Combined screening could detect early schizophrenia

Schizophrenia is a long-term mental disorder with a genetic component that involves abnormal interpretation of reality, which can manifest as hallucinations, delusions, and disordered thinking and behavior. Studies reveal that subtle indications of the disease can be identified long before full-blown psychosis develops. Early diagnosis could help doctors prescribe treatments to prevent the disease's progression.

Screening tools that are commonly used for this purpose involve self-assessments, since the initial symptoms are experienced rather than obvious from people's behaviors. These include subjectively experienced disturbances of perception, cognition, language, motor function, will, initiative, energy level and stress tolerance.

However, used on their own, currently available self-assessments aren't perfect, often producing exaggerated false positive results.

A team of researchers from Universiti Teknologi Mara and Universiti Sains Malaysia developed a two-stage process to screen two groups of people: at-risk relatives of people with schizophrenia and a corresponding sample from the general population. The first stage of the process involved using two common early schizophrenia screening questionnaires on all participants, which produced 190 positive results (29%) from the total number of participants (660) in both groups. Interestingly, a larger number of positive results appeared in the general population (36%) compared to the at-risk participants (21.5%).

However, when the 190 participants who tested positive were given a third questionnaire, only 29 tested positive, nine of whom were categorised as having what is known as ultra-high risk psychosis. Previous research has shown that 30-50% of individuals diagnosed with ultra-high-risk psychosis progress to full-blown psychosis. The remaining positively testing participants were diagnosed through the screening process as having sub-threshold psychosis, the symptoms of which normally disappear over time.

Researchers believe there are two explanations for the very high false positive results from the first stage of the screening process. At-risk individuals might be underestimating their symptoms because of their relative separation from reality, while people from the general population might overestimate their experiences or misinterpret them.

The researchers conclude that clinical assessments or re-interviews should be mandatory following positive self-report questionnaires to eliminate false positive individuals. They also recommend using combinations of self-assessment tools to detect different stages of early psychosis.