Educators have long touted the benefits of offering college courses in high school: they help more students get into college and speed them on their way to a degree so they can save on tuition. But a new Texas study suggests those benefits may be inflated.

The study, released Thursday, showed some positive effects of taking the college classes — known as dual credit courses — but they tended to benefit more academically-prepared students in higher-income households. Students from low-income households who were not already excelling academically did not benefit as much from the courses, according to the study.

“It’s not surprising. I’ve been wary of the claim among some that dual credit is a magic bullet. It’s not,” said Raymund Paredes, the Texas commissioner of higher education. “If students are not college ready, it’s an open question if they should be in dual credit to begin with.”

Researchers looked at data from 16 cohorts of Texas high school juniors from 2001 to 2016 for the study, conducted for the Texas Higher Education Coordinating Board. Participation rates were higher for white students. For all who took dual credit courses, the college enrollment rate was about 2.4 percentage points higher than those who did not enroll in dual credit. College completion rates for both two-year and four-year degrees were about 1.1 percentage points higher.

The study also found that students enrolled in dual credit courses finished college about a month sooner than their peers — the equivalent of one summer term.

“They are good for low-income students, if the students are college ready,” Paredes said. “Access without preparation is not opportunity. If students are not prepared academically to do college level work, it can backfire.”

Dual credit courses were originally designed to give high-achieving students more challenging work. But high schools around the country have enrolled students with varying academic backgrounds into the courses, arguing that more rigor leads to better outcomes. In Texas, the number of students enrolled in dual credit courses has drastically increased. In 2000, there were about 18,500 and by 2016, more than 200,000.

The study suggested the courses themselves can be less rigorous than a comparable course in college, given a lack of uniform standards for dual credit courses across the state.

About 12,500 students enrolled last academic year in dual credit courses through one of the five community colleges in the Alamo Colleges District - a 42 percent increase since 2012. Dual credit last year made up one-fifth of the community college district’s total enrollment, and the cost of the free programs was one reason the district will increase tuition starting in January.

Texas A&M University-San Antonio’s partnerships with school districts will see just 34 dual-credit students taking courses at the university in the fall semester: 28 through a new program with the Southwest Prep charter network, and six in an arrangement with Three Rivers High School that began last year, said Briana Hagelgans, the university’s director of access.

The school districts pay TAMUSA a discounted tuition rate of $200 per course per student, and the high schools pay for the textbooks, she said.

“The reason it’s so small is because we’re a growing institution and we wanted to keep a good balance of early college high school students and traditional students,” Hagelgans said. “We wanted this population to grow as our institution grows.”

The researchers with the American Institutes for Research are gathering public input on their findings through the end of August. They intend to present policy recommendations to the coordinating board in October.

Staff Writer Alia Malik contributed to this report. | Alejandra Matos covers politics, immigration and education policy. | Alejandra.Matos@chron.com.