Research from a joint American-Australian study has found that teen love feels life-changing because the combination of a developing brain, surging hormones and a lack of identity leads to adolescents ''merging'' so that they feel not quite whole when apart.

Psychologist Dr Carl Pickhardt from the American and Texas psychological associations, who led the study, said ''teen love'' was usually infatuation - different to the feeling of love experienced by adults - and was more moving for young people because it was a deeper relationship than any other they had experienced.

University of Canberra clinical psychologist Dr Vivienne Lewis, who specialises in treating teens, said it was not uncommon for adolescents to be referred to her practice with severe depression after a relationship of one month ended.

She said infatuation, which was what most teenagers experienced in a relationship, was a more consuming emotion than love.

''They are more infatuated and consumed by the situation, and that's why a breakup hurts so much, because they invest a lot in their relationship - a lot of themselves, much more than adults do. So, when it falls apart they are not like adults, they don't have other things to grasp on to,'' Dr Lewis said.

She said adults were better able to cope with breakups because they were more careful.

''Teens are being overwhelmed by the endorphins and hormones that are involved and because they aren't used to that experience they can be completely crushed when it breaks down. Adults have usually been through a few relationships so they are more careful.''

Dr Lewis said it was important for parents to try to understand what their children were feeling.

''Parents of adolescents need to understand that breaking up with someone is quite devastating because for them that is their whole life.''

She said children who had goals outside of their first relationships were more likely to recover from a painful high school breakup without developing depression.

''Parents need to keep children engaged in lots of other things - with their family, playing sport, doing school work - so the relationship is just one part of their life. It's when it becomes the sole part of their life that it becomes dangerous and when it breaks down could lead to mental-health issues.''