Mental illnesses are complex and involve multiple biological, genetic, familial, social, medical, and socioeconomic factors.

This article will explore 9 of the most common causes of mental illness.

As you read, remember that no single factor causes mental illness entirely, it’s always a combination of factors, and they express differently for different people. What is a significant factor for one person may be insignificant for another.

1. Early negative life experiences

Adverse Childhood Experiences (ACEs) are potentially traumatic experiences children go through. During these vulnerable years, traumatic experiences like witnessing violence or growing up with mentally ill parents increase the risk of developing various physical and mental illnesses. 

According to the CDC, preventing ACEs could reduce cases of depression by up to 21 million. It can also reduce cases of other illnesses such as heart disease, obesity, asthma, kidney disease, and strokes.

2. Chronic medical conditions

Being diagnosed and living with chronic illnesses increases the risk of mental illness. The sadness and uncertainty of the diagnosis, followed by the potential physical limits imposed by the disease, may deteriorate mental health.

The following chronic illnesses are associated with a higher risk of suffering mental illness:

  • Alzheimer’s
  • Autoimmune diseases like systemic lupus erythematosus and rheumatoid arthritis
  • Cancer
  • Coronary heart disease
  • Diabetes
  • Epilepsy
  • Hypothyroidism
  • Multiple sclerosis
  • Parkinson’s disease
  • Stroke

If you feel sad for more than a few weeks after diagnosis or frequently feel sad when managing a chronic illness, you may suffer from a depressive disorder. You should seek mental health treatment in addition to the treatments and medications associated with the chronic illness.

3. Biological, genetic, and family-related factors

Mental illness combines biological, environmental, psychological, and genetic factors.

Researchers from the National Institutes of Mental Health have determined that specific genes and gene variations are associated with mental disorders. Specific gene variations cause genetic diseases like cystic fibrosis, but it’s much harder to pinpoint specific genes for mental illnesses.

Genetic testing and genome scans cannot accurately predict a propensity for certain mental illnesses as they may for genetic diseases. More research is needed to understand the genetic factors of mental illness.

Of course, our genetic propensities will still be influenced by other factors, such as chronic illnesses, a family history of mental illness, traumatic experiences, and others. Mental illnesses like schizophrenia also run in families, but the exact reasons are not fully understood.

4. Chemical imbalances in the brain

You may have heard that chemical imbalances in our brains are the main reasons driving mental illness. Some evidence suggests that chemical imbalances play a role in mental illness, especially depression, bipolar disorder, and anxiety.

Postpartum depression, for example, is associated with hormonal changes during and after giving birth. In the case of bipolar disorder, some researchers theorize that dopamine imbalances contribute to its symptoms.

However, mental illnesses are complex, and chemical imbalances are unlikely to be the only cause.

5. Drug addiction

According to the National Institute on Drug Abuse, there’s a well-known association between mental illness and substance use disorders (SUD). This manifests as people with mental illness being more likely to suffer SUDs and vice versa. Some examples include:

  • Over 60% of adolescents in community-based SUD treatment programs also meet the criteria for other mental illnesses.
  • There are high rates of comorbid anxiety disorders and SUDs, meaning that people with anxiety disorders have a higher risk of SUDs.
  • The same goes for depression, ADHD, and antisocial personality disorder.
  • Patients with schizophrenia have a higher risk of abusing alcohol, tobacco, and other drugs.

This doesn’t mean that SUDs and mental illness directly cause each other, but they are highly likely to co-occur.

6. Feeling lonely and isolated

Loneliness, isolation, and mental illness are associated and may reinforce each other. For example, people with social anxiety struggle to make meaningful social connections because of their symptoms, which may make them feel isolated and lonely. In other cases, feeling socially isolated and lonely can exacerbate mental illnesses. 

A vicious cycle may ensue: mental illness symptoms may affect self-esteem and lead to loneliness, which worsens symptoms and increases feelings of isolation and loneliness. This cycle repeats and makes it harder to recover.

7. Experiencing discrimination and social stigma

Experiencing social separation stress caused by racism and discrimination, quarantines related to infectious disease containment, and the socio-demographic changes associated with old age play a role in altering the function of some of our neurotransmitters (chemical messengers in our brain and nervous system).

Especially in children, stress from social separation and discrimination may have lasting effects and increase our chance of suffering mental illnesses and SUDs.

8. Socioeconomic factors

Various socioeconomic factors play a role in our mental health, including the following:

  • Social disadvantage.
  • Poverty.
  • Debt.
  • Unemployment or losing your job.

A low SES (socioeconomic status) is associated with more frequent mental health problems. People with the lowest SES might be two to three times more likely to have a mental disorder than those with the highest SES. 

People from disadvantaged environments often don’t have the appropriate resources to respond effectively to illness and other life challenges. The uncertainty, conflicts, and threats from these lead to chronic stress, accumulating throughout life and degrading mental health over time.

9.  Head trauma

Concussions and other traumatic brain injuries (TBI) may cause mental illness symptoms or worsen existing ones, such as anxiety, depression, mood swings, anger, post-traumatic stress disorder (PTSD), and more. 

Patients receiving post-TBI treatment often experience symptoms like:

  • Emotional imbalances.
  • Newfound inability to control their temper.
  • Hopelessness.
  • Overwhelming feelings when facing minor everyday challenges like dropping a dish and breaking it.

Symptoms like these are widespread and often cause shame in those who suffer from them. Treatment for these may include medication and cognitive behavioral therapy specific to TBIs.

Seek help for mental illness

Millions of people in the US and the world live with mental illness, diagnosed or otherwise. They are prevalent, but there has long been an unfortunate stigma to being seen as mentally ill. People living with mental illness need treatment, not isolation.

To start, learn to recognize common general symptoms of mental illness. Some of them include the following:

  • Feeling sad often.
  • Inability to focus.
  • Guilt.
  • Extreme mood changes.
  • Low energy and sleepiness.
  • Delusions and other detachment from reality.
  • Drug use.
  • Changes in eating habits.
  • Changes in sex drive.
  • Anger and hostility.
  • Suicidal thinking.

If you or a loved one experiences these symptoms, seek treatment by visiting qualified therapists near you or through qualified online platforms. Mental health is just as important as physical health; you need to treat mental illnesses like any other disease.