Liam Davenport

April 04, 2016

FLORENCE, Italy — Speech illusions elicited in an experimental setting may point to vulnerability to psychosis, conclude Danish researchers, who suggest that auditory hallucinations may be due to dysregulation in the processing of sensory input driven by negative affect.

Research presented here at the Schizophrenia International Research Society (SIRS) 2016 Biennial Meeting showed, for the first time in children, that speech illusions experienced during the white noise task are significantly associated not only with auditory hallucinations but also negative affect.

Martin Rimvall, a medical student at the Child and Adolescent Mental Health Center, Mental Health Services, Glostrup, Denmark, who presented the research, said that this negative affect may drive alterations in top-down processing, leading to speech illusions.

Bottom-up processing deals with information received from sensory organs, whereas top-down processing consists of experiences that arise from internal expectations and interpretations.

"Hallucinations have been suggested to arise as a consequence of imbalance between these," he said.

Rimvall explained that the white noise task detects altered top-down vs bottom-up processing, as well as the attribution of affective salience.

The white noise task consists of exposure to three types of stimuli: clear speech, barely audible speech, and white noise only. The responses to white noise can be "no speech heard," "uncertain," "neutral voice," "positive voice," and "negative voice." For the current study, "uncertain" and "no speech heard" were grouped together as an absence of speech illusion; the remaining three were grouped as a speech illusion experience.

"If you had two or more of these experiences, you were regarded as someone experiencing speech illusions during this test, and if you heard either at least one positive or at least one negative voice, you were considered as having effectively salient speech illusions," Rimvall noted.

Processing Dysregulation

Previous research in older patients has indicated that speech illusions experienced while performing the task, particularly those with affective salience, are associated with psychotic disorders and with positive schizotypy in control participants.

The team studied participants in the Copenhagen Child Cohort, which has followed 6090 children from birth. For the current analysis, face-to-face interviews were conducted with 1632 children. The white noise task, using 36 stimuli instead of the standard 75, was administered to 1486 individuals.

The investigators found that 145 (9.8%) of the children experienced speech illusions, and that 102 (6.9%) experienced speech illusions with affective content, whether positive or negative. Initial analysis suggested that speech illusions were associated with lower IQ and sex, although this relationship was not significant.

Analysis revealed that hallucinations occurring in the past month were significantly associated with speech illusions on the white noise task (odds ratio, 2.05). Negative affect during the last month and lifetime negative affect were also associated with speech illusions (odds ratios, 2.01 and 1.80, respectively). These findings held after taking into account sex and estimated IQ.

There were no associations between speech illusions and delusions, a family history of psychosis, and hyper theory of mind.

Rimvall concluded that speech illusions, particularly those with affective salience, are common in children and are associated with negative affect, suggesting that there is a dysregulation in the top-down processing of sensory inputs, driven by negative affect.

The fact that the speech illusions were also associated with hallucinations but not delusions prompted him to suggest that these have separate mechanisms. The findings, he said, support the notion that there is an affective pathway from speech illusions to psychosis, raising the question as to whether children who experience speech illusions are at an increased risk of transitioning to psychotic disorder.

Psychosis Precursor?

Session chair Annegien Bartels-Velthuis, PhD, University of Groningen, University Medical Center Groningen, the Netherlands, believes that psychotic experiences such as auditory hallucinations might be a precursor not only for psychotic disorders or schizophrenia "but also for anxiety and depression."

Dr Annegien Bartels-Velthuis

She told Medscape Medical News that the study by Rimvall and colleagues "confirmed that there was an affective pathway in white noise, via the association with hearing voices, so I think that would be the link between them."

Dr Bartels-Velthuis emphasized, however, that the findings need to be replicated in larger studies and that it is "too soon to say we can detect future psychotic patients just based on the white noise task."

The important question, she said, is, "Why are there are some people who are being traumatized, hear voices, have anxiety and depression, but do not make the transition to a psychiatric disorder, whereas others with the same symptoms do?"

Other research presented at the session by Dr Bartels-Velthuis, and published online by Acta Psychiatrica Scandinavica last month, investigated the persistence of auditory vocal hallucinations (AVHs).

The investigators followed 293 persons aged 18 to 19 years and found that at age 6 years, the persistence of AVH was 18.2%; it was 6.2% at 11-year follow-up. AVHs at the final follow-up were linked to psychotic experiences, psychopathology, and traumatic events; persistent AVHs were associated with traumatic events and a higher risk for posttraumatic stress disorder.

Important Implications

Summarizing the presentations, Pia Jeppesen, PhD, Child and Adolescent Mental Health Center, Mental Health Services, Glostrup, Denmark, said the findings have some "very important implications" for how psychotic experiences, such as auditory hallucinations, are conceptualized and how they fit into current models of developmental psychopathology.

Although she believes that the presence of psychotic experiences should be assessed and "should alert the clinician to the increased severity of the nonpsychotic psychopathology," the lack of specificity of the risk factors in correlation with psychotic experiences "speaks against any kind of screening or early detection and treatment...per se."

She said that the strategy should be "more like watchful waiting" and that the risk for stigmatization should be avoided, given the fact that "talk of psychosis" can be "speculative."

Following the session, Dr Jeppesen, who supervised Rimvall's research, expanded on the idea of watchful waiting in this population and on the role the white noise task could play.

Noting the link between AVHs and nonpsychotic psychopathologies revealed by Dr Bartels-Velthuis, Dr Jeppesen told Medscape Medical News: "Down the road, [the task] might go into a profile of other measures that you could use in the clinic, but I don't think you would ever find one measure.

"What is really important, I think, is that, when you look at this very-early-stage developmental vulnerability for hearing voices when none are present...we're really looking at a very isolated mechanism that may or may not prove to be predictive in the long run," she added.

"At this stage, it's a way of studying the mechanism. We can say: 'Okay, there might be something going on with the top-down processing of stimuli at this early age.' "

Financial support for the study was provided by the Lundbeck and Tryg Foundations. The investigators have disclosed no relevant financial relationships.

Schizophrenia International Research Society (SIRS) 2016 Biennial Meeting: Presented April 3, 2016.

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