Feb. 5 (HealthDay News) -- Direct exposure to the World Trade Center terrorist attacks boosted behavioral problems in preschoolers, new research shows.

The study, by researchers at the Mount Sinai School of Medicine in New York City, included 116 children averaging about 4 years of age who lived in or attended preschool in lower Manhattan at the time of the 2001 attacks.

Between March 2003 and December 2005, the researchers asked parents to provide information about the children, including their level of exposure to the attacks, exposure to other traumatic events (such as the death of a family member, seeing a serious accident, or being in a natural disaster), and emotional and behavioral details.

Of the children in the study, 23 percent were exposed to one or more high-intensity WTC events, such as seeing the towers collapse, seeing injured people or dead bodies, or witnessing people jumping out of the buildings.

The study found that children exposed to such events were nearly five times more likely to have trouble sleeping and almost three times more likely to be depressed and anxious than children who weren't exposed to the attacks.

The study also found that children who'd experienced the attacks and another traumatic event were 21 times more likely to have emotional problems or to be anxious or depressed, and 16 times more likely to have attention problems than children who hadn't experienced any kind of traumatic event.

The study appears in the February issue of the Archives of Pediatrics & Adolescent Medicine.

The researchers said the findings are consistent with an "allostatic load theory" of stress, which suggests that accumulated exposure to difficult events increases the risk of psychological effects.

"Physicians seeking to assess the impact of terrorism and disaster on very young children should assess for disaster-related exposure and for other trauma," the study authors wrote. "More vigorous outreach to trauma-exposed preschool children should become a post-disaster public health policy."

SOURCES: JAMA/Archives journals, news release, Feb. 4, 2008