Brain spectroscopy reveals that N-acetylaspartate is associated to peripheral sensorimotor neuropathy in type 1 diabetes

Aims: Emerging evidence shows, that distal symmetric peripheral neuropathy (DSPN) also involves alterations in the central nervous system. Hence, the aims were to investigate brain metabolites in white matter of adults with diabetes and DSPN, and to compare any cerebral disparities with peripheral nerve characteristics. 

Methods: In type 1 diabetes, brain metabolites of 47 adults with confirmed DSPN were compared with 28 matched healthy controls using proton magnetic resonance spectroscopy (H-MRS) in the parietal region including the sensorimotor fiber tracts. 

Results: Adults with diabetes had 9.3% lower ratio of N-acetylaspartate/creatine (NAA/cre) in comparison to healthy (p < 0.001). Lower NAA/cre was associated with lower sural (p = 0.01) and tibial (p = 0.04) nerve amplitudes, longer diabetes duration (p = 0.03) and higher age (p = 0.03). In addition, NAA/cre was significantly lower in the subgroup with proliferative retinopathy as compared to the subgroup with non-proliferative retinopathy (p = 0.02). 

Conclusions: The association to peripheral nerve dysfunction, indicates concomitant presence of DSPN and central neuropathies, supporting the increasing recognition of diabetic neuropathy being, at least partly, a disease leading to polyneuropathy. Decreased NAA, is a potential promising biomarker of central neuronal dysfunction or loss, and thus may be useful to measure progression of neuropathy in diabetes or other neurodegenerative diseases.