Cortical GABA markers identify a molecular subtype of psychotic and bipolar disorders

• Published in: Psychological medicine Vol. 46; no. 12; pp. 2501 - 2512
• Main Authors: Volk, D. W., Sampson, A. R., Zhang, Y., Edelson, J. R., Lewis, D. A.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.09.2016
• Subjects: Adult; Biomarkers; Biomarkers - metabolism; Bipolar disorder; Bipolar Disorder - metabolism; Calcium; Calcium-binding protein; Clustering; Cortex; Female; GABAergic Neurons - metabolism; Gamma-aminobutyric acid; gamma-Aminobutyric Acid - metabolism; Glutamate Decarboxylase - metabolism; Humans; Individualized; Liability; LIM-Homeodomain Proteins - metabolism; Male; Medical diagnosis; Mental disorders; Middle Aged; Nerve Tissue Proteins - metabolism; Neurons; Original Articles; Parvalbumin; Parvalbumins - metabolism; Phenotype; Phenotypes; Prefrontal cortex; Prefrontal Cortex - metabolism; Psychosis; Psychotic Disorders - metabolism; Schizoaffective disorder; Schizophrenia; Schizophrenia - metabolism; Somatostatin; Somatostatin - metabolism; Transcription Factors - metabolism; γ-Aminobutyric acid; United States > US; Pittsburgh Pennsylvania; schizoaffective; schizophrenia; Inhibitory; postmortem; prefrontal cortex
• DOI: 10.1017/S0033291716001446
• ISSN: 0033-2917; 1469-8978

Deficits in gamma aminobutyric acid (GABA) neuron-related markers, including the GABA-synthesizing enzyme GAD67, the calcium-binding protein parvalbumin, the neuropeptide somatostatin, and the transcription factor Lhx6, are most pronounced in a subset of schizophrenia subjects identified as having a 'low GABA marker' (LGM) molecular phenotype. Furthermore, schizophrenia shares degrees of genetic liability, clinical features and cortical circuitry abnormalities with schizoaffective disorder and bipolar disorder. Therefore, we determined the extent to which a similar LGM molecular phenotype may also exist in subjects with these disorders. Transcript levels for GAD67, parvalbumin, somatostatin, and Lhx6 were quantified using quantitative PCR in prefrontal cortex area 9 of 184 subjects with a diagnosis of schizophrenia (n = 39), schizoaffective disorder (n = 23) or bipolar disorder (n = 35), or with a confirmed absence of any psychiatric diagnoses (n = 87). A blinded clustering approach was employed to determine the presence of a LGM molecular phenotype across all subjects. Approximately 49% of the subjects with schizophrenia, 48% of the subjects with schizoaffective disorder, and 29% of the subjects with bipolar disorder, but only 5% of unaffected subjects, clustered in the cortical LGM molecular phenotype. These findings support the characterization of psychotic and bipolar disorders by cortical molecular phenotype which may help elucidate more pathophysiologically informed and personalized medications.