Hallucinations Not Predictive of Psychosis

Pam Harrison

October 15, 2015

UPDATED October 19, 2015 // Contrary to popular belief, hallucinations are not predictive of the presence of psychotic syndromes, because they are common in other conditions and are absent in many patients with schizophrenia, new research shows.

"Many patients who are having these clinical high-risk symptoms have a significant problem, either some sort of mood disorder or they're developing personality disorder or they have problems with high levels of stress or trauma, but only a minority of them will go on to develop psychosis," study investigator Diana Perkins, MD, MPH, University of North Carolina at Chapel Hill, told Medscape Medical News.

"And while our interventions to prevent psychosis, like psychotherapy, are relatively nonspecific, what we really want to know is what these patients' trajectories will be so that we eventually might be able to intervene and prevent progression to psychosis among those who are going to progress compared to those who are not."

The study was published online October 8 in Schizophrenia Research.

Not a Warning Sign

Study participants were from two cohorts of the North American Prodrome Longitudinal Study. All patients met criteria of psychosis-risk states, including attenuated psychotic symptoms syndrome, brief intermittent psychotic symptoms syndrome, and genetic risk and deterioration syndrome.

Cohort 1 included 296 patients for whom investigators developed a "classifier" that included items from the Scale of Psychosis–Risk Symptoms (SOPS) that best distinguished patients who experienced conversion to psychosis from those who did not.

SOPS comprises 19 symptoms in four domains; these include positive symptoms; negative symptoms; measures of disorganization; and general symptoms overall, such as impaired stress tolerance.

Among all of the items measured by SOPS, investigators sought a "risk prediction subscale" from SOPS to identify subsets of symptoms that best predicted which patients were most likely to experience conversion to psychosis. The Presence of Psychotic Syndrome (POPS) criteria were used to classify a patient as a "converter" to psychosis.

A second cohort, consisting of 592 patients, served as an independent test set following validation of distinguishing symptoms with the highest predictive ability in cohort 1.

Measured by POPS, the most important symptoms that described patients who underwent conversion to psychosis at 2-year follow-up were disordered or unusual thought content and suspiciousness or persecutory ideas.

Dr Perkins explained that disordered thought content is similar to delusions, the fundamental difference being that with disordered thought content, patients' insight is still intact.

"Patients know something odd is going on; their experience is unusual, so while they may have a sense that, for example, everybody in a restaurant is talking about them or looking at them, they have insight and awareness that it's not actually happening to them," she said.

These two key symptoms were followed by reduced ideational richness, defined in SOPS as difficulties following everyday conversations or engaging in abstract thinking, and trouble with focus and attention problems regarding distractibility and short-term memory ― both of which also distinguished those who experienced conversion from those who did not.

Using all four of the items on the subscale allowed better discrimination between those who converted and those who did not than using the two-item subscale, investigators note. However, the magnitude of the difference between the two subscales was small, and the clinical importance is yet to be undetermined.

"In contemporary research settings, the 2-item and 4-item subscales might have utility in identifying higher-risk subgroups in persons meeting Criteria of Psychosis–Risk Syndromes," investigators write.

For example, in the second test cohort of 592 patients, about one third of patients met the severity threshold, having a 2-year conversion risk of 30%.

This compared to a 2-year conversion risk of only 9% in the remaining two thirds of patients identified as being at lower risk for conversion to psychosis.

"I think this study shows we need to be emphasizing a person's thought process and appreciate that perceptual disturbances (hallucinations) may not be a specific early warning sign of psychosis risk," Dr Perkins said in a statement.

"And I believe [these findings] will affect how we develop our diagnostic system in the future for people who are at high risk for psychosis."

Need to Intervene

Asked by Medscape Medical News to comment on the study, Anthony Lehman, MD, senior associate dean, Office of Clinical Affairs, and professor of psychiatry, University of Maryland School of Medicine, College Park, said there really is a need to better distinguish who among high-risk patients will convert to a serious mental illness and who will not.

"We need to identify these high-risk patients in a more systematic way so that we can intervene with them appropriately hopefully before they become diagnosable with a serious mental illness," Dr Lehman said.

"And I think this study advances our understanding of who will convert and who won't, to some extent."

Dr Lehman noted that the new findings make a lot of sense to him.

"The core impairment in schizophrenia is really the cognitive dysfunction, meaning information processing problems, short-term memory problems. And these symptoms correlate pretty much with the four symptoms these authors identified in their analysis," Dr Lehman said.

"And being able to distinguish from a clinical standpoint whether and when to begin a medication and when to hold off would be very helpful."

The study was funded by the National Institute of Mental Health. Neither Dr Perkins nor Dr Lehman have disclosed any relevant financial realtionships.

Schizophr Res. Published online October 8, 2015. Abstract


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