Can trauma cause schizophrenia?

What is schizophrenia?

Schizophrenia is considered a lifelong mental illness requiring ongoing treatment to manage its chronic symptoms. It belongs to a class of mental health conditions labeled as psychotic disorders.

To be diagnosed with schizophrenia, one or more of the following positive symptoms must be present more often than not for at least one month ^[1]:

• Delusions - Fixed beliefs not based on reality
• Hallucinations - Sensory experiences not based on reality
• Disorganized speech - Incoherent speech or derailment from topics 

Additional symptoms of schizophrenia may include negative symptoms ^[1]:

• Disorganized behavior 
• Catatonic behavior 
• Diminished expression of emotions  
• Avoidance of goal-directed or self-initiated behavior 

To be diagnosed, a person must experience at least two of the symptoms above.

Schizophrenia can be manageable with ongoing treatment through medication management and psychotherapy.

Can trauma trigger schizophrenia?

Current research does suggest that childhood trauma can trigger schizophrenia in adulthood and that experiencing psychological trauma as an adult worsens schizophrenia symptoms for those already experiencing the disorder.

For a long time, experts have known that there is a genetic link to the development of schizophrenia. Longitudinal studies strongly show that those with a first-degree relative diagnosed with schizophrenia are much more likely to develop the disorder.

Not everyone with a family history of this disease develops it. Environmental stress plays a considerable role in any mental illness development.

The diathesis-stress model, which is one model used in understanding how mental illness develops, suggests that stressors can trigger the symptoms of schizophrenia for those who are already predisposed to the condition. Furthermore, stress can worsen the symptoms of schizophrenia when those symptoms already exist. 

Adverse childhood experiences, or childhood traumas, can be considered a form of severe stress. Experts continue to learn how adverse childhood experiences, such as physical abuse, neglect, or sexual abuse, affect the developing brain and may lead to physiological changes within the biological system.

What constitutes childhood trauma? Exposures to long-term environmental stress during the developmental years are classified as childhood trauma. These stressors include ^[5]: 

• Losing a parent to death or estrangement
• Ongoing substance abuse in the home
• A family member in the household with active mental illness 
• Domestic violence in the home 

Childhood trauma also includes:

• Physical neglect
• Emotional neglect
• Emotional abuse
• Physical abuse
• Sexual abuse

One study found that specific symptoms of psychosis correlated with certain childhood experiences. More specifically, this study found associations between ^[6]:

• Childhood sexual abuse and hallucinations
• Institutional care and paranoid beliefs
• Physical abuse and hallucinations with paranoid beliefs

They also found that the more adverse experiences endured during childhood, the higher the likelihood of experiencing a psychotic episode ^[6].

One meta-analytic review found that if childhood adverse experiences were removed from the population studied, those experiencing psychotic symptoms would drop by 33% ^[8].

While there is a relationship between childhood trauma and psychotic symptoms, it is important to remember that correlation does not equal causation. Correlation does indicate there is a relationship between trauma and the development of schizophrenia, but there is not enough evidence to say that trauma directly causes schizophrenia. 

Schizophrenia vs PTSD

Schizophrenia and post-traumatic stress disorder (PTSD) can present similarly.

For instance, the flashbacks that can occur with PTSD may be confused with hallucinations because of their intensity. Hypervigilant behaviors that go along with PTSD may also present as paranoid behavior ^[1].

The key difference between these two psychiatric disorders is that a known traumatic experience has occurred, and that flashbacks and hypervigilance are the result of the traumatic experience in PTSD. For those with schizophrenia, the psychotic symptoms are not a direct result of the trauma and are not based on reality.

Schizophrenia and PTSD may occur comorbidly. Research is beginning to show just how common this comorbidity is.

One study of patients with schizophrenia showed rates of lifetime PTSD for those in the study to be 44.3% ^[3]. Another study found that in a population of community mental health consumers with schizophrenia, there was a prevalence rate of 91% who had experienced a traumatic event ^[2].

These findings reiterate the need for continued research into how traumatic experiences impact rates of mental illness such as schizophrenia.

Stress exacerbates mental health symptoms already present, including those of schizophrenia and other psychotic disorders. A traumatic experience occurring after schizophrenia onset is highly likely to worsen schizophrenia symptoms and may lead to an additional diagnosis of PTSD.

What else can cause schizophrenia?

There is not one single cause of schizophrenia. Whether or not someone becomes ill with this mental health disorder depends on many factors.

There is a strong genetic link to schizophrenia development. People with a parent or other first-degree relative with the condition are approximately 6 times more likely to develop it. This risk drops to being 2 times more likely if there is a second-degree relative with the disorder, such as a grandparent ^[4]. 

Research also shows a link between abuse of certain substances, including marijuana and methamphetamine, for those predisposed to the disorder. 

Exposures while in the womb may also play a role in schizophrenia. Malnutrition, for example, has been linked to an increased risk of schizophrenia ^[7].