NEW YORK (Reuters) - In good news to parents of late talkers, an Australian study shows a slow start on language is unlikely to have lingering effects on kids mental health. Researchers followed late talkers into their teens and found the kids were no more likely to be shy, depressed or aggressive than their peers as they grew up. That means a wait-and-see approach may be just fine for toddlers with a language lag, as long as they develop typically in other areas, the Australian team reports in the journal Pediatrics. This data is reassuring, said Julia Irwin, who studies language development at Haskins Laboratories, a non-profit research institute in New Haven, Connecticut. But parents will need to pay attention to other troubling symptoms of either psychosocial problems or language and reading problems. In an email to Reuters Health, Irwin said late talkers often have some language or reading problems later on, which may influence school readiness. Between seven percent and 18 percent of children have language delays at two years, although most catch up by the time they start school. Some research has suggested that these toddlers may face psychological problems, but whether that matters down the road has been unclear. The new study, led by psychologist Andrew Whitehouse at the University of Western Australia in Perth, is the first to track late talkers over the long haul. The researchers tapped into data on more than 1,400 two-year-olds, whose parents had filled out a language development survey asking about the words their child would use spontaneously. A two-year-old typically says a few hundred words, but there is a lot of variation. About one out of every 10 two-year-olds in the study was a late talker, scoring in the lowest 15 percent on a list of 310 common words. The slower toddlers also appeared to have more psychological problems, according to questions on a child behaviour checklist that parents answered. For instance, 13 percent of the late talkers had internalizing behavior such as being shy, sad or underactive compared to eight percent of their faster-talking peers. But that difference had vanished at age five, when then parents were approached again. And it didnt reappear for as long as the kids were followed, up until age 17. 'Wait and see may be okay at 2 years, but there should be a critical time after which language delays should be treated, said child psychologist Gail Ross, adding that age two-and-a-half or three might be appropriate. Between seven percent and 18 percent of children have language delays at two years, although most catch up by the time they start school. Some research has suggested that these toddlers may face psychological problems, but whether that matters down the road has been unclear.