Falling grades. Symptoms of depression.

These are some of the changes some teens whose parents have been deployed for military service reported to researchers at Virginia Tech, according to a study released last week.

But adolescents also display a great deal of resiliency and are able to adapt to additional responsibilities after a parent is deployed, the study found.

"Teens seemed to be struggling to find a balance between wanting to talk about what was happening and wanting to be distracted from it," Jay Mancini, a professor of human development at Virginia Tech, said in a news release.

The study is the first of its kind to solicit direct responses from adolescents whose parents have been deployed. About 25 percent of the youths, or about 300,000 teens whose parents are deployed, are ages 12 to 18, according to the study.

Researchers conducted focus groups of 107 young people with a deployed parent at summer camps the teens attended in Virginia, Hawaii, Georgia, Washington and Texas.

The study was funded by a grant from the Military Family Research Institute at Purdue University and supported by the U.S. Department of Defense.

"While several participants mentioned that their relationship with the at-home parent improved because they could spend more time together, many others described the parent as 'stressed out' and less available due to other responsibilities and concerns," Mancini said.

The researchers also found that the reunion between parent and child was more difficult the longer the parent had been away.

"Teens can mature a great deal in a matter of 12 to 18 months," said Angela Huebner, an associate professor of human development at Virginia Tech. "The returning parent often treats them as if they were of the same age and maturity level as when the parent left."