Approximately 47 percent of the U.S. population reads below an eighth-grade level, but the percentage is significantly greater among people using public mental-health services, according to Alisa Lincoln, an associate professor of sociology and health sciences at Northeastern University.

In spite of this statistic, as well as a growing body of literature on the impact of reading ability on general health outcomes, scant research is available on the impact of limited literacy on mental health.

Lincoln, the interim director of Northeastern’s Institute for Urban Health Research, hopes to change that. She recently received a three-year, $1.3 million grant from the National Institute of Mental Health to explore the connection between literacy and mental health.

“You can’t approach this from just one discipline,” said Lincoln, who has joint appointments in the Bouvé College of Health Sciences and the College of Social Sciences and Humanities.

For example, she said, “As a sociologist, I don’t have the skills to assess cognitive functioning. I need a neuropsychologist to do that.”

Lincoln has assembled a team that comprises public-health experts, a medical anthropologist, two cognitive psychologists, a psychiatrist, two literacy specialists and a biostatistician.

Together, she said, the team will be better able to establish a comprehensive analysis of the impact of limited literacy on the mental health community.

The team first established limited literacy as a key factor in the lives of mental-health patients through a pilot study that surveyed a small group of patients. Those with higher reading abilities tended to use their skills in a variety of ways to navigate the healthcare system and cope with their symptoms. Several coping strategies were not accessible to patients with limited literacy, however, from searching the Internet for more information about their condition to journaling about their struggles.

With the grant funding, Lincoln’s team will expand its research study to include 300 people using public mental-health services in Boston. “They’ll be participating in structured interviews that will assess their levels of reading literacy, numeracy, and aural literacy, as well as many factors related to the social context of their lives,” Lincoln explained.

She noted the significant body of research focused on negative experiences caused by mental illness and the small but growing number of research studies on the shame associated with limited literacy.

“If you’re living with mental illness and struggling with limited literacy, you’re dealing with a double whammy,” Lincoln said. “It’s no wonder these folks are cut off from many societal resources.”

In addition to the practical parts of life that limited literacy inhibits — such as reading medication bottles or filling out forms — it may also feed into the symptoms of patients’ original conditions. “We know that the social stigma of mental illness worsens mental health,” Lincoln said. “We assume, and now will learn about, whether the shame and stigma associated with literacy problems does the same.”