Undergraduate Honors Theses

Thesis Defended

Spring 2017

Document Type

Thesis

Type of Thesis

Departmental Honors

Department

Molecular, Cellular, & Developmental Biology

First Advisor

Dr. Scott Vrieze

Second Advisor

Dr. Christy Fillman

Third Advisor

Dr. Matthew McQueen

Abstract

Background

One of the hallmarks of schizophrenia is the presence of psychosis. However, subthreshold psychotic symptoms characterized by attenuated delusions and hallucinations also occur in healthy individuals from the general population. A body of evidence suggests that this phenomenon represents a continuum of schizophrenia, with severe and attenuated symptoms sharing a common genetic etiology. Hallucinations are one subthreshold psychotic symptom in which a clear continuum has been observed. The aim of this study is to assess if subthreshold hallucinatory experiences and schizophrenia share genetic liability.

Method

3,028 participants were administered the Launay-Slade Hallucination Scale (LSHS), which measures a predisposition to hallucinations, through Genes for Good, an online study of health and behavior. A genome-wide association study was conducted for subthreshold hallucinatory experiences. A polygenic risk score was then used to predict subthreshold hallucinatory experiences and assess the existence of a genetic correlation between the two.

Results

No reliable associations with hallucinatory experiences were found that reached genome-wide significance. None of the 124 previously established significantly associated schizophrenia risk variants were found to be significant after correcting for multiple testing. A polygenic risk score based on genetic vulnerability to schizophrenia was unable to successfully predict hallucinatory experiences with scores from the LSHS.

Conclusions

No substantial evidence was found to support the association between genetic liability for subclinical hallucinatory experiences and schizophrenia. The effect between subthreshold hallucinatory experiences and schizophrenia was too small to detect in our sample using a polygenic risk score.