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Review
. 2009 Apr;109(1-3):24-37.
doi: 10.1016/j.schres.2009.01.016. Epub 2009 Feb 15.

Endophenotypes in schizophrenia: a selective review

Allyssa J Allen  1 , Mélina E Griss, Bradley S Folley, Keith A Hawkins, Godfrey D Pearlson
Affiliations
Review

Endophenotypes in schizophrenia: a selective review

Allyssa J Allen et al. Schizophr Res. 2009 Apr.

Abstract

Background: Given the wealth of data in the literature on schizophrenia endophenotypes, it is useful to have one source to reference their frequency data. We reviewed the literature on disease-liability associated variants in structural and functional magnetic resonance images (MRI), sensory processing measures, neuromotor abilities, neuropsychological measures, and physical characteristics in schizophrenia patients (SCZ), their first-degree relatives (REL), and healthy controls (HC). The purpose of this review was to provide a summary of the existing data on the most extensively published endophenotypes for schizophrenia.

Methods: We searched PubMed and MedLine for all studies on schizophrenia endophenotypes comparing SCZ to HC and/or REL to HC groups. Percent abnormal values, generally defined as >2 SD from the mean (in the direction of abnormality) and/or associated effect sizes (Cohen's d) were calculated for each study.

Results: Combined, the articles reported an average 39.4% (SD=20.7%; range=2.2-100%) of abnormal values in SCZ, 28.1% (SD=16.6%; range=1.6-67.0%) abnormal values in REL, and 10.2% (SD=6.7%; range=0.0-34.6%) in HC groups.

Conclusions: These findings are reviewed in the context of emerging hypotheses on schizophrenia endophenotypes, as well as a discussion of clustering trends among the various intermediate phenotypes. In addition, programs for future research are discussed, as instantiated in a few recent large-scale studies on multiple endophenotypes across patients, relatives, and healthy controls.

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Conflict of interest statement

Conflict of Interest None of the authors have a conflict of interest to report.

Figures

Figure 1
Figure 1
Median effect sizes for each endophenotype are plotted with 95% CI. Outliers (denoted by “o”) and extreme cases (denoted by “*”) are labeled by author and year. Note: Outliers were included in main effects summarization tables.
Figure 2
Figure 2
Average percent abnormal for each endophenotype category. The yellow line represents the expected percent abnormal (2.5%). Note: MRI results are not included in this graph, as there were no percent abnormal values for this category.
See this image and copyright information in PMC

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