In a general population sample of 212 school-going adolescents, we found that up to 8% fulfilled criteria for diagnosis of a current prodromal risk syndrome. The findings of the current work suggest that there are many prospectively identifiable individuals with risk syndromes in the community who have not presented to clinical services. What proportion of these individuals would ultimately present to services is unknown. However, while the overwhelming majority of cases of new onset psychosis have been established to be preceded by a prodromal period,29–31
only a minority of the population-wide incidence of psychosis emerge in patients from prodrome risk syndrome clinics, which suggests that many such individuals will not clinically present prior to illness onset.
APSP, as described, differs from the proposed DSM-V diagnosis of attenuated psychosis syndrome in Criterion D (“distress/disability/treatment seeking,” see ). However, the majority of adolescents meeting criteria for APSP reported distress as a result of their symptoms, and this group demonstrated significantly poorer functioning on the Children’s Global Assessment Scale. BIPS diagnoses, which usually constitute a relatively small proportion of patients seen in prodromal risk syndrome clinics, were present in 40% of all risk syndromes in the current study. Interestingly, in the clinic, risk for psychosis has been demonstrated to be particularly high for patients with BIPS, with a faster onset of psychosis compared with young people with APSP.32
It is possible that fewer BIPS patients will present clinically during the prodrome and are more likely to present for the first time during first-episode psychosis due to what appears to be a shorter prodromal period. It is also possible, because the symptoms are “brief” and “intermittent,” that patients believe their symptoms have resolved and are, as a result, less likely to seek help. Further research will be necessary to understand this difference between the clinic and the community.
Nonpsychotic psychiatric disorders were present in a large majority of adolescents with prodromal risk syndromes, consistent with research on clinically presenting individuals.33
Rosen et al,34
for example, reported that in a sample of clinically presenting individuals who met criteria for a prodromal risk syndrome, 76% had at least one diagnosable lifetime Axis 1 disorder. Svirskis et al,35
similarly, reported that over 90% of help-seeking individuals who met criteria for a prodromal risk syndrome had at least one comorbid disorder. Depressive disorders were the most common diagnosis in both studies, as in the current report. Lencz et al,36
using the same diagnostic instrument as the current study to assess for Axis-1 psychopathology in a sample of putatively prodromal help seekers, found MDD to be the most common diagnosis, followed by attention deficit/hyperactivity disorder, in keeping with our own community findings.
There are a number of implications of this research in relation to the proposed DSM-V diagnosis of attenuated psychosis syndrome. Findings from the current study that might support this diagnosis include that (1) a large majority of the individuals identified are distressed by their symptoms; (2) this group demonstrates significantly poorer global functioning; and (3) the majority of these adolescents have other diagnosable psychopathology that suggests that they as a population are truly in need of care. On the other hand, the findings of the current study also raise a number of concerns or limitations with regard to creation of an attenuated psychosis syndrome diagnosis, including that (1) the proposed diagnostic criteria are applicable to a relatively large proportion of adolescents, meaning that, following publication of DSM-V, many young people could suddenly be imposed with a stigmatizing diagnosis that they did not previously have; (2) we do not know the relative risk for psychosis among this group since longitudinal community research has not been conducted. Given the high prevalence of the syndrome, however, it is unlikely to approach the level of risk observed in help-seeking samples reported on to date; thus, we risk greatly increasing the rate of false positives; (3) since the majority of these individuals already have psychiatric disorders, there would not, in most cases, appear to be a major financial barrier to receiving psychiatric treatment in healthcare systems that require a formal diagnosis for insurance purposes; (4) the proportion of adolescents who fulfill criteria for a risk syndrome varies greatly depending on how “disability” is interpreted in terms of the degree of functional decline, something that is not currently specified in the proposed criteria; and (5) attenuated psychosis syndrome may be a misnomer for a syndrome that is, in fact, associated with a wide range of (nonpsychotic) disorders.
It is important to note that none of the participants in the current study, despite meeting criteria for prodromal risk syndromes, had presented to a prodrome or other healthcare clinic and so none of the participants can be considered “help seekers” in the same way as individuals who have been reported on to date in clinic-based research. Why some individuals who meet risk syndrome criteria present to clinics while others do not is unclear and will require further research. There are many possible reasons for this. As already speculated, given the high proportion of BIPS in the current community study compared with the proportion of BIPS in clinic-based studies, it is possible that young people with BIPS are less likely to present to the clinic. The young age of participants in the current study may also be a contributing factor. Although, in our experience, even at this age, young people are very aware that these experiences are unusual, it is possible that younger individuals are less likely to attend their doctor or other health professional compared with older teenagers and young adults. Education around psychotic symptoms and psychosis risk syndromes may also be a factor. Addington et al,37
for example, showed that, following an extensive community education program, referrals to prodrome services increased. Thus, a lack of community education and confusion about “where to turn for help” with these unusual experiences may play a role in nonpresentation. There may be multiple other differences between help-seeking and nonhelp seeking individuals with prodromal risk syndromes. Further cross-sectional and longitudinal research comparing clinical and community samples will be necessary to address this question.
Strengths and Limitations
The general population sampling method used in the current study is the major strength, which allowed us to estimate the population prevalence of prodromal risk syndromes/at risk mental states. In addition, the approach used in the current study allowed us to investigate psychopathology and global functioning in very early stages of psychosis risk—earlier even than clinically presenting risk syndrome cases. A limitation is that the standard SIPS interview instrument was not used; rather the K-SADS instrument was altered to include SIPS questions on positive symptoms from sections P1 to P5. Thus, it might be argued that this could result in underestimation of the true prevalence of prodromal risk syndromes. While we surveyed a relatively large number of adolescents, a relatively small proportion was brought to interview, introducing the risk of ascertainment bias, whereby individuals with a personal or family history of disorder may be more likely to agree to participate, thus self-selecting for increased rates of the disorder under study. However, we do not believe this to be the case in the current study for a number of reasons: (1) adolescents who attended the full interview study did not differ from the larger surveyed school sample from which they were drawn in terms of symptoms of general psychopathology, as measured by the SDQ, or in terms of psychotic symptoms, as measured by the APSS; (2) only 1.3% of participants had a first-degree relative with a history of psychotic illness, suggesting that families with psychosis were not more likely to participate; and (3) the prevalence of mental disorders was very similar to previous epidemiological work both nationally and internationally.38,39
Participants were also representative of the general population in terms of ethnicity and SES. Nonetheless, further work to confirm our findings will be valuable.
It is important to note that research to date suggests that psychotic symptoms are more prevalent in early compared with later childhood. In a meta-analysis of population-based studies on the prevalence of psychotic symptoms in child and adolescent populations, we found that psychotic symptoms were more common in younger (ages 9 to 12 years) compared with older (ages 13 to 18 years) children.40
Thus, research in later adolescence, when psychosis risk is highest, might not find an equally high prevalence of prodromal risk syndromes compared with the younger population assessed in the current study. Further research among different age groups is necessary to address this question.