A majority of Hamilton County high school students have used one or more addictive substances, but fewer than half say they are currently using, a recent survey shows.

About seven in 10 high schoolers who responded to the 2011 Youth Risk Behavior Survey have tried at alcohol, cigarettes, marijuana or cocaine. About 40 percent of responding students reported they had used one of these "addictive substances" in the past month.

Substance use among Hamilton County high-school students has decreased since the survey was first given in 1998. In that year, 84 percent of respondents said they had ever used one or more of the addictive substances and 55 percent said they had done so in the past month.

Rae Bond, executive director of the Chattanooga-Hamilton County Medical Society and Medical Foundation of Chattanooga and a member of the Regional Health Council, stressed the survey's importance in light of research showing that addictive substances can change the structure of teenagers' developing brains more quickly than they do in adult brains.

"I think it's especially critical for us to think about what our kids are doing ... to equip them for good decision-making as they age," Bond said.

In the 2011 survey, substance use varied by race, gender and age. Males were more likely than females to be current users, and substance use increased in each successive grade.

White students in the survey were more likely to be current users of alcohol, cigarettes and smokeless tobacco -- or to have ever used prescription drugs or inhalants -- than black or Latino students. However, black students were the most likely to be current marijuana users, according to the survey.

Alcohol was the substance students were most likely to use, with 32 percent of survey respondents saying they had drunk it in the past month. Eighteen percent of students engage in binge drinking -- defined as having five or more drinks within a few hours -- and students who drink are more than twice as likely to engage in binge drinking than adult drinkers.

"High school students drink to get drunk," said Ione Farrar, community health planner for the Chattanooga-Hamilton County Health Department, at a news conference Wednesday.

Fifteen percent of students said they have taken prescription drugs when they did not have a prescription. Thomas Miller, a physician who belongs to the Regional Health Council, said at the news conference that this statistic did not come as a surprise to him.

"It is the new kid on the block and it's a very dangerous kid on the block," Miller said.

Soddy-Daisy High School students who spoke at the news conference said parents should be the first people to speak to their children about the dangers of substance use.

"The programs really need to start at home," said Emily Woodard, a Soddy-Daisy senior.

Miller and the students also expressed their disappointment that the Students Taking A Right Stand program -- which works with schools to educate students about healthy decision-making -- had lost some of its funding.

STARS Executive Director Karen Glenn said in a phone interview that the organization had a grant eliminated two years ago that made up about 60 percent of its budget.

After the loss of money, STARS limited personnel and is less visible, she said. However, the program is still providing resources to schools and the schools are still providing drug and alcohol education, Glenn said.