The influence of age on the gamma-aminobutyric acid concentration of homologue sensorimotor cortices: a 1H-MRS study

Abstract

Background: Aspects of motor performance change with advancing age. Studies using transcranial magnetic stimulation (TMS) observed an altered interhemispheric inhibition in elderly in the primary motor cortex. TMS does not provide information on the neurotransmitter concentration (conc.), the primary inhibitory neurotransmitter being gamma-aminobutyric acid (GABA). Magnetic resonance spectroscopy research mainly revealed a negative correlation between GABA conc. and age. However, research focusing on the primary motor cortex is limited. Objectives: Investigating the effect of aging by comparing the GABA conc. of young and older adults within the same hemisphere. Investigating lateralization by comparing the GABA conc. of different hemispheres within the same age group. Participants: 50 healthy right-handed volunteers, with 25 subjects in the young group and with 25 subjects in the older group. Measurements: Proton magnetic resonance spectroscopy (1H-MRS) at 3.02 ppm is used to measure the GABA conc. of the sensorimotor cortices. The voxels were centered over the two hand knob areas of the left and the right hemispheres. 1H-MRS is executed using a MEGA-PRESS sequence. The outcome measures are tissue corrected for the amount of gray matter, white matter, cerebrospinal fluid and macromolecule contribution. Conclusion: The GABA conc. decline with advancing age in the sensorimotor cortices, but no significant difference in the GABA conc. is observed between the homologue regions of the same age group.