Uncertainty Linked to Paranoia and Early Psychosis Across Mental Health Conditions

When life feels unpredictable, many people experience unease—but for some, this discomfort goes deeper.

A new study suggests that difficulty tolerating uncertainty may play a significant role in symptoms like paranoia and early warning signs of psychosis, not just in those with schizophrenia, but also in people with anxiety disorders and even the general population.

A new study by Jayne Morriss and Lyn Ellett, published in Psychology and Psychotherapy: Theory, Research and Practice (2025), explores how intolerance of uncertainty relates to paranoia and prodromal symptoms—early indicators of psychosis—across different mental health conditions.

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The researchers found that people who struggle more with uncertainty also report higher levels of paranoia and early psychosis symptoms, regardless of whether they have a schizophrenia-spectrum disorder, an anxiety disorder, or no clinical diagnosis.

Intolerance of uncertainty refers to a tendency to perceive ambiguous or unpredictable situations as threatening or distressing.

It’s been previously linked to anxiety and worry, but growing evidence suggests it may also be relevant to more severe mental health issues, such as paranoia—suspicion or mistrust of others—and psychosis, which can involve hallucinations or delusions.

The early stage of psychosis, known as the prodromal phase, may include subtle changes in thoughts, perceptions, and emotions, often occurring months before a full psychotic episode.

To better understand these relationships, the researchers surveyed 307 adults divided into three groups: individuals with a schizophrenia-spectrum disorder (103), those with an anxiety disorder (102), and a non-clinical comparison group (102).

Participants completed questionnaires measuring their intolerance of uncertainty, paranoia, prodromal symptoms, neuroticism, and a specific thinking bias known as “jumping to conclusions,” which describes the tendency to make hasty decisions without sufficient evidence.

The study revealed several key patterns.

People with schizophrenia-spectrum disorders and those with anxiety scored significantly higher on intolerance of uncertainty compared to the non-clinical group.

These two clinical groups also reported more severe paranoia and prodromal symptoms.

Importantly, greater intolerance of uncertainty was consistently linked to greater paranoia and prodromal symptoms across all three groups – even when researchers accounted for other psychological traits like neuroticism and the jumping-to-conclusions bias.

However, one exception emerged.

In individuals with schizophrenia-spectrum disorders, the connection between intolerance of uncertainty and paranoia disappeared when the thinking bias was taken into account.

This suggests that, in schizophrenia, the tendency to jump to conclusions may play a stronger role in fostering paranoid thoughts than uncertainty alone.

These findings have important implications. They suggest that intolerance of uncertainty may be a transdiagnostic factor—that is, a psychological process contributing to symptoms across different mental health conditions.

This means therapies that target how people respond to uncertainty, such as certain forms of cognitive-behavioral therapy (CBT), might be useful not only for anxiety but also for early psychosis or persistent paranoia.

“Targeting intolerance of uncertainty could help prevent the progression of symptoms in people at risk for psychosis,” the authors suggest, pointing to previous research showing that CBT can reduce uncertainty-related anxiety.

Their findings open the door to adapting these approaches for individuals with emerging psychotic symptoms or severe paranoia.

Still, the researchers caution against overgeneralizing.

The study was cross-sectional, meaning it looked at participants at one point in time, so it can’t confirm whether intolerance of uncertainty actually causes paranoid or psychotic symptoms.

Additionally, the sample relied on self-reported diagnoses and came from English-speaking countries, limiting its generalizability.

Further studies using clinical interviews and tracking people over time are needed to clarify whether reducing intolerance of uncertainty can directly improve mental health outcomes.

Despite these caveats, the study offers a compelling glimpse into how a common psychological trait—discomfort with not knowing—may underlie very different kinds of distress, from everyday anxiety to serious mental illness.

For people experiencing persistent suspiciousness, emotional changes, or unusual thoughts, addressing their response to uncertainty might be a promising step toward relief.

Citation

Morriss, J., & Ellett, L. Intolerance of uncertainty, paranoia, and prodromal symptoms: Comparisons between a schizophrenia spectrum disorder, anxiety disorder and non-clinical sample. Psychology and Psychotherapy: Theory, Research and Practice. https://doi.org/10.1111/papt.12599

Saul McLeod, PhD

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Editor-in-Chief for Simply Psychology

Saul McLeod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.


Olivia Guy-Evans, MSc

Associate Editor for Simply Psychology

BSc (Hons) Psychology, MSc Psychology of Education

Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.

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