Trauma refers to a normal response to an abnormal event. About 14% of the children exposed to a trauma develop PTSD. The probability of developing PTSD increase the longer and more severe the traumatic events are.

PTSD includes several symptoms:

• Intrusion symptoms (e.g. nightmares; flashbacks)
• Avoidance behaviour
• Negative alterations in cognitions and mood (e.g. the world is unsafe)
• Alterations in arousal and reactivity (e.g. poor concentration)

The symptoms need to last for at least a month. For late-onset PTSD, the symptoms need to have an onset of 6 months after the traumatic event. The intrusion symptoms in children are represented in pretend play (e.g. playing the traumatic experience). Regressive behaviour (e.g. going back a developmental step) is common in children with PTSD.

There are several risk factors to develop PTSD:

• Direct exposure to life threats.

For a personality disorder to be diagnosed in adolescence, the problems have to be present for a year. There are four main areas of deficit:

• Affective dysregulation
• Impulsivity
• Instable relationships
• Identity problems

There are several symptoms of borderline personality disorder (BPD):

• Chronic feelings of emptiness.
• Emotional instability in reaction to-day events (e.g. intense episodic sadness) usually lasting a few hours and only rarely more than a few days.
• Frantic efforts to avoid real or imagined abandonment.
• Identity disturbance with markedly or persistently unstable self-image or sense of self.
• Impulsive behaviour in at least to areas that are self-damaging (e.g. spending; sex; substance abuse; reckless driving; binge eating).
• Inappropriate or intense anger or difficulty controlling anger.
• Pattern of unstable and intense interpersonal relationships characterized by extremes between idealization and devaluation.
• Recurrent suicidal behaviour,

Adolescents with externalizing problems tend to come from families where parental monitoring and control is lacking (i.e. under controlled). Externalizing problems are more common among males than females. Risk behaviour refers to behaviours that involve the risk of negative outcomes (e.g. substance use). Problem behaviour refers to behaviour that is viewed as a source of problems (e.g. unprotected sex).

People with externalizing problems often do not experience distress. Externalizing behaviours may be a manifestation of problems with family, friends or school but this need not be the case. It is often not motivated by unhappiness or psychopathology but by desire for excitement and intense experiences.

Driving is the number one source of death in adolescence and emerging adulthood in developed countries. Accidents are especially high in the first few months of driving but fall after having a license for more than a year. This

During adolescence and emerging adulthood, the emotional centre of people’s lives shift from their immediate families to people outside of the family (i.e. friends). Friends provide a bridge between the close attachment to family members and the close attachments of a romantic partner.

Peers refer to people who have certain aspects of their status in common (e.g. both playing the same sport; both approximately the same age). Peers become more important during adolescence across cultures, although gender differences in adolescent relationships are more pronounced in traditional cultures. However, compared to Western culture, more time is spent with the family.

In adolescence, time spent with same-sex friends remains stable and time with other-sex friends increases. The relationships with family and friends during adolescence change in both quantity and quality. Adolescents start to depend more on friends than on parents or siblings for companionship and intimacy. Parents