Preserved Neurochemical Balance in the Aging Cerebellum Despite Motor Performance Declines

Introduction: The cerebellum plays a critical role in motor control, coordination, and learning, with its function intricately tied to both structural and functional integrity. Age-related atrophy of cerebellar gray and white matter, particularly in motor-relevant regions, is linked to declines in motor performance. In addition to structural degeneration, neurochemical alterations, such as changes in gamma-aminobutyric acid (GABA) and glutamine (measured in combination with glutamate; Glx) levels, may contribute to age-related motor impairments. Additionally, the role of glutathione (GSH), a key antioxidant, remains underexplored in the cerebellum. Methods: 25 younger and 25 older adults were included in this study. Magnetic resonance spectroscopy (MRS) using the MEGA-PRESS sequence was used to investigate how age affects GABA and GSH levels in the right cerebellar hemisphere. Results: Performance on both the simple and complex task variants of a bimanual tracking task were better in younger compared to older adults (p < 0.0001). However, no significant group differences were observed in cerebellar GABA (p = 0.9018), Glx (p = 0.6748) or GSH levels (p = 0.6416). Discussion: Our findings indicate no significant age-related differences in cerebellar GABA, Glx, or GSH levels, aligning with some studies but differing from others, likely due to the region-specificity of neurometabolic changes. Moreover, age-related cerebellar dysfunction might arise from mechanisms beyond the neurometabolite levels measured in this study, such as changes in norepinephrine modulation or electrophysiological alterations in Purkinje cells. These findings highlight the complexity of age-related cerebellar changes.