27 May 2009. Children and teenagers who experience psychotic-like symptoms in the absence of diagnosable psychosis comprise a group at high risk of developing schizophrenia, according to speakers at a symposium of the 2009 International Congress on Schizophrenia Research in San Diego on 29 March. The symposium, organized by Mary Cannon of the Royal College of Surgeons in Ireland, Dublin, and Jack Jenner of University Medical Center Groningen, in The Netherlands, brought together researchers from Europe and Australia, who described this group of youngsters, explored how best to evaluate them, and examined risk factors for psychotic-like experiences.
The nature of “psychotic-like” experiences was described by Ian Kelleher, from the Royal College of Surgeons in Ireland, Dublin, who spoke of a girl who reported hearing the sound of her own angry thoughts coming from outside her head twice a year for two years. Another heard strange-sounding girls’ voices and believed that others were talking about her. About once every six months, she felt chilled and thought that a ghost was passing through her. A boy sometimes heard the voices of friends from his old school shouting unintelligible things all at once; he would suspect that someone was following him.
For centuries, adults have known that young people experience these kinds of symptoms, said session chair Mary Cannon. Her talk noted that estimates of the prevalence of these symptoms vary widely, depending on the assessment method used, and that studies based on self-report questionnaires disagree the most. She collaborated on a new systematic review that estimates that 16 percent of children and adolescents experience auditory hallucinations, one type of psychotic-like experience.
Cannon and others have examined risk factors for experiencing these symptoms, as well as other deficits in these at-risk young people. For instance, a study by Kelleher, Cannon, and others found that teenagers who reported psychotic symptoms were more likely to have been subjected to childhood physical abuse and domestic violence; they were also more likely to have bullied and been bullied as children (see SRF related news story; SRF news story; SRF news story).
Other deficits may accompany psychotic-like symptoms, according to additional work by Cannon and colleagues. They connected subclinical psychotic symptoms to neuromotor impairment and deficits in language comprehension in teenagers. In a study that measured event-related potentials, they found that children at risk of developing psychosis seem to process language differently than their peers do.
Following up on Cannon’s point about self-report questionnaires, Kelleher presented findings from work they did together to test the validity of such questionnaires for identifying young people who have psychotic-type experiences. Noting that research had not established the sensitivity and specificity of screening questions for this purpose, they decided to examine them in 334 11-12-year-old children. The seven items the researchers looked at asked subjects whether they ever had specific experiences, such as feeling like they had extra-special powers or had messages sent solely to them via television or radio. The study compared responses to the screening questions with data from semi-structured interviews that were based on the Schedule for Affective Disorders and Schizophrenia for School-Aged Children.
In response to screening questions, 38 percent of the children replied “yes, definitely” and 35.4 percent said “maybe” to having had one or more kinds of psychotic-like experiences. In the interviews, 17 subjects reported “definite” psychotic-like experiences and five reported “possible” ones. Of the subjects who reported definite symptoms during the interview, 71 percent reported auditory hallucinations, the most common type of psychotic-like experience, and 59 percent reported suspiciousness or persecutory ideas.
Kelleher found that a number of the screening questions showed good sensitivity and specificity; the results support their use as a quick tool for identifying teens with psychotic-like experiences in the general population. A question on auditory hallucinations, in particular, performed well at predicting who reported psychotic-like experiences of any kind during the interview.
Kristin Laurens of Kings College London, in England, wondered whether children who have psychotic-like experiences and other suspected antecedents of schizophrenia would also show cognitive impairment. Such impairments commonly exist in full-blown schizophrenia and, to a lesser extent, in the prodromal phase of the illness. In addition, children with a predisposing family history who later develop schizophrenia perform worse on IQ tests and cognitive tasks than do their peers in school.
Based on past research, Laurens identified the following triad of schizophrenia antecedents: caregiver reports of abnormal speech or motor development in the child; caregiver reports of social, emotional, or behavioral problems in the child; and child reports of psychotic-like experiences. In her study of 6,008 9-12-year-olds and 1,261 caregivers, Laurens found that 63 percent of boys and 56 percent of girls reported being certain of having had at least one psychotic-like experience. In contrast, only 11 percent of caregivers reported that the child in their care had certainly experienced one or more.
Compared to typically developing children, those who showed the three antecedents of schizophrenia performed worse on cognitive tests, particularly on tests that tapped verbal working memory and inhibitory aspects of executive functioning. Laurens noted that these deficits stop short of those seen in patients with first-episode schizophrenia, but appear similar in magnitude to those found in young people who seek clinical attention during the prodrome.
Two talks probed specific types of psychotic-like experiences. In the first, Agna Bartels of University Medical Center Groningen, in The Netherlands, focused on voice hallucinations in children ages 7 and 8. In the population-based sample, 9 percent of subjects reported auditory hallucinations, unbeknownst to most of their parents. Most of the children experienced little distress or disruption from them, but 15 percent reported intense suffering and 19 percent said that the hallucinations severely hindered their thinking. The odds of hearing voices doubled for children whose mothers had had an infection while pregnant with them (OR = 2.07, 95 percent confidence interval 1.04-4.05) (see SRF related news story; SRF news story) and increased slightly if the child’s motor development had been delayed (OR = 1.22, 95 percent confidence interval 1.02-1.46).
In general, Bartels found little evidence to tie these hallucinations to current behavioral problems in the children, except for one domain on the Child Behavior Checklist. Specifically, children with severe auditory voice hallucinations experienced more somatic complaints than those with either mild or no such hallucinations (OR = 1.25, 95 percent confidence interval 1.03-1.52).
Currently, Bartels is conducting a follow-up study of the same children. Preliminary findings suggest that the voices, more often than not, disappear: only about a fourth of subjects who experienced auditory voice hallucinations at baseline were still experiencing them at age 12 to 13.
James Scott of the Royal Children’s Hospital in Brisbane, Australia, focused on psychotic-like experiences that resemble delusions. He examined whether psychopathology during childhood and adolescence would predict delusions in adulthood. To find out, he used data from the Mater-University of Queensland Study of Pregnancy, which followed 7,223 mothers and their offspring for 21 years. Information on psychopathology came from mothers’ ratings of their children’s emotional and behavioral problems at ages 5 and 14 and from the youngsters’ own ratings at age 14. In addition, at age 21, subjects answered questions about delusions on a screening questionnaire.
Scott found that emotional and behavioral problems at ages 5 and 14 predicted delusion-like experiences at age 21. When he looked closely at the trajectories, he found that psychopathology that persisted or appeared anew between ages 5 and 14 strongly predicted delusions in adulthood. Furthermore, subjects who had frequent visual or auditory hallucinations at age 14 experienced more delusion-like ideas at age 21 (OR for auditory hallucinations = 4.84, 95 percent confidence interval 2.08-11.26; for visual hallucinations OR = 8.68 (95 percent confidence interval 2.57-29.30). Looking at the big picture, Scott said that his findings bolster the notion that delusion-like experiences span a continuum (see SRF related news story) and highlight the need for preventive efforts to stop people from moving further along the path to psychosis.
In conclusion, discussant John McGrath of the University of Queensland in Brisbane, Australia, said that although some people still see psychotic-like experiences as “noise” that stems from a misunderstanding of the screening questions and impedes diagnosis, these findings suggest otherwise. He noted that such experiences may predict not only psychosis, but also other outcomes, such as depression and anxiety.—Victoria L. Wilcox.