How Do Traumatic Experiences Affect the Risk of Psychosis?

What you need to know

• Experiencing traumatic events increases the risk of developing psychotic disorders later in life
• Both interpersonal traumas (like violence) and non-interpersonal traumas (like accidents) contribute to this increased risk, but interpersonal traumas have a stronger effect
• A diagnosis of post-traumatic stress disorder (PTSD) is associated with higher risk of later psychotic disorders
• However, PTSD does not seem to fully explain the link between trauma and psychosis

Understanding psychotic disorders

Psychotic disorders affect about 3% of people at some point in their lives. These conditions involve a disconnect from reality, often including symptoms like hallucinations (perceiving things that aren’t there) and delusions (strongly held false beliefs). Schizophrenia is one well-known type of psychotic disorder.

These disorders can have a major impact on a person’s life and functioning. Current treatments help many people but are not always fully effective. To develop better prevention and treatment strategies, researchers are working to understand what factors contribute to the development of psychotic disorders.

The trauma-psychosis connection

Over the past decade, a growing body of research has pointed to traumatic experiences as an important risk factor for psychotic disorders. Trauma refers to extremely stressful, frightening, or distressing events. Researchers typically divide traumas into two main categories:

1. Interpersonal traumas: Events involving harm or threat from other people, like physical or sexual abuse, assault, or witnessing violence

2. Non-interpersonal traumas: Stressful events not directly caused by others, like serious accidents, natural disasters, or the death of a loved one

Most studies have focused on childhood trauma. However, traumatic events can occur at any point in life and may have cumulative effects over time.

A nationwide study in Sweden

To better understand the connections between trauma, mental health, and psychosis, researchers conducted a large study using health records from Sweden. They followed nearly 2 million people born between 1971 and 1990, tracking their experiences from age 16 onward.

The researchers identified traumatic events and mental health diagnoses recorded in the Swedish national health registers. They then used statistical methods to examine how these factors related to each other over time.

Key findings

Trauma increases psychosis risk

Both interpersonal and non-interpersonal traumas were associated with an increased risk of developing a non-affective psychotic disorder (NAPD). NAPD is a category that includes schizophrenia and related conditions.

The link was stronger for interpersonal traumas:

• Each additional interpersonal trauma was associated with about a 2-fold increase in NAPD risk
• Each additional non-interpersonal trauma was associated with about a 1.3-fold increase in NAPD risk

These effects remained significant even after the researchers accounted for many other factors that could influence psychosis risk, like family history of mental illness.

Trauma also increases PTSD risk

Not surprisingly, experiencing traumatic events also increased the likelihood of being diagnosed with post-traumatic stress disorder (PTSD). Again, interpersonal traumas had a stronger effect:

• Each additional interpersonal trauma was associated with about a 3.4-fold increase in PTSD risk
• Each additional non-interpersonal trauma was associated with about a 1.5-fold increase in PTSD risk

PTSD and psychosis are linked

People diagnosed with PTSD had a much higher risk of later being diagnosed with a psychotic disorder. After accounting for other factors, a PTSD diagnosis was associated with about an 8-fold increase in NAPD risk.

Trauma timing matters, but effects persist

The researchers also looked at whether the timing of trauma exposure made a difference:

• Trauma experienced in adulthood (after age 16) still increased psychosis risk, even when childhood trauma was accounted for
• The effects of trauma on psychosis risk remained significant even when the researchers only looked at psychotic disorders diagnosed 5 or more years after the traumatic event

This suggests that trauma can have long-lasting effects on mental health, and that experiences throughout life (not just in childhood) may contribute to psychosis risk.

Does PTSD explain the trauma-psychosis link?

One theory is that PTSD might be the primary pathway through which trauma leads to psychosis. In other words, trauma causes PTSD, which then increases psychosis risk.

To test this idea, the researchers used advanced statistical techniques to see if PTSD diagnoses could explain (or “mediate”) the relationship between interpersonal trauma and psychotic disorders.

Surprisingly, they found little evidence that PTSD diagnoses mediated this relationship. This suggests that while PTSD and psychotic disorders are related, the pathway from trauma to psychosis likely involves additional factors beyond just PTSD symptoms.

Limitations and considerations

While this study provides valuable insights, it’s important to keep a few limitations in mind:

• The study relied on diagnoses and events recorded in health registers. This means it may have missed traumas or mental health issues that weren’t reported to healthcare providers.

• The researchers couldn’t account for all possible factors that might influence psychosis risk.

• The study shows associations between trauma and psychosis, but can’t definitively prove that trauma directly causes psychotic disorders.

Implications for understanding and treating psychosis

Despite these limitations, the strong and consistent relationships observed in this large study suggest that trauma likely plays an important role in the development of psychotic disorders for many people.

The findings highlight the need to:

1. Recognize trauma as a significant risk factor for psychosis
2. Develop and study trauma-informed approaches to psychosis prevention and treatment
3. Consider both childhood and adult experiences when assessing psychosis risk
4. Look beyond just PTSD symptoms when thinking about how trauma might lead to psychosis

Conclusions

• Traumatic experiences, especially those involving interpersonal harm, increase the risk of developing psychotic disorders later in life
• This increased risk persists even years after the traumatic event
• While PTSD and psychotic disorders are related, PTSD alone doesn’t fully explain how trauma contributes to psychosis risk
• More research is needed to understand the complex psychological and biological pathways connecting trauma and psychosis