No One Cause
Based on current research, there is no one cause of schizophrenia. Schizophrenia is a combination of symptoms and behaviors that includes psychosis. In terms of behavior or biology, there is no one specific “thing” that is schizophrenia. It does not have one cause in part because it is not one thing.
Researchers do not know what causes mental illness in general. We almost never know what caused schizophrenia for any single person. Instead, research tells us about factors that increase risk for mental illness in general (rather than specifically for any individual). Risk factors can be things that make a person more vulnerable to developing schizophrenia. They can also be stressors in a person’s life that trigger symptoms or make a person more vulnerable to developing schizophrenia in the long run.
Trauma is one of the major factors that increases risk for schizophrenia, psychosis, and many other mental health problems. The American Psychologial Assocation defines trauma as “an emotional response to a terrible event like an accident, rape, or natural disaster,” although the word means different things to different people 1. Trauma and schizophrenia are clearly linked in general. For many (not all) individuals, there is a clear link between trauma and mental illness. So, the simple answer to “Can trauma cause schizophrenia” is: “Yes, but it’s complicated.” This answer has not changed through many decades of research 2-4. However, what this means for individuals, families, policy, and treatment is complicated and difficult.
As a psychologist with expertise in rehabilitation and recovery, I’ve spent my career working to improve the poor state of mental healthcare for and with individuals and families affected by serious mental illness including schizophrenia. I know that if we take a step back to look at the many different factors that combine to cause mental illness and recovery, we can find more helpful ways to think about how trauma can cause schizophrenia–including perspectives that will help individuals recover and families heal.
Searching for one “cause” of mental illness is usually unhelpful. But it is often helpful to try to understand the many “causes” that contribute to mental illness and recovery. The vulnerability-stress model is currently the best model to help understand something as complex as mental illness. It is also a more helpful way to think about if trauma can cause schizophrenia. Basically, the vulnerability-stress model says that many factors come together to cause mental illness and make things worse or better over time. Vulnerabilities include pre-existing risk factors in your body like genes or biology. Stressors are things that happen to or around you or things that you do in life that increase risk of developing mental illness or worsening symptoms.
Most people know that genetics and brain biology are a big part of what can make someone vulnerable to schizophrenia. This is shown in many individual stories where psychosis and other symptoms of schizophrenia “just happen.” In these cases, individuals have very high vulnerability to schizophrenia, and onset occurs in a way that seems clearly linked to brain development, regardless of stressors in the person’s life and environment. On the other hand, a disproportionate number of people with schizophrenia experienced trauma during childhood or around the time of symptom onset. Most people with schizophrenia experienced stressors in their life that contributed to the onset or worsening of symptoms in combination with their vulnerability. Beyond that, there are sadly people whose traumatic experiences make it difficult to imagine life without mental illness. In that case, it may be that little or no preexisting vulnerability is necessary to develop schizophrenia. In general, a combination of vulnerability and stress factors come together to increase risk for developing schizophrenia.
Trauma as an environmental risk factor and stressor
A wide range of stressors in life can increase risk for schizophrenia. Schizophrenia and related diagnoses are typically diagnosed when a person is in their teens or a young adult. During late adolescence and while symptoms are starting, trauma and many other stressors can greatly increase risk for schizophrenia 5. Trauma is considered an “environmental” risk factor that is strongly linked to serious mental illnesses like schizophrenia. Environmental risk factors are usually stressors from outside a person’s body rather than internal factors like biology or emotions. Environmental risk factors are very important to consider. A person’s environment is often easier to understand and change than genes or biology. Trauma is a significant stressor that may trigger onset of symptoms or contribute to worse symptoms compared to someone with schizophrenia and no history of trauma. In addition to trauma, cannabis use and poverty are also big environmental risk factors for schizophrenia 6.
The word “trauma” means different things to different people. Many clinicians use the word “trauma” only as defined in the diagnosis for posttraumatic stress disorder (PTSD), which means exposure to actual or threatened death, serious injury, or sexual violence 7. Or, clinicians may think of Adverse Childhood Events (ACEs). ACES are childhood problems (for example, physical or sexual abuse or neglect) that increase risk for problems in adulthood. ACEs, intergenerational trauma, and social determinants of health impact a child’s environment, opportunities, and physical and mental health into adulthood 8-10. In physical medicine, trauma refers to serious bodily injury. Prenatal and perinatal trauma (health problems in the womb or birth complications) or brain injury later in life are physical traumas that can contribute to risk for mental illness 11.
The word “trauma” is also used often colloquially - in everyday conversation with a broad definition. Many people now define “trauma” by its effect rather than by its severity. In this way, what is “traumatic” is very individual and depends on how a person experienced an event and how it lingers. During adolescence or adulthood, significant stressors and traumatic events are common in the time leading up to onset of serious mental illness, which suggests traumatic stress triggers the onset for many people. Whether these stressors are defined as “trauma” is less important than understanding and coming to terms with things that contribute to symptoms or quality of life.
Across the population, people with schizophrenia have experienced many more adverse childhood events and diagnosable traumas compared to the general population. PTSD is the only mental illness that requires trauma to be diagnosed. But having had childhood trauma and developing PTSD are both much more common for people with serious mental illness like schizophrenia. People with schizophrenia are more likely to have experienced trauma early in life, more likely to experience trauma after onset of symptoms, and more likely to have PTSD from childhood and adult traumas. However, serious mental illness and schizophrenia diagnoses do not require childhood trauma. Many people with schizophrenia had a well-adjusted, supportive childhood with no significant trauma. It is worth noting that even for PTSD there are other causes besides experiencing trauma. For example, there are research studies on twins who both experienced traumatic events during combat but only one was diagnosed with PTSD 12.
Thinking critically about how and why we explain the causes of mental illness
All of the explanations for what causes schizophrenia are valuable for different reasons. But all explanations for mental illness also have dangers, especially in terms of stigma and blame. It helps to consider the pros and cons of different ways of thinking about the causes of mental illness.
One important reason to ask whether trauma causes schizophrenia is the use of the phrase “brain disorder.” Schizophrenia has been characterized as a “brain disorder” along with other mental illnesses for decades. This is for good reason. Before this shift, it was assumed that serious mental illness was caused by a dysfunctional family - primarily the mother. We now know this is not true except in extremely problematic situations. But this theory caused harm to many families and justified resentment from mothers. Unfortunately, there are still remnants of this belief. Psychiatric research has shown that many symptoms of mental illness are related to differences in brain structure and functioning. Advocating for schizophrenia as a “brain disorder” has helped to prevent people from always blaming the family. It has also helped to move the blame away from the person - schizophrenia is not a character flaw, weakness, or other stigmatized judgment. The “brain disorder” explanation of mental illness has also been valuable for political advocacy, especially working toward mental health parity.
There are also problems with thinking about schizophrenia as a “brain disorder.” One problem with this thinking is that it leads us to assume that it cannot change 13,14. We assume that people with schizophrenia can only get worse, as if they had an untreatable tumor or late-stage Alzheimer’s. These assumptions create stigma about people with schizophrenia. These assumptions also create self-stigma - people with schizophrenia may believe their diagnosis amounts to a death sentence. These assumptions do not reflect reality. Most people with schizophrenia experience recovery and treatments help. Still, stigma from the outside and from within a person is a significant risk 15,16.
“Vulnerability-stress” is currently the best way to think about schizophrenia. It acknowledges genetic and brain vulnerabilities. It also recognizes that stress and a person’s environment contribute to causing both mental illness and recovery. It is not clear if using the vulnerability-stress model reduces stigmatized assumptions 17. But the vulnerability-stress model helps show how families and individuals can find new ways to make meaning out of life and deal with stress to live well with schizophrenia despite having vulnerability to its symptoms.
Family members may ask about trauma and schizophrenia because they feel blamed for their loved one’s mental illness. Families and individuals experience confusing emotions of anger, resentment, grief, guilt, and loss. Mental illnesses like schizophrenia happen to a person’s whole life. This includes family, and the impacts and anguish can be severe. Family members naturally wish they could protect their loved one from the anguish at the center of a diagnosis like schizophrenia. They wish they could prevent them from experiencing any more trauma. They wish they could go back in time and stop whatever traumas contributed to their loved one’s challenges. Researchers in the UK have documented many of these perspectives and the ways families and individuals heal 18. Sharing and allowing yourself to experience these difficult emotions and realities is part of healing.
If a family member caused significant trauma or is a risk for causing more trauma, there are cases where separation may be for the best. However, most family members who are asking this kind of question have not caused any severe trauma. Their loved one may accuse them of causing trauma. Or the family member may feel guilty for not having protected their loved one. Family support groups and training programs (such as Akin’s family program) help families process this grief and guilt and support loved ones more effectively. For an individual who has experienced severe trauma, their trauma is by definition unreasonable and difficult to understand or think about. However, some of the most effective psychotherapies available are those that help people process and understand severe trauma to take back their life 19-21.
While many people are aware of biological vulnerabilities to schizophrenia, most people are not aware of the significant causal role of stressors and trauma. This is a problem because it can lead people to believe there is nothing you can do to prevent or manage symptoms of schizophrenia or other types of psychosis. The opposite is true. Early intervention (before or around onset of symptoms) can prevent loss of functioning or worsening of symptoms for many people 9,10,22. There is also clear evidence that improving social determinants of health (such as access to housing or freedom from discrimination) could make a difference 23,24. For individuals, it is often helpful to get to know your own biological vulnerabilities and the role of past stressors or traumas. This often helps to understand and manage future stressors or traumas to carve a path toward recovery.
“No one cause” means no “one size fits all” treatment
For clinicians or researchers, I might have a slightly different answer to “Can trauma cause schizophrenia.” Trauma can cause schizophrenia, but you cannot assume that a person with schizophrenia has experienced significant trauma. It is not worthwhile to search for unknown severe trauma, which can instead be harmful. On the other hand, trauma is often ignored in treatment. It is critical to ask about and address trauma.
Providers may never ask about traumatic experiences. Or the relevance of trauma may be “overshadowed” by the schizophrenia diagnosis 25,26. People with schizophrenia often benefit from understanding traumas that have contributed to their mental health challenges. Medications are often helpful but not “enough” to facilitate recovery given how complex it can be. There are a wide variety of effective treatments beyond medication, including family-focused treatments and individual treatments for PTSD 16,20,22,27,28. Overall, it is important for clinicians to ask about trauma and conduct trauma-informed care 19.
Around one-third of people with serious mental illness like schizophrenia have posttraumatic stress disorder (PTSD). Having PTSD means that they continue to suffer from a past severe trauma. Trauma is still a risk after a person is diagnosed. Trauma and other stressors that happen to people with schizophrenia can make symptoms worse and prevent recovery. People with serious mental illness diagnoses like schizophrenia are at high risk for suffering violence, victimization, and other trauma 29. Tragically, many people experience trauma during treatment 30. Nonetheless, PTSD is rarely diagnosed or treated for people with schizophrenia 20,26.
Overall, many types of trauma are related to schizophrenia, and many people with schizophrenia continue to experience trauma. Still, schizophrenia in general is “caused” by a variety of factors often including trauma, genes, development, and environment. The impacts of serious mental illness are also widespread, including the family and community. However, most of the treatments available in many communities only focus on managing short-term risks and reducing psychosis symptoms. Treatment and recovery have to be holistic and account for the many problems and strengths that affect illness and recovery for an individual and their community 31.
Trauma is a stressor that can cause psychosis, schizophrenia, or other mental illness for a person who has some vulnerability to mental illness. It is more helpful to think of trauma and schizophrenia in terms of vulnerability-stress rather than reducing mental illness to the brain or biology. In some cases, severe trauma may cause mental illness in itself. People with mental illness are also at much higher risk to experience new traumas. Trauma is so common among people with diagnoses like schizophrenia that it cannot be ignored, and trauma-informed care is best practice. However, families and individuals do not benefit from digging for unknown traumas or ruminating over not having protected their loved one from trauma. Instead, we benefit from accepting the confusing and difficult emotions related to trauma. We also benefit from processing and talking about trauma in a safe space or seeking professional trauma-informed help. Providers must think beyond psychosis symptoms and avoid reducing treatment to what medications can do. Trauma is one of the areas that is too often ignored in treatment (and treatment funding), despite mandates for trauma-informed care.