Mental illness definition

A mental illness, according to APA, is a health condition involving changes in emotion, thinking, behavior, or a combination of all these. It is associated with distress or problem functioning in society, work, or family activities. And just like the phrase “physical illness” encompasses many different types of physical problems, mental illness might describe a vast array of mental illness issues. And remember, having a mental illness does not mean someone is crazy as many of us think. It means that there are changes in chemical production, either too much or too little, in the brain. But what causes these chemical imbalances? What causes mental illness?

What are the causes of mental illness?

Although the causes of most mental illnesses are not known, research shows that a combination of conditions such as biological, psychological, and environmental factors can be the cause. How does each one of these factors affect your mental health? Well, let’s take a look at them.

What causes mental illness?
Mental illness and its causes

Biological factors

  • Genetics: Sometimes, mental illnesses run in the family. Scientists believe many mental illnesses are linked to abnormalities in many genes rather than just one or few genes that how these genes interact with the environment is unique for every person.  That is why a person inherits a susceptibility to mental illness and doesn’t necessarily develop the illness. Mental illness itself occurs when other factors such as stress, trauma can trigger an illness in a person who has an inherited susceptibility to it.
  • Infection: certain infection has been linked to brain damage. For instance,  a condition is known as pediatric autoimmune neuropsychiatric disorder (PANDA) associated with the Streptococcus bacteria has been linked to the development of the obsessive-compulsive disorder and other mental illnesses in children.
  • Brain defects or injury: Defects in or injury to certain areas of the brain have also been linked to some mental illnesses.
  • Prenatal damage: Loss of oxygen to the brain at the time of birth can be a factor in the development of certain conditions, such as autism spectrum disorder.
  • Substance abuse: long-term substance abuse has been linked to anxiety, depression, and paranoia.
  • What causes mental illness?
    Mental illness and its causes

    Other factors: Poor nutrition and exposure to toxins, such as lead, may play a role in the development of mental illnesses.

Psychological factors

  • Childhood trauma includes emotional, physical, and sexual abuse,
  • Poor ability to relate to others
  • Neglect
  • An important early loss such as the loss of a parent.
Environmental factors
  • Chronic stress
  • Poor nutrition
  • Stressful life events
  • Social or cultural expectations
  • A dysfunctional family life
  • Change of jobs or schools
  • War
  • Poverty


What causes mental illness?
Mental illness and its causes.
  • Divorce
What really matters after the diagnosis?

The first step to getting better is seeking professional help. Mental illness is treatable, the most important decision one could make is to acknowledge and accept the diagnosis. Your next step is to educate yourself about your condition and your best options for treatments. You also need to understand that it might take, you and your care team, a little time to figure out the best course of treatment that suits your needs. Thirdly, surround yourself with those who love, support, and care for your well being.

If you or your loved ones are in distress, please contact the National Institute of Mental Health

When in crisis, there is free help available here

If you are thinking of suicide or know someone who might be considering suicide, help is a call away at :

Call 800-273-8255 
Text 273TALK to 839863 
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Call 800-923-4357 
Text RecoveryNow to 839863 
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For individuals and family members seeking crisis intervention, treatment referral, and chemical-dependency information.
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Call 888-457-4838 (24/7/365)
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Call 503-200-1633
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Call 877-968-8491
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Not ready to call? Find local and national mental health and substance abuse resources for those struggling, and those with loved ones who are struggling.
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Raina is a psychology student who understands the importance of caring for mental health. She blogs about depression, anxiety, fibromyalgia, men and mental health and parenting kids with ADHD.


    • Mental illness are such an everyday thing nowadays. I know back in the days people were ashamed to admit they have it. Today luckily there are more support and openess about it. Not nice however when you inherit a mental illness haha

      • Leana,

        Even nowadays, people are not ready to talk about their struggle with mental illness, but I hear you, it’s better than what it was back in the days as you had said.

  1. I loved reading this vitally important blog article about what causes mental illness. I know alot of it is social environment but many mental illnesses are simply genetic. My family has a history of suffering from chronic depression and post-partum depression runs on my Mother’s side. I love your blog graphic as well! Take care.

    • Beth,

      Yes, a lot of mental illness stems from the social environment. It can be difficult for family members to disclose their struggles with mental illness. Back in the days when mental illness was not a disease, many suffered in silence. My mother’s side has a history of depression and bipolar but was never diagnosed. My mother has now passed but I still remember how severe her depression was and how it affected our family. Genetic did play a major role in her case but her environment surely contributed to a great level of her depression. Thanks for sharing your story.

  2. Kate Murray Reply

    I love that you’ve shared resources for people who need help! It’s so hard to be able to ask for help for some, so having a list of places they can get help is critical!

    • Kate,
      I agree with you, some people find it difficult to ask for help. So having these resources available for people can hopefully make a bit easier to seek for professional help.

  3. Thank you for such an informative post. My son has mental illness and it really is so important to get people help and if anyone is suffering for them to find a safe place to get that help. Really appreciate you placing contact details for readers.

    • Julie,

      I am glad you found this post informative. Taking care of someone with a mental illness can be challenging. I hope you have all the support you need to care for your son.

      • I really think mental illness is the toughest one of all. Bc I feel like you can’t really control it. And genetics has a big part in that, at least from what I saw. You need to be very strong but I also now that because of that same illness you are sometimes not able to.

  4. It is so important that people understand what causes mental illnesses and that the assumption that people are crazy needs to be changed asap! Thank you for the breakdown on how mental illnesses might occur and including resources on how to get help.

    • Tina,
      I agree with you, it’s important to understand what causes mental illnesses and how people can help their loved ones. Mental illness is not about someone being crazy or weak, it’s a serious illness that can be treated with proper treatment.

  5. I know members in my family suffer from mental illness and don’t say anything because they don’t to be labeled as crazy or seen differently. We don’t talk about mental health issues openly enough. I love that you explained how mental illnesses occur. I think that is important to understand the different factors that cause. Great article!

    • Vicki,

      It can be extremely difficult for people to seek for professional help when no one in their family has openly shared their experience. Thanks for the reading.

  6. It is clear you have worked hard and done a lot of research for this post. All the sites you shared at the end are amazing. It is so difficult to ask for help and going to one of those sites is definitely a good first step. It is what I did ? I am a mental health blogger too by the way. Your blog is awesome!! :3

    • Ruth,

      Thank you for your kind words. I hope people would be able to utilize these resources to seek professional help and get better. What is the URL for your site? I love meeting bloggers in my niche, would love to visit your blog.

  7. Mental illness – just the phrase triggers off judgement with most people. It’s taboo to talk about any mental issues because of the assumptions that go with it. There isn’t enough awareness about the topic for people to truly understand and be compassionate, Raina. It is scary to see the countless ways mental illness can be triggered. Sometimes, it is not even clear what caused it. Thank you for the listed resources. I think people going through the spectrum of mental health issues often have no idea whom to turn to or contact for help. Comprehensive post! Thank you for creating awareness.

    • Vidya,

      Thank you for your support and for doing your part in bringing awareness to the subject. I hope in sharing my experience with mental illness, others will be encouraged in seeking help and opening up about their own experience which will then reduce the stigma associated with mental illness.

  8. Thank you for this fantastic resource Raina. I’m no stranger to mental illness as a recovering alcoholic and drug addict with bipolar disorder.

    Mental illness is very much misunderstood and stigmatized yet so many people suffer from mental health problems. Like you say there are so many factors that come into it and it is not easy to pinpoint the exact cause of mental illness.

    From my side it certainly runs in the family with depression, anxiety and addiction. I’ve also been through some traumatic experiences in my teenage years which most definitely got me spiraling out of control.

    Thankfully there is a lot that can be done to manage one’s mental health and I am so grateful to be 11 years sober now and being able to function in society!

    • Lynne,

      I am so proud of you and the progress you have made, 11 years is a long time of sobriety. You are an inspiration to a lot of people out there. You are not only able to function in society but you are also an influencer in the blogging world, kudos to you.

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