men and women between 18 and 40 years old -- and reach an applicant pool of sufficient depth.
He and Jennifer Paris, intake and research program coordinator for Comprehensive Recovery Services at UPMC, may discount more than a dozen people for every one they accept into a study. Often, Dr. Narendran said, prospective participants are rejected because they have medical problems or take prescription medications that could influence the study.
While the ad sought "cocaine users," Dr. Narendran intended to get them clean.
He said participants -- only six cocaine users were needed -- had to abstain from drugs and alcohol for at least two weeks before the brain scans. Their abstinence was verified through blood and urine tests. After the brain scans, the participants were connected to drug and alcohol services.
He said the recently completed brain scans will be used to leverage federal funding for a bigger project.
Researchers routinely use ads, social media, websites and databases of volunteers to find study subjects. Sometimes, researchers struggle to find subjects. In other cases, they don't.
Although it asks people to reveal details about the most intimate aspects of their lives, the Kinsey Institute for Research in Sex, Gender and Reproduction has little difficulty finding participants for studies, spokeswoman Jennifer Bass said. That's true even though some subjects -- such as a group of women in Greenland the institute recently asked to collect daily saliva samples for a month -- have to make a considerable commitment to a project.
A nonjudgmental approach and pledges of confidentiality enable participants to open up, Ms. Bass said.
The institute, based in Bloomington, Ind., offers compensation that varies with the time and effort participants must invest in a given study. "But I think, generally, many people who participate in research want to contribute to scientific knowledge. It's exciting to be a part of that," Ms. Bass said.
She said some subjects, such as participants in drug trials, are seeking improvements in their own lives.
While Dr. Narendran offered up to $1,250 in compensation, he said the amount isn't as munificent as it may seem. Subjects had to make multiple visits to the research site and stay for hours at a stretch. The participants' work was over in a couple of weeks.
But some studies require years of participation. In those cases, researchers may send birthday cards or newsletters to participants or find other ways to keep them engaged, said Christopher Ryan, director of Pitt's institutional review board, which approves research proposals.
Mr. Ryan said he has been involved in a diabetes study that began in 1982 with about 1,440 participants. Today, he said, it still has more than 1,000.
Before beginning a project, university researchers routinely submit proposals to institutional review boards, which determine whether a study has scientific merit, is coherently structured and would do no harm to human subjects. Even so, some projects yield controversy.
A faculty member at King's College London recently attracted criticism with an email seeking participants for a study that will require them to use cocaine.
"This is an important scientific study to investigate how cocaine and its metabolites are spread through the human body. All the relevant ethical approvals were received for this study. The study will be conducted under the highest level of medical supervision," said a statement provided by college spokeswoman Katherine Barnes.
Mr. Ryan said he could recall no study at Pitt that required ingestion of illegal narcotics.
The level of compensation -- and how study subjects might use that compensation -- is one issue considered by researchers and reviewers. If it's believed that drug users will use money to purchase drugs, researchers might consider alternative compensation, such as grocery store gift cards, said Karen E. Moe, director of the human subjects division, assistant vice provost for research and associate research professor of psychiatry and behavioral sciences at the University of Washington.
"It's definitely something we discuss," she said.
Mr. Ryan said studies have shown that drug users usually don't spend research money on narcotics. In fact, he said they're more likely to spend it on food. "The data are pretty compelling," he said.
Dr. Narendran said some cocaine users have dropped out of his studies because they can't stay clean. In those cases, he wrote in an email, "we counsel them and link them with addiction treatment programs so they can work on abstinence."
Joe Smydo: firstname.lastname@example.org or 412-263-1548.