Comorbid diagnoses in patients meeting criteria for the schizophrenia prodrome

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Abstract

While schizophrenia is often associated with a variety of concurrent psychiatric symptoms, little attention has been paid to the prevalence of psychiatric comorbidity in prodromal patients. The current study examines the presence of comorbid current and lifetime psychiatric conditions in prospectively identified prodromal patients. The results suggest that like their schizophrenic counterparts, prodromal patients experience a wide array of comorbid psychiatric syndromes, with the most common being Major Depressive Disorder and Cannabis Dependence. Results also suggest that Cannabis Dependence may be more common among prodromal versus help-seeking control patients. These findings lay the groundwork for further examination of the role that comorbid conditions play in the development, course, and severity of schizophrenia.

Introduction

Schizophrenia is a common and devastating mental illness that typically arises during adolescence and young adulthood (McGlashan and Fenton, 1993). Despite recent advances in treatment, most patients remain chronically disabled throughout their lives. The disability has been attributed not only to the symptoms inherent to schizophrenia, but also to the comorbid psychiatric syndromes from which more than 50% of patients with schizophrenia suffer (Cassano et al., 1998, Fenton, 2001, Green et al., 2003, Strakowski et al., 1993).

Historically, our understanding of the early course of schizophrenia primarily has been limited to retrospective assessment after the onset of the psychotic phase (an der Heiden and Hafner, 2000, Hafner et al., 1998a, Hafner et al., 1998b), supplemented by prospective studies (Chapman et al., 1994, Poulton et al., 2000). Such assessments have offered substantial data on the presence and development of attenuated psychotic-like symptoms during the prodromal phase. Published reports also have suggested that the early course of illness is marked by nonspecific clinical states, such as depressive, negative, and anxiety symptoms (an der Heiden and Hafner, 2000, Meyer et al., 2005, Turnbull and Bebbington, 2001).

Current diagnostic assessments based on attenuated psychotic-like symptoms have enabled the prospective identification of persons in the prodromal phase of schizophrenia (McGlashan et al., 2001, Miller et al., 2002, Miller et al., 2003a, Rosen et al., 2002). Investigators are now focusing on developing strategies to further characterize prodromal syndromes (Meyer et al., 2005, Yung and McGorry, 1996). While patients with schizophrenia are known frequently to meet criteria for co-occurring syndromes, diagnostic comorbidity during the developing (i.e. prodromal) phase of illness remains relatively undescribed.

Several studies have begun to touch upon the issue. In one published study, researchers found that help-seeking prodromal patients had a rich history of contact with psychiatric services prior to their having been identified as at-risk for emerging schizophrenia (Preda et al., 2002). Other researchers have identified comorbid lifetime disorders (Lencz et al., 2004), comorbid baseline symptomatology (Meyer et al., 2005, Yung et al., 2003), comorbid substance use (McGlashan et al., 2003, Woods et al., 2003) and comorbid outcome psychiatric diagnoses (Yung et al., 2003), among patients at high-risk for conversion to psychosis. None of these studies, however, utilize structured interview methods to examine possible differences in lifetime diagnoses that may exist between help-seeking prodromal patients and appropriate controls. Such information may extend our ability to identify young people at high risk for psychosis and enhance our knowledge on the role that concomitant clinical symptoms have on the emergence of psychosis.

The current study aimed to extend existing knowledge by examining the presence of comorbid current and lifetime psychiatric conditions in prospectively identified prodromal patients and help-seeking controls. The control group consisted of those patients who upon evaluation did not meet criteria for an at-risk prodromal syndrome.

Section snippets

Study population

Patients in the current study were those consecutively evaluated between February 1998 and December 2003 at the Prevention through Risk Identification, Management, and Education (PRIME) Research Clinic (New Haven, CT, USA). All patients were recruited through an extensive referral network with community health care providers, student counselors, clergy, or members of family advocate organizations (Miller et al., 2003b).

Eligible patients were: treatment seeking persons ages 12–45 years,

Sample characteristics

Between February 1998 and December 2003, 171 patients were evaluated at PRIME. Of the 171, 107 (63%) met inclusion criteria for the current study. Of the 107 eligible patients, 49 did not participate in the current study: 17 (16%) refused participation, 26 (24%) were unable to be located for comorbidity interview despite recruitment efforts, 4 (4%) were missing data for their baseline prodromal status, and 2 (2%) were deceased (n = 1) or incarcerated (n = 1).

Twenty-nine prodromal patients (14 (48%)

Discussion

Results of the current study indicate a high presence of both lifetime and current comorbid psychiatric syndromes in prospectively identified prodromal patients. Close to 60% of prodromal patients in this study experienced a lifetime depressive disorder and close to 50% experienced a lifetime major depressive disorder. Earlier research has indicated a similar high prevalence of psychiatric comorbidity in patients with schizophrenia (Cassano et al., 1998, Green et al., 2003, Strakowski et al.,

Acknowledgements

This research was supported by a USPHS grant U01 MH66160 (SWW) and by the Donaghue Medical Research Foundations' Early Schizophrenia Initiative (SWW).

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