Common Mental Illnesses Among Adolescents: Definitions and Effects

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One in five adolescents has a history of serious mental illness, according to the Office of Adolescent Health1. The most common mental health conditions among adolescents are anxiety, depression, ADHD, eating disorders and substance use disorders.

Anxiety Disorders

Around 32 percent of 13- to 18-year-olds suffer from an anxiety disorder. Anxiety disorders are characterized by feelings of extreme uneasiness, fear, and worry. It’s normal for adolescents to have some anxiety around school, social relationships and other areas of life. But when anxiety interferes with daily life and quality of living, it can take a serious toll on anyone. Common anxiety disorders include:

  • Generalized anxiety disorder, characterized by excessive, long-lasting anxiety
  • Panic disorder, marked by frequent panic attacks, or bouts of sheer terror
  • Post-traumatic stress disorder, which often results from trauma
  • Social anxiety disorder, which can make social situations excruciating
  • Obsessive-compulsive disorder, which is characterized by repetitive behaviors and intrusive thoughts
  • Phobias, or irrational fears


One in eight adolescents and young adults suffer from depression, which is characterized by a depressed mood and feelings of helplessness and hopelessness. Depressive disorders include:

  • Persistent depressive disorder, which is a depressed mood that lasts for at least two years
  • Seasonal affective disorder (SAD), characterized by depression during the winter months when there’s less sunlight
  • Bipolar disorder, formerly known as manic depression, which is characterized by recurring depression alternating with periods of mania, or intense activity
  • Disruptive mood dysregulation disorder, a childhood condition characterized by extreme irritability, anger and frequent outbursts

Attention Deficit-Hyperactivity Disorder (ADHD)

ADHD is characterized by the inability to focus and often includes hyperactivity and impulsive behaviors that make it difficult for a child to function. It can also interfere with normal development. Around nine percent of 13- to 18-year-olds have ADHD.

Eating Disorders

Eating disorders are characterized by abnormal or extreme eating behaviors, including eating too little or too much. Nearly three percent of 13- to 18-year-olds have an eating disorder. While they’re more common among girls and women, eating disorders also affect boys and men. Eating disorders develop for a number of reasons, including low self-esteem and as a response to trauma. The most common eating disorders are:

  • Anorexia nervosa, which is characterized by dramatic weight loss and extreme under-eating or excessive exercise
  • Bulimia nervosa, characterized by bingeing on food and then purging it through vomiting or the use of laxatives
  • Binge eating disorder, which is characterized by eating a large amount of food in a short period of time, without purging behaviors

Mental Illness and Substance Abuse

Mental illness is frequently an underlying cause of substance abuse, and substance abuse can cause the onset of a mental illness, according to the National Institute on Drug Abuse2. Adolescents face a greater risk than adults for developing drug or alcohol problems, especially if they have a mental illness.

When a mental illness and a substance use disorder occur together, it’s known as a dual diagnosis or co-occurring disorders. Co-occurring disorders require specialized treatment that addresses the substance abuse in the context of the mental illness and vice-versa. Addressing just the mental illness or just the substance abuse is largely ineffective for treating either disorder.

Some important signs that your child may be abusing drugs or alcohol include:

  • Paraphernalia, such as pipes or baggies
  • Changes in mood, appetite or sleeping patterns
  • Withdrawing from friends and family
  • Losing interest in activities they used to enjoy
  • Periods of elevated activity or subdued activity
  • Changes in their social group
  • Bloodshot eyes or pinpoint pupils
  • Secretive behaviors


  1. Mental Health in Adolescents
  2. Comorbidity: Addiction and Other Mental Illnesses

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