Cortical GABA Concentrations in Insomnia

Disturbances in the amino acid neurotransmitter (AANt), gamma-amino butyric acid (GABA) function are hypothesized to contribute to the neurobiology of Major Depressive Disorder (MDD) and insomnia. The principal objective of this project is to use magnetic resonance spectroscopy (MRS) to provide the first in vivo characterization of cortical GABA levels in individuals with primary insomnia, and to determine whether subjects with MDD, achieving a partial response with selective serotonin reuptake inhibitor treatment but still experiencing significant residual symptoms including insomnia, have altered levels of this neurotransmitter. The investigators are also exploring the correlation between cortical AANt levels and abnormalities in sleep parameters in primary insomnia and as a residual symptom of major depression.