title: Candidate gene networks and blood biomarkers of methamphetamine-associated psychosis: an integrative RNA-sequencing report.
abstract: The clinical presentation, course and treatment of methamphetamine (METH)-associated psychosis (MAP) are similar to that observed in schizophrenia (SCZ) and subsequently MAP has been hypothesized as a pharmacological and environmental model of SCZ. However, several challenges currently exist in diagnosing MAP accurately at the molecular and neurocognitive level before the MAP model can contribute to the discovery of SCZ biomarkers. We directly assessed subcortical brain structural volumes and clinical parameters of MAP within the framework of an integrative genome-wide RNA-Seq blood transcriptome analysis of subjects diagnosed with MAP (N=10), METH dependency without psychosis (MA; N=10) and healthy controls (N=10). First, we identified discrete groups of co-expressed genes (that is, modules) and tested them for functional annotation and phenotypic relationships to brain structure volumes, life events and psychometric measurements. We discovered one MAP-associated module involved in ubiquitin-mediated proteolysis downregulation, enriched with 61 genes previously found implicated in psychosis and SCZ across independent blood and post-mortem brain studies using convergent functional genomic (CFG) evidence. This module demonstrated significant relationships with brain structure volumes including the anterior corpus callosum (CC) and the nucleus accumbens. Furthermore, a second MAP and psychoticism-associated module involved in circadian clock upregulation was also enriched with 39 CFG genes, further associated with the CC. Subsequently, a machine-learning analysis of differentially expressed genes identified single blood-based biomarkers able to differentiate controls from methamphetamine dependents with 87% accuracy and MAP from MA subjects with 95% accuracy. CFG evidence validated a significant proportion of these putative MAP biomarkers in independent studies including CLN3, FBP1, TBC1D2 and ZNF821 (RNA degradation), ELK3 and SINA3 (circadian clock) and PIGF and UHMK1 (ubiquitin-mediated proteolysis). Finally, focusing analysis on brain structure volumes revealed significantly lower bilateral hippocampal volumes in MAP subjects. Overall, these results suggest similar molecular and neurocognitive mechanisms underlying the pathophysiology of psychosis and SCZ regardless of substance abuse and provide preliminary evidence supporting the MAP paradigm as an exemplar for SCZ biomarker discovery.
authors.affiliation: Department of Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, UK.
authors.forename: M S
authors.initials: MS
authors.lastname: Breen
authors.affiliation: Department of Psychiatry and MRC Unit on Anxiety and Stress Disorders, Groote Schuur Hospital (J-2), University of Cape Town, Cape Town, South Africa.
authors.forename: A
authors.initials: A
authors.lastname: Uhlmann
authors.affiliation: Department of Molecular and Cellular Biology, University of Cape Town, Cape Town, South Africa.
authors.forename: C M
authors.initials: CM
authors.lastname: Nday
authors.affiliation: Psychiatric Genetic Epidemiology and Neurobiology Laboratory, Departments of Psychiatry and Behavioral Sciences and Neuroscience and Physiology, Medical Genetics Research Center, SUNY Upstate Medical University, Syracuse, NY, USA.
authors.forename: S J
authors.initials: SJ
authors.lastname: Glatt
authors.affiliation: The Estonian Genome Center, University of Tartu, Tartu, Estonia.
authors.forename: M
authors.initials: M
authors.lastname: Mitt
authors.affiliation: The Estonian Genome Center, University of Tartu, Tartu, Estonia.
authors.forename: A
authors.initials: A
authors.lastname: Metsalpu
authors.affiliation: Department of Psychiatry and MRC Unit on Anxiety and Stress Disorders, Groote Schuur Hospital (J-2), University of Cape Town, Cape Town, South Africa.
authors.forename: D J
authors.initials: DJ
authors.lastname: Stein
authors.affiliation: Department of Molecular and Cellular Biology, University of Cape Town, Cape Town, South Africa.
authors.forename: N
authors.initials: N
authors.lastname: Illing
mesh_terms: D000328:Adult; D019969:Amphetamine-Related Disorders / Q000097:blood* / Q000150:complications / Q000503:physiopathology; D015415:Biomarkers / Q000097:blood; D001921:Brain / Q000503:physiopathology; D005260:Female; D053263:Gene Regulatory Networks / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008694:Methamphetamine / Q000097:blood*; D011605:Psychoses, Substance-Induced / Q000097:blood* / Q000209:etiology / Q000503:physiopathology; D017423:Sequence Analysis, RNA / Q000706:statistics & numerical data*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D008694:Methamphetamine