Effects of age and tissue composition on GABA levels measured with magnetic resonance spectroscopy in the prefrontal cortex in healthy volunteers.

Monday, September 22, 2014 — Poster Session I
12:00 p.m. – 2:00 p.m.	FAES Academic Center	NIMH	NEURO-20

* FARE Award Winner

Authors

• CT Meyer
• S Kuo
• JW van der Veen
• AS Barnett
• DR Weinberger
• KF Berman
• S Marenco

Abstract

184 healthy volunteers (54.3%F, mean age 30.6+9.2SD) were scanned with Magnetic Resonance spectroscopy aimed at measuring GABA levels (press-based J-editing sequence, 3T scanner, 18 cc voxel on dorsal anterior cingulate cortex). GABA levels were expressed as ratios to creatine or water. Sex, race, age and gray matter and CSF composition of the voxel were used as independent variables in backward stepwise regression models. GABA/Cre was associated with age (p = 0.0063) and %gray matter/tissue (GM/tissue) content (p=0.00127). Similar associations were found for GABA/water (p = 0.00090, and p=0.03207, respectively). The interaction of age and GM/tissue was also significant for both (p = 0.00194, 0.00035). For the GABA/water measure, gender (p = 0.02413), %CSF (p = 0.01405) and the interaction of age and CSF (p = 0.04893) were significant. Models that did not include the age-by-GM/tissue interaction showed a negative association between age and GABA levels. Our findings demonstrate that it is critical to account for the interaction of GM/tissue with age in interpreting GABA changes over the lifespan. In order to confirm that the model that best fits the data requires the age*GM/tissue interaction, we plan to replicate the results in two randomly selected subsets of participants.

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