A depressed mood refers to an enduring period of sadness without any related symptoms. About 35% of adolescents report a depressed mood within the past six months. To receive a diagnosis of major depressive disorder (MDD), at least five of the following symptoms need to be present during a 2-week period, and must represent a change from previous functioning:

• • • • Depressed or irritable mood for most of the day, nearly every day.
      • Reduced interest or pleasure in all or almost all activities, nearly every day.
      • Significant weight loss or gain, or decrease in appetite.
      • Insomnia or oversleeping.
      • Psychomotor agitation or retardation, observable by others.
      • Low energy or fatigue.
      • Feelings of worthlessness or inappropriate guilt.
      • Diminished ability to think or concentrate.
      • Recurrent thoughts of death or recurrent suicidal thoughts.

At least one symptom needs to be depressed mood or reduced interest and pleasure. The prevalence is 3% to 7%.

There are several courses of depression:

1. Major depression
   This refers to a lot of symptoms for a brief period of time.
2. Minor depression
   This refers to moderate symptoms for a brief period of time (i.e. not a diagnosis).
3. Recurrent depression
   This refers to a recurrent form of major depression.
4. Chronic depression
   This refers to a lot of symptoms for a longer period of time.
5. Dysthymia
   This refers to moderate symptoms for a longer period of time (i.e. more than a year).
6. Bipolar disorder
   This refers to a lot of changes between highs and lows (e.g. depressed mood).

The prevalence of depression increases with age and peaks in adolescence and emerging adulthood, especially for females. The relapse rate of depression is 40% to 70%.

There rise in depression in adolescence may be explained by several things:

• It is a life phase with great biological changes.
• Peers become more important.
• There is more distance from parents and this can lead to conflicts.
• There is a greater independence and a greater need for executive functions.

Hormones sensitize brains for harmful effects of stress and this is especially the case for girls, partially explaining the higher prevalence of depression in girls. Peer relationships require work and depression can lead to isolation, exacerbating the disorder.

The difference in depression rates between males and females may be explained by several things:

• Society’s emphasis on gender roles, especially during adolescence.
• Girls’ greater body shame.
• Females experiencing more stress.
• Females having a stronger focus on interpersonal relationships.

About 40% to 70% of adolescents with depression have a comorbid disorder with anxiety (30%) and ADHD (15%-30%) being very common. This may be due to common factors such as a difficult temperament and a deficient emotion regulation. Depression is characterized by a downward spiral.

The information processing theory holds that when a person is depressed they have negative views about themselves, the world and the future. The diathesis-stress model states that the interaction between a predisposition for depression and stressors leads to depression.

The attribution theory states that a negative attributional style leads to and maintains depression. Negative experiences are attributed to internal and stable causes and it is generalized or global (e.g. “I am stupid”). Positive experiences are attributed to an external and unstable cause with specific attributions to the situation (e.g. “this exam was easy”).

Beck’s depression model states that early experiences lead to core beliefs and assumptions. Afterwards, there is a critical incident (e.g. failing a course) and this activates the assumptions. This, in turn, leads to negative automatic thoughts which subsequently leads to symptoms of depression. The symptoms of depression maintain the negative automatic thoughts.

The competence model of depression holds that the environmental reaction to depression is important in the maintenance of the disorder. To illustrate, depressive symptoms can lead to attention or concern by others and this may reinforce the symptoms. Alternatively, depressives symptoms can lead to unattractive behaviour (e.g. withdrawn) and this can lead to rejection or isolation, which can maintain the disorder.

Social support, adequate coping styles and thinking styles can help. There are several risk factors for depression:

• Emotional unavailability of parents.
• High family conflict.
• Economic difficulties.
• Parental divorce.
• Less contact with friends.
• Experiences of rejection.
• Poor peer relationships.

It is essential to check whether a person with depression (or depressive thoughts) to assess their suicidal thoughts and self-harming behaviour.

There are several guidelines for talking about self-harm:

• Always talk about it without judgement.
• Assess the risk of self-harm (1), nerve damage (2) or infections (3).
• Assess the function of self-harm and find an alternative behaviour for this.
• Know that secrets make it worse.

There are several guidelines for talking about suicide:

• Always talk about it without judgement.
• Assess the risk of self-harm or suicide.
• Know that secrets make it worse.

Self-harm is more prevalent in adolescence than in adulthood with about 3% of the adolescents performing self-harm. It increases the risk of suicidal ideation although it does not always lead to suicide. Talking about suicide or self-harm does not increase the risk of it. Suicide is often preceded by a period of months in which family problems have worsened. It takes place after a series of difficulties extending over months or years. There are several warning signs of adolescent suicide:

• Direct suicide threats.
• A previous suicide attempt.
• Preoccupation with death in music, art and personal writing.
• Loss of a family member, partner or pet through death, abandonment or breakup.
• Family disruptions (e.g. serious illness; relocation; divorce; unemployment).
• Disturbances in sleeping and eating habits and in personal hygiene.
• Declining grades and lack of interest in school or leisure activities.
• Drastic changes in behaviour patterns.
• Pervasive sense of gloom, helplessness and hopelessness.
• Withdrawal from family members and friends and feelings of alienation from significant others.
• Giving away prized possessions and getting their affairs in order.
• Series of accidents or impulsive, risk-taking behaviour (e.g. alcohol abuse) and disregard for personal safety.

A personality disorder refers to an enduring pattern of inner experience and behaviour that deviates markedly from the expectations of the individual’s culture. It is pervasive (1) inflexible (2) and stable over time (3). It is an often complex pathology that appears to be refractory to outpatient treatment.

There are three clusters of personality disorders:

• Cluster A (i.e. odd or eccentric disorders)
  This includes paranoid (1), schizoid (2) and schizotypal (3) personality disorders.
• Cluster B (i.e. dramatic, emotional, or erratic disorders)
  This includes antisocial (1), borderline (2), histrionic (3) and narcissistic (4) personality disorders.
• Cluster C (i.e. anxious or fearful disorders)
  This includes avoidant (1), dependent (2) and obsessive/compulsive (3) personality disorders.

It is unclear whether a personality disorder can be diagnosed in adolescence as personality is still in development and the symptoms are unstable. However, the disorder often has its onset in adolescence or emerging adulthood and is common in adolescents.

There is a greater risk for having a broad range of problems (e.g. depression; substance abuse) for people with personality disorders. Adolescents with personality disorders have a greater risk of taking problems into adulthood. This means that early diagnosis and treatment is beneficial. The DSM-5 holds that personality disorders can be diagnosed when maladaptive personality traits are present for more than a year.

Anorexia nervosa refers to intentional self-starvation and the prevalence is 1 in 200. Bulimia is common in anorexia nervosa. To be diagnosed, a person needs to lose at least 15% of their body weight due to restricted food intake. Cognitive distortions are common. Bulimia refers to binge eating combined with purging (i.e. intentional vomiting) and the prevalence is 3%. There are some characteristics of eating disorders:

• It is more common in cultures that emphasize slimness as part of the female physical ideal.
• It is more common among middle to upper socioeconomic class females.
• It is more common in females in their teens and early 20s.
• It is more common in females who are exposed to the thin ideal often.