What Causes Mental Illness in Adolescence

by Polaris Teen Center | Nov 15, 2018 | Mental Health, Resources, Treatment

adolescent with mental illness

Although it is often assumed that young people are more carefree than adults, their lives are full of emotional ups and downs. This is hugely evident in the statistics regarding adolescent and teen mental health, with as many as one out of every five adolescents and teenagers meeting the criteria for a diagnosable mental illness.  Additionally, 50% of all lifetime cases of mental illness will develop by age 14, and 75% by age 24. The most common mental health disorders in adolescents and teens fall into the categories of: anxiety disorders, stress-related disorders, mood disorders, obsessive-compulsive disorders, eating disorders, and disruptive-behavioral disorders (i.e. – attention-deficit/hyperactivity disorder or oppositional defiant disorder).

And while almost all adolescents and teens will experience periods of moodiness, crankiness, and/or angst, there are certain indicators that could demonstrate the presence of a more serious issue including:


  • Becoming socially withdrawn
  • Pervasive moodiness, lasting more than a few days
  • Dramatic changes in eating habits (including changes in weight)
  • Ongoing anger, irritability, or hopelessness


If your adolescent or teenager is demonstrating any signs of a more serious issue, they may need residential mental health treatment.  This is especially true if there are certain factors that may make him or her more susceptible to a mental illness.

Biological Factors

Biological factors refer to anything physical that can cause an adverse effect on a person’s mental health, and mental illness has a long history of biologically based evidence.  This is not surprising, as realistically, all human behavior is triggered by brain activity. Thus, it is understandable that sadness, fear, etc. originate in the brain. In the same regard, many mental health disorders have been linked to an abnormal balance of chemicals (neurotransmitters) in the brain.  Neurotransmitters are what help nerve cells communicate with one another, and, if out of balance, may cause messages to not be delivered properly, thus leading to symptoms of mental illness. Other biological factors considered as possible contributing factors to mental illness include:


Genetic factors have been shown to play a significant role in the development of mental disorders in adolescents (and in general). There are three major ways in which genetics contribute to mental illness:

  1. Genes govern organic changes or abnormalities in the brain, which can predispose an adolescent to diagnoses such as schizophrenia and Alzheimer’s disease.  
  2. Genes can be responsible for abnormalities in an adolescent’s development (before or after birth).  This means mental disorders develop as a result of chromosomal mutations or deletions.
  3. Genes may influence one’s susceptibility (or vulnerability) to depression, anxiety, personality, and/or substance abuse disorders.   Children and adolescents who have a first-degree relative with mental illness (i.e. – depression, anxiety, PTSD) are at a higher risk for the development of their own mental health disorder(s).
Brain injury

Any injury to the brain can cause mental illness in a person, as the brain is the control center for the nervous system and entire body.  Many studies show higher rates of substance abuse, mood, and psychotic disorders following a traumatic brain injury. Head trauma can cause injury to the brain, as well as brain tumors.  

Infection or Disease

Although this tends to be the area most mysterious in terms of causes of mental illness, some studies have linked mental illness to certain viruses or infectious diseases.  Additional research regarding the connection between infectious disease and mental health disorders is needed to continue to shed light on the phenomena of viruses, diseases, and infections manifesting as mental illness.

Prenatal Damage

Any harm or injury that occurs to a fetus while in the mother’s womb is considered prenatal damage.  Prenatal damage is, in some cases, a strong contributing factor to the likelihood an adolescent or teenager will develop a mental illness.  Prenatal damage can occur if the pregnant mother uses drugs and/or alcohol, or is exposed to certain infections or illnesses during pregnancy.  Prenatal damage can also occur if the pregnant mother is under significant stress or experiences trauma during pregnancy. Additionally, there have been instances of prenatal damage due to loss of oxygen to the brain (often connected to the development of autism) or a difficult (traumatic) birth process. 

Substance abuse 

Any substance abuse, especially long-term use and abuse, can cause the development of mental illness in adolescents. Substance abuse can also contribute to increased symptomology in pre-existing mental illness. Many studies indicate a strong correlation between alcohol abuse and depression, while others show a connection between the abuse of amphetamines and anxiety disorders.  Even caffeine abuse over a long period of time has been shown to contribute to the development of anxiety.

Environmental Factors

Unlike psychological or biological causes, environmental causes tend to be difficulties or stressors that adolescents deal with on a daily basis.  Environmental causes are psychologically based, but tend to be pervasive in a person’s life (sustain for longer periods of time). Environmental causes of mental illness in adolescents are typically, at their core, a result of stress.

Common sources of stress in adolescence are social stress, isolation, or substance abuse.  Other common sources of stress include:

  • Trauma – emotional, sexual, or physical abuse
  • Bullying
  • Demands at school or work
  • Unstable or dysfunctional home environment – for example, domestic violence in the home.
  • Early loss – such as the loss of a parent or sibling
  • Unsafe living conditions
  • Obesity
  • Chronic illness
  • Natural disaster
  • Car accident
  • Acts of violence – such as school shootings
  • Witness another person experience a traumatic event
  • Cultural or social expectations – societies that value beauty connected to thinness can be a factor in the development of eating disorders
  • Feelings of inadequacy – low self-esteem, anger, anxiety, and/or loneliness

Indicators of stress overload in adolescents may include frequent illness, withdrawal from friends, family, and/or activities, changes in eating and sleeping habits, anger/irritability, and expressing hopelessness.

It is important, as a parent or caregiver to be aware of what is going on with your child, not only behaviorally but also emotionally.  Everyone is different and is affected by stress, life experiences, and emotions in different ways, but with the prevalence of mental illness in adolescents and teens, there is a chance your child may be affected.

For more information on Polaris Teen Center, or to find out about our mental health programs, contact our admissions team at (844) 836-0222 today.

Polaris Teen Center | Website | + posts

Polaris Teen Center is a residential treatment facility for teens and adolescents suffering from severe mental health disorders. Our highly accredited facility is fully licensed and certified in Trauma Informed Care and is a part of the Behavioral Health Association of Providers (formerly AATA).