What Causes Mental Illness?

Mental illnesses are brain-based conditions that affect your feeling, thinking, behavior and mood. They are very common, affecting nearly one in five adults in the U.S. and representing about 19% of the total population.

Mental illness is caused by issues associated with the brain, which changes based on life experiences such as trauma, nutrition and stress. When the brain changes the way it works, it might result in a mental illness.

Having negative thoughts is normal; only when they affect your ability to do the things you want can this be diagnosed as mental illness. You can also be diagnosed with mental illness if the negative thoughts are persistent or stay longer than they should.

How Common Is Mental Illness?

Anyone can be affected by mental illness regardless of gender, age, social status or race. Many people start experiencing mental illness in their mid-20s. In the U.S., almost half of the population has experienced mental health issues at one point, with half of these people experiencing it by age 14. According to studies, people of color, women and members of the LGBTQ community are more likely to experience mental illnesses because of the unique stressors in their lives.

Unfortunately, most people suffering from mental illnesses do not receive treatment. Additionally, most people are not diagnosed with mental illnesses until they have been suffering for a long time. Mental illness is treatable using medication and other lifestyle changes that can improve mental health.

Types of Mental Health Issues and Illnesses

Suffering from a mental illness alters the brain, making it difficult to feel, think or act normally. People are affected differently, sometimes, experiencing extreme and unexpected mood swings like feeling more sad than normal. Others are not able to think or communicate clearly, or they have strange thoughts to explain their bizarre feelings.


Depression is a mental illness characterized by loss of interest and enjoyment, low moods and reduced energy. It manifests itself in various ways and has varying levels of severity. Some of the feelings caused by depression include irritability, guilt, sadness, frustration, misery, unhappiness and lack of confidence. A person may experience sleep problems, weight loss or gain, tiredness, headaches, muscle pain or loss of appetite. Some of the causes of depression include family history, serious medical conditions, and drug and alcohol use.

Bipolar Disorder

Bipolar disorder causes periods of mania and depression with periods of normal moods in between. Some of the symptoms include racing thoughts, lack of sleep, lack of focus, irritability, frustration and sudden bursts of energy. Other symptoms include delusions or hallucinations and loss of touch with reality.

Anxiety Disorder and Panic Disorder

Anxiety disorders can include panic disorders, phobias, social anxiety and generalized anxiety disorder. People with anxiety show physical signs of panic such as sweating and rapid heartbeat and fear response to certain situations or people. Diagnosis for anxiety happens when someone cannot control their responses or cannot function normally.

Post-Traumatic Stress Disorder

PTSD occurs after a terrifying or traumatic event such as physical or sexual assault, death of a loved one or a natural disaster. It causes frightening thoughts and triggers painful memories of the event.

Personality Disorders

A personality disorder causes a person to have unpredictable and extreme personality traits that can lead to social and personal-life problems. A person may show abnormal social behavior, which may interfere with normal functioning. Some forms of personality disorder include schizoid personality disorder, histrionic personality disorder and paranoid personality disorder.

Psychotic Disorder or Schizophrenia

People suffering from psychotic disorders experience distorted thinking and awareness. They also experience hallucinations and delusions. An example of a psychotic disorder is schizophrenia.

Eating Disorders

Eating disorders include bulimia nervosa, anorexia and other binge-eating disorders. These disorders lead to extreme attitudes, emotions and behaviors involving food and weight. They can have severe physical and psychological effects.

Other Disorders

Other common mental illnesses include:

• Attention deficit hyperactivity disorder (ADHD)
• Obsessive-compulsive disorder (OCD)
• Stress response syndrome
• Dissociative disorders
• Factitious disorders
• Sexual and gender disorders
• Somatic symptom disorders
• Tic disorders
• Impulse control and addiction disorders
• Dissociation and dissociative disorders
• Psychosis

Causes of Mental Illness

There is no single cause of mental illnesses, but various risk factors increase your chances of suffering mental illnesses. You can develop mental illness gradually, or it can happen spontaneously when triggered by a traumatic event. Most mental illnesses are caused by a combination of psychological, biological and environmental factors.

Biological factors

Here are the primary biological factors that may lead to mental illnesses.


Mental illness can run in the family, meaning that there is a high possibility that a person who has a family member with a mental illness may also develop one. This is passed down through genes; it is believed that mental illnesses are linked to abnormalities in multiple genes instead of a single one. It also depends on how the genes interact with the environment, which varies from one person to another. This explains why a person can inherit a susceptibility to a mental illness but fail to suffer from the illness and vice-versa. Mental illnesses occur when multiple genes interact with other factors such as abuse, stress or a traumatic event.

Brain Injury or Defects

A person can develop mental illnesses due to an injury or defect in certain areas of the brain.


Various infections can lead to brain damage and cause mental illnesses or worsen their symptoms. Examples of such infections include pediatric autoimmune neuropsychiatric disorder, which can lead to OCD.

Substance Use Disorder

Long-term substance use disorder can cause mental illnesses such as depression, anxiety and paranoia.

Other Factors

Other biological factors that can cause mental illnesses include exposure to toxins like lead. Poor nutrition and disruption of early fetal brain development or damage at birth may lead to mental health issues.

Environmental Factors

Various environmental factors can trigger mental illness in a person, including:

• Divorce
• Death of a loved one
• Change of schools or job
• Low self-esteem
• Cultural or social expectations
• A dysfunctional family life

Psychological Factors

Life experiences can lead to mental illness. Some common factors include:

• Neglect
• Childhood trauma
• Sexual abuse
• Poor ability to relate to others
• Loss of a parent
• Physical abuse
• Negative thoughts
• Unhealthy habits

Is Mental Illness Genetic?

As mentioned above, genetics is a risk factor that can lead to mental illness. Genes are passed down from parents to their children and provide a blueprint for developing the brain and body. However, it is not that simple, and how genetics are associated with mental illness is a complicated issue. There is no specific gene that can lead to a mental illness; instead, it is a result of many genes combined with other factors.

It is crucial that you know your family history of members who have been treated for mental illness. This can help you know the medications that worked and those that did not. However, treatments for mental illnesses vary from one individual to another, and what works for you may not work for another person even if you are suffering from the same illness.

Knowing your family history will also help you make better lifestyle choices. For example, you may want to stay away from drug and substance use if addiction runs in your family.

You may want help from a counselor when going through a traumatic experience to avoid falling into depression, especially if it’s common in your family history.

Diagnosing Mental Illnesses

Mental health screening examines your emotional health to find out if you are suffering from mental disorders. You may need to take a mental health screening to determine whether you need to visit a mental health provider. A mental health provider helps to diagnose and treat mental health illnesses. You may also need screening to determine the best course of treatment.

A mental health screening is crucial if you are suffering from symptoms of mental illnesses. Common symptoms include:

• Sadness
• Frustration
• Dramatic mood swings
• Worries and fear
• Fatigue
• Trouble concentrating
• Personality changes
• Lack of sleep or appetite

Suicidal thoughts are one of the most severe signs of mental illness. If you or your loved one is thinking about suicide, seek help immediately. You can call 911 or your mental health provider for help. You can also dial the National Mental Health Hotline at 866-903-3787.

During a mental health screening, you are given a physical exam where you are asked about your mood, feelings and behavior patterns. A blood test is sometimes needed to determine if there is a physical disorder causing mental illness symptoms. The blood is typically drawn from a vein in your arm and tested.

If the results indicate that you have a mental illness, you need to get treatment right away. The treatment plan will depend on the type of illness you are suffering, but the goal is to help prevent disability or long-term suffering.

Various mental health providers can conduct a mental screening, including a psychiatrist and a psychologist. A psychiatrist diagnoses, treat and prescribes medicine for mental illnesses. On the other hand, a psychologist offers counseling sessions and can diagnose mental illnesses. Other specialists include therapists and counselors who diagnose mental health problems but cannot prescribe medicine.

Treatment for Mental Health Problems

Treatment for mental illnesses varies depending on the illness, the severity and what works best for you. Severe mental illnesses such as schizophrenia require special treatment and team effort from a medical care provider and family members. Other professionals involved in treatment may include social workers, physician assistants or psychotherapists.


There are no specific medications to cure mental illnesses. However, some treatments can help to dramatically reduce the symptoms. They also enhance other forms of treatment such as psychotherapy and increase their effectiveness. Here are some of the common medications used in treating mental illnesses.


Antidepressants are used to treat anxiety, depression and other mental illnesses. They help improve symptoms such as hopelessness, sadness, lack of sleep, lack of concentration and lack of energy. Antidepressants do not typically lead to dependency since they are not addictive.

Mood Stabilizers

Mood-stabilizing medication is mostly used to treat bipolar disorder, which causes periods of depression and mania. They can be used together with antidepressants to treat depression.

Anti-Anxiety Medication

Anti-anxiety medications are commonly used to treat anxiety disorders such as panic disorder or generalized anxiety disorder. They also help people with insomnia and reduce agitation. This type of medication can be addictive and lead to dependency.

Antipsychotic Medication

Antipsychotic medications are used to treat psychotic disorders such as bipolar disorders or schizophrenia. They can be used together with antidepressants to treat depression.


Psychotherapy involves talking about your mental illness, including its symptoms and how it affects your moods and behavior. This helps to give you knowledge and insight to learn stress management skills. There are various approaches to psychotherapy, and it can take time to see results, typically a month or more depending on the type of mental illness. The therapist you choose should have excellent listening skills and understand your life journey.

Brain-Stimulation Treatment

These treatments are usually used for depression and are mostly used where other medications have not worked. They include repetitive transcranial magnetic stimulation, electroconvulsive therapy, vagus nerve stimulation and deep brain stimulation. Brain-stimulation treatments have their benefits but also have risks.

Hospital and Residential Treatments

When a mental illness is severe, a person may be taken into a psychiatric hospital. This is necessary with reduced functionality so that a person can’t hurt themselves or others. Hospital treatments offer various options such as 24-hour inpatient care, partial treatment or residential treatment. Substance use treatment can also be administered by a residential facility.

Lifestyle and home remedies

There are various activities that you can do to ensure that the treatment plan works as effectively as possible. They include the following:

• Avoiding the use of drugs and alcohol
• Following the treatment plan
• Staying active
• Making healthy choices
• Adopting a positive attitude
• Determining priorities

Your mental illness may not go away completely, but it can be managed, so it is essential that you learn how to cope with it. You can start by learning about your mental illness, including the causes, risk factors and treatment options. Joining a support group will help you to connect with others going through similar challenges. Family and friends can help you through their love and support. You can also keep a journal to track your personal life and express your emotions.

Remember that mental illnesses are treatable. If you need help, you can reach out to the National Mental Health Hotline at 866-903-3787.