New York, Feb 21 (IANS) Adolescents suffering from trauma and stress are likely to have impairment in the ability to recognise facial expressions that is critical for social functioning and communicating emotions, researchers say.The findings showed that adolescents with post-traumatic stress disorder (PTSD) symptoms are more likely to misidentify sad and angry faces as fearful."Our findings suggest that exposure to stress and trauma can have acute emotional impacts that simply translate to misidentification of important affective cues," said lead author Shabnam Javdani, Assistant Professor at New York University - Steinhardt in the US."Fear is particularly relevant for understanding PTSD, as the disorder has been associated with a 'survival mode' of functioning characterised by an overactive fight-or-flight response and increased threat perception," Javdani added.In contrast, teens with conduct disorder -- a group of behavioural and emotional problems characterised by callousness or aggression towards others -- were more likely to misidentify sad faces, but did not have trouble recognising angry or fearful faces. Conduct disorder symptoms were associated with mistaking sadness for anger, suggesting that youth with higher levels of conduct disorder interpret sad faces as angry and may be less effective at recognising others' sadness, pain and suffering."Difficulty interpreting displays of sadness and misidentifying sadness as anger may contribute to the impaired affective bonding, low empathy, and callous behaviour observed in teens with conduct disorder," Javdani said.For the study, published in the journal Child and Adolescent Mental Health, the team examined 371 teens, ages 13-19, to understand the effects of PTSD and conduct disorder symptoms on how youth with emotional and behaviour problems process facial expressions. Enhancing the accuracy of recognising facial expressions may be an important treatment goal for youth with symptoms of PTSD and conduct disorder, the researchers said.